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  • Visual Studio 2010 Released

    - by Latest Microsoft Blogs
    It's a big day at Microsoft today as Visual Studio 2010 officially releases. There's a lot going on with this release and I thought I'd do a big rollup post with lots of details and context to help you find your way to the information and Read More......(read more)

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  • Filtering data in LINQ with the help of where clause

    - by vik20000in
     LINQ has bought with itself a super power of querying Objects, Database, XML, SharePoint and nearly any other data structure. The power of LINQ lies in the fact that it is managed code that lets you write SQL type code to fetch data.  Whenever working with data we always need a way to filter out the data based on different condition. In this post we will look at some of the different ways in which we can filter data in LINQ with the help of where clause. Simple Filter for an array. Let’s say we have an array of number and we want to filter out data based on some condition. Below is an example int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; var lowNums =                 from num in numbers                 where num < 5                 select num;   Filter based on one of the property in the class. With the help of LINQ we can also filer out data from a list based on value of some property. var soldOutProducts =                 from prod in products                 where prod.UnitsInStock == 0                 select prod; Filter based on Multiple of the property in the class. var expensiveInStockProducts =         from prod in products         where prod.UnitsInStock > 0 && prod.UnitPrice > 3.00M         select prod; Filter based on the index of the Item in the list.In the below example we can see that we are able to filter data based on the index of the item in the list. string[] digits = { "zero", "one", "two", "three", "four", "five", "six"}; var shortDigits = digits.Where((digit, index) => digit.Length < index); There are many other way in which we can filter out data in LINQ. In the above post I have tried and shown few ways using the LINQ. Vikram

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  • Code refactoring with Visual Studio 2010 Part-1

    - by Jalpesh P. Vadgama
    Visual studio 2010 is a Great IDE(Integrated Development Environment) and we all are using it in day by day for our coding purpose. There are many great features provided by Visual Studio 2010 and Today I am going to show one of great feature called for code refactoring. This feature is one of the most unappreciated features of Visual Studio 2010 as lots of people still not using that and doing stuff manfully. So to explain feature let’s create a simple console application which will print first name and last name like following. And following is code for that. using System; namespace CodeRefractoring { class Program { static void Main(string[] args) { string firstName = "Jalpesh"; string lastName = "Vadgama"; Console.WriteLine(string.Format("FirstName:{0}",firstName)); Console.WriteLine(string.Format("LastName:{0}", lastName)); Console.ReadLine(); } } } So as you can see this is a very basic console application and let’s run it to see output. So now lets explore our first feature called extract method in visual studio you can also do that via refractor menu like following. Just select the code for which you want to extract method and then click refractor menu and then click extract method. Now I am selecting three lines of code and clicking on refactor –> Extract Method just like following. Once you click menu a dialog box will appear like following. As you can I have highlighted two thing first is Method Name where I put Print as Method Name and another one Preview method signature where its smart enough to extract parameter also as We have just selected three lines with  console.writeline.  One you click ok it will extract the method and you code will be like this. using System; namespace CodeRefractoring { class Program { static void Main(string[] args) { string firstName = "Jalpesh"; string lastName = "Vadgama"; Print(firstName, lastName); } private static void Print(string firstName, string lastName) { Console.WriteLine(string.Format("FirstName:{0}", firstName)); Console.WriteLine(string.Format("LastName:{0}", lastName)); Console.ReadLine(); } } } So as you can see in above code its has created a static method called Print and also passed parameter for as firstname and lastname. Isn’t that great!!!. It has also created static print method as I am calling it from static void main.  Hope you liked it.. Stay tuned for more..Till that Happy programming.

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  • S#arp Architecture 1.5.2 released

    - by AlecWhittington
    It has been a few weeks since S#arp Architecture 1.5 RTM has been released. While it was a major success a few issues were found that needed to be addressed. These mostly involved the Visual Studio templates. What's new in S#arp Architecture 1.5.2? Merged the SharpArch.* assemblies into a single assembly (SharpArch.dll) Updated both VS 2008 and 2010 templates to reflect the use of the merged assembly Updated SharpArch.build with custom script that allows the merging of the assemblies. Copys new merged...(read more)

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  • S#arp Architecture 1.5.1 released

    - by AlecWhittington
    So far we have had some great success with the 1.5 release of S#arp Architecture, but there were a few issues that made it into the release that needed to be corrected. These issues were: Unnecessary assemblies in the root /bin and SolutionItemsContainer folders Nant folder removed from root /bin - this was causing issues with the build scripts that come with the project if the user did not have Nant installed and available via a path variable VS 2010 template - the CrudScaffoldingForEnterpriseApp...(read more)

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  • Encrypted Hidden Redux : Let's Get Salty

    - by HeartattacK
    In this article, Ashic Mahtab shows an elegant, reusable and unobtrusive way in which to persist sensitive data to the browser in hidden inputs and restoring them on postback without needing to change any code in controllers or actions. The approach is an improvement of his previous article and incorporates a per session salt during encryption. Note: Cross posted from Heartysoft.com. Permalink

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  • Is there any real benefit to using ASP.Net Authentication with ASP.Net MVC?

    - by alchemical
    I've been researching this intensely for the past few days. We're developing an ASP.Net MVC site that needs to support 100,000+ users. We'd like to keep it fast, scalable, and simple. We have our own SQL database tables for user and user_role, etc. We are not using server controls. Given that there are no server controls, and a custom membershipProvider would need to be created, where is there any benefit left to use ASP.Net Auth/Membership? The other alternative would seem to be to create custom code to drop a UniqueID CustomerID in a cookie and authenticate with that. Or, if we're paranoid about sniffers, we could encrypt the cookie as well. Is there any real benefit in this scenario (MVC and customer data is in our own tables) to using the ASP.Net auth/membership framework, or is the fully custom solution a viable route?

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  • How to refresh DataGrid and DropDown on main page after hiding modal popup

    - by James
    Hi, I am adding records to a database from a modal popup. After hiding the modal popup, the page has not been refreshed even though I have Rebound the controls. I have reviewed a few postings on the web about this but the solution still evades me. I have attached my code after removing some of the extra detail... It seems I need to cause a postback but I don't know what needs to be changed. Some posts have talked about the extender being misplaced. Anyway, thank you James <asp:Content ID="Content1" ContentPlaceHolderID="Head" Runat="Server"> <div class="divBorder"> <asp:DataGrid id="dgrSessionFolders" runat="server" BorderWidth="2px" BorderStyle="Solid" BorderColor="#C0C0FF" Font-Names="Arial" Font-Bold="True" Font-Size="8pt" GridLines="Horizontal" AutoGenerateColumns="False" PageSize="9999" AllowPaging="False" OnItemCommand="dgrSessionFolders_Command" OnItemDataBound="CheckSessionFolderStatus" HorizontalAlign="Left" ForeColor="Blue" ShowFooter="True" CellPadding="2" OnSortCommand="dgrSessionFolders_Sort" AllowSorting="True"> </asp:DataGrid> </div> &nbsp;&nbsp;&nbsp; <asp:Label ID="Errormsg" runat="server" ForeColor="#CC0000"></asp:Label> <asp:UpdatePanel ID="UpdatePanel1" runat="server" RenderMode="Inline" ChildrenAsTriggers="false" UpdateMode="Conditional"> <Triggers> <asp:AsyncPostBackTrigger ControlID="btnEditTopic" /> <asp:AsyncPostBackTrigger ControlID="btnAdd" /> <asp:AsyncPostBackTrigger ControlID="btnUpdate" /> <asp:AsyncPostBackTrigger ControlID="btnDelete" /> <asp:AsyncPostBackTrigger ControlID="btnClear" /> <asp:AsyncPostBackTrigger ControlID="btnAddTopic" /> <asp:AsyncPostBackTrigger ControlID="btnUpdateTopic" /> <asp:AsyncPostBackTrigger ControlID="btnDeleteTopic" /> </Triggers> <ContentTemplate> <asp:panel id="pnl" runat="server" HorizontalAlign="Center" Height="48px" Width="100%" > &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <asp:ImageButton ID="btnEditTopic" runat="server" AlternateText="Edit Topic" ImageUrl="~/App_Themes/Common/images/BtnEditTopic.jpg" Height="28px"> </asp:ImageButton> <cc1:ModalPopupExtender ID="btnEditTopic_ModalPopupExtender" runat="server" BackgroundCssClass="modalBackground" DropShadow="true" Enabled="true" PopupControlID="pnlEditTopic" TargetControlID="btnEditTopicHidden" CancelControlID="btnEditTopicClose"> </cc1:ModalPopupExtender> <asp:ImageButton ID="btnAdd" runat="server" AlternateText="Add Folder" ImageUrl="~/App_Themes/Common/images/BtnAddFolder.jpg" Height="28px"> </asp:ImageButton> <asp:ImageButton ID="btnUpdate" runat="server" AlternateText="Update Folder" ImageUrl="~/App_Themes/Common/images/BtnUpdateFolder.jpg" Height="28px"> </asp:ImageButton> <asp:ImageButton ID="btnDelete" runat="server" AlternateText="Delete Folder" ImageUrl="~/App_Themes/Common/images/BtnDeleteFolder.jpg" Height="28px"> </asp:ImageButton> <asp:ImageButton ID="BtnClear" runat="server" AlternateText="Clear Screen Input Fields" ImageUrl="~/App_Themes/Common/images/BtnAddMode.jpg" Height="28px"> </asp:ImageButton> <asp:Button ID="btnEditTopicHidden" runat="server" Enabled="false" Text="" Style="visibility: hidden" /> </asp:panel> <asp:Panel ID="pnlEditTopic" runat="server" CssClass="modalPopupEditTopic" Style="display: none;" > <table cellspacing="0" class="borderTable0" width="100%" style=""> <tr> <td colspan="10" class="Subhdr" align="center" style="width:100%"> <asp:label id="lblTopicScreenHdr" Cssclass="ScreenHdr" runat="server">Topic Maintenance</asp:label> </td> </tr> <tr> <td colspan="6"> <asp:Label ID="TopicPopErrorMsg" runat="server" ForeColor="#CC0000">&nbsp;</asp:Label> </td> </tr> <tr style="height:4px"> <td colspan="6" align="center"> <asp:ImageButton ID="btnAddTopic" runat="server" AlternateText="Add Topic" ImageUrl="~/App_Themes/Common/images/BtnApply.jpg" Height="28px"> </asp:ImageButton> <asp:ImageButton ID="btnUpdateTopic" runat="server" AlternateText="Update Topic" ImageUrl="~/App_Themes/Common/images/BtnApply.jpg" Height="28px"> </asp:ImageButton> <asp:ImageButton ID="btnDeleteTopic" runat="server" AlternateText="Delete Topic" ImageUrl="~/App_Themes/Common/images/BtnDelete.jpg" Height="28px"> </asp:ImageButton> <asp:ImageButton ID="btnEditTopicClose" runat="server" AlternateText="Close Edit Topic Popup" ImageUrl="~/App_Themes/Common/images/BtnCancel.jpg" Height="28px"> </asp:ImageButton> </td> </tr> </table> </asp:Panel> </ContentTemplate> </asp:UpdatePanel> Private Sub btnAddTopic_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddTopic.Click 'Add the Topic table entry AddTopic() 'Display an informational message Errormsg.Text = "The Topic has been successfully added, thank you! " Errormsg.ForeColor = Drawing.Color.Blue 'Rebind the Topic Drop Down and set to added Topic ddlSessionTopic.DataBind() ddlSessionTopic.SelectedValue = drTopic("TOPC_ID") 'Rebind the Session Folders grid RebindGrid() 'Hide the Topic Popup btnEditTopic_ModalPopupExtender.Hide() End Sub Private Sub RebindGrid() cnnSQL = New SqlConnection(strConnection) cmdSQL = New SqlCommand("GetSessionFoldersForGrid", cnnSQL) cmdSQL.CommandType = CommandType.StoredProcedure cmdSQL.Parameters.Clear() cnnSQL.Open() dadSQL = New SqlDataAdapter(cmdSQL) dadSQL.SelectCommand = cmdSQL dadSQL.Fill(dtSessionFolderGrid) cnnSQL.Close() dvSessionFolderGrid = dtSessionFolderGrid.DefaultView dvSessionFolderGrid.Sort = String.Format("{0} {1}{2}", so.Sortfield, so.SortDirection, so.SortSuffix) dgrSessionFolders.DataSource = dvSessionFolderGrid dgrSessionFolders.DataBind() End Sub

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  • Getting browser to make an AJAX call ASAP, while page is still loading

    - by Chris
    I'm looking for tips on how to get the browser to kick off an AJAX call as soon as possible into processing a web page, ideally before the page is fully downloaded. Here's my approximate motivation: I have a web page that takes, say, 5 seconds to load. It calls a web service that takes, say, 10 seconds to load. If loading the page and calling the web service happened sequentially, the user would have to wait 15 seconds to see all the information. However, if I can get the web service call started before the 5 second page load is complete, then at least some of the work can happened in parallel. Ideally I'd like as much of the work to happen in parallel as possible. My initial theory was that I should place the AJAX-calling javascript as high up as possible in the web page HTML source (being mindful of putting it after the jquery.js include, because I'm making the call using jquery ajax). I'm also being mindful not to wrap the AJAX call in a jquery ready event handler. (I mention this because ready events are popular in a lot of jquery example code.) However, the AJAX call still doesn't seem to get kicked off as early as I'm hoping (at least as judged by the Google Chrome "Timeline" feature), so I'm wondering what other considerations apply. One thing that might potentially be detrimental is that the AJAX call is back to the same web server that's serving the original web page, so I might be in danger of hitting a browser limit on the # of HTTP connections back to that one machine? (The HTML page loads a number of images, css files, etc..)

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  • VS 2010 SP1 and SQL CE

    - by ScottGu
    Last month we released the Beta of VS 2010 Service Pack 1 (SP1).  You can learn more about the VS 2010 SP1 Beta from Jason Zander’s two blog posts about it, and from Scott Hanselman’s blog post that covers some of the new capabilities enabled with it.   You can download and install the VS 2010 SP1 Beta here. Last week I blogged about the new Visual Studio support for IIS Express that we are adding with VS 2010 SP1. In today’s post I’m going to talk about the new VS 2010 SP1 tooling support for SQL CE, and walkthrough some of the cool scenarios it enables.  SQL CE – What is it and why should you care? SQL CE is a free, embedded, database engine that enables easy database storage. No Database Installation Required SQL CE does not require you to run a setup or install a database server in order to use it.  You can simply copy the SQL CE binaries into the \bin directory of your ASP.NET application, and then your web application can use it as a database engine.  No setup or extra security permissions are required for it to run. You do not need to have an administrator account on the machine. Just copy your web application onto any server and it will work. This is true even of medium-trust applications running in a web hosting environment. SQL CE runs in-memory within your ASP.NET application and will start-up when you first access a SQL CE database, and will automatically shutdown when your application is unloaded.  SQL CE databases are stored as files that live within the \App_Data folder of your ASP.NET Applications. Works with Existing Data APIs SQL CE 4 works with existing .NET-based data APIs, and supports a SQL Server compatible query syntax.  This means you can use existing data APIs like ADO.NET, as well as use higher-level ORMs like Entity Framework and NHibernate with SQL CE.  This enables you to use the same data programming skills and data APIs you know today. Supports Development, Testing and Production Scenarios SQL CE can be used for development scenarios, testing scenarios, and light production usage scenarios.  With the SQL CE 4 release we’ve done the engineering work to ensure that SQL CE won’t crash or deadlock when used in a multi-threaded server scenario (like ASP.NET).  This is a big change from previous releases of SQL CE – which were designed for client-only scenarios and which explicitly blocked running in web-server environments.  Starting with SQL CE 4 you can use it in a web-server as well. There are no license restrictions with SQL CE.  It is also totally free. Easy Migration to SQL Server SQL CE is an embedded database – which makes it ideal for development, testing, and light-usage scenarios.  For high-volume sites and applications you’ll probably want to migrate your database to use SQL Server Express (which is free), SQL Server or SQL Azure.  These servers enable much better scalability, more development features (including features like Stored Procedures – which aren’t supported with SQL CE), as well as more advanced data management capabilities. We’ll ship migration tools that enable you to optionally take SQL CE databases and easily upgrade them to use SQL Server Express, SQL Server, or SQL Azure.  You will not need to change your code when upgrading a SQL CE database to SQL Server or SQL Azure.  Our goal is to enable you to be able to simply change the database connection string in your web.config file and have your application just work. New Tooling Support for SQL CE in VS 2010 SP1 VS 2010 SP1 includes much improved tooling support for SQL CE, and adds support for using SQL CE within ASP.NET projects for the first time.  With VS 2010 SP1 you can now: Create new SQL CE Databases Edit and Modify SQL CE Database Schema and Indexes Populate SQL CE Databases within Data Use the Entity Framework (EF) designer to create model layers against SQL CE databases Use EF Code First to define model layers in code, then create a SQL CE database from them, and optionally edit the DB with VS Deploy SQL CE databases to remote servers using Web Deploy and optionally convert them to full SQL Server databases You can take advantage of all of the above features from within both ASP.NET Web Forms and ASP.NET MVC based projects. Download You can enable SQL CE tooling support within VS 2010 by first installing VS 2010 SP1 (beta). Once SP1 is installed, you’ll also then need to install the SQL CE Tools for Visual Studio download.  This is a separate download that enables the SQL CE tooling support for VS 2010 SP1. Walkthrough of Two Scenarios In this blog post I’m going to walkthrough how you can take advantage of SQL CE and VS 2010 SP1 using both an ASP.NET Web Forms and an ASP.NET MVC based application. Specifically, we’ll walkthrough: How to create a SQL CE database using VS 2010 SP1, then use the EF4 visual designers in Visual Studio to construct a model layer from it, and then display and edit the data using an ASP.NET GridView control. How to use an EF Code First approach to define a model layer using POCO classes and then have EF Code-First “auto-create” a SQL CE database for us based on our model classes.  We’ll then look at how we can use the new VS 2010 SP1 support for SQL CE to inspect the database that was created, populate it with data, and later make schema changes to it.  We’ll do all this within the context of an ASP.NET MVC based application. You can follow the two walkthroughs below on your own machine by installing VS 2010 SP1 (beta) and then installing the SQL CE Tools for Visual Studio download (which is a separate download that enables SQL CE tooling support for VS 2010 SP1). Walkthrough 1: Create a SQL CE Database, Create EF Model Classes, Edit the Data with a GridView This first walkthrough will demonstrate how to create and define a SQL CE database within an ASP.NET Web Form application.  We’ll then build an EF model layer for it and use that model layer to enable data editing scenarios with an <asp:GridView> control. Step 1: Create a new ASP.NET Web Forms Project We’ll begin by using the File->New Project menu command within Visual Studio to create a new ASP.NET Web Forms project.  We’ll use the “ASP.NET Web Application” project template option so that it has a default UI skin implemented: Step 2: Create a SQL CE Database Right click on the “App_Data” folder within the created project and choose the “Add->New Item” menu command: This will bring up the “Add Item” dialog box.  Select the “SQL Server Compact 4.0 Local Database” item (new in VS 2010 SP1) and name the database file to create “Store.sdf”: Note that SQL CE database files have a .sdf filename extension. Place them within the /App_Data folder of your ASP.NET application to enable easy deployment. When we clicked the “Add” button above a Store.sdf file was added to our project: Step 3: Adding a “Products” Table Double-clicking the “Store.sdf” database file will open it up within the Server Explorer tab.  Since it is a new database there are no tables within it: Right click on the “Tables” icon and choose the “Create Table” menu command to create a new database table.  We’ll name the new table “Products” and add 4 columns to it.  We’ll mark the first column as a primary key (and make it an identify column so that its value will automatically increment with each new row): When we click “ok” our new Products table will be created in the SQL CE database. Step 4: Populate with Data Once our Products table is created it will show up within the Server Explorer.  We can right-click it and choose the “Show Table Data” menu command to edit its data: Let’s add a few sample rows of data to it: Step 5: Create an EF Model Layer We have a SQL CE database with some data in it – let’s now create an EF Model Layer that will provide a way for us to easily query and update data within it. Let’s right-click on our project and choose the “Add->New Item” menu command.  This will bring up the “Add New Item” dialog – select the “ADO.NET Entity Data Model” item within it and name it “Store.edmx” This will add a new Store.edmx item to our solution explorer and launch a wizard that allows us to quickly create an EF model: Select the “Generate From Database” option above and click next.  Choose to use the Store.sdf SQL CE database we just created and then click next again.  The wizard will then ask you what database objects you want to import into your model.  Let’s choose to import the “Products” table we created earlier: When we click the “Finish” button Visual Studio will open up the EF designer.  It will have a Product entity already on it that maps to the “Products” table within our SQL CE database: The VS 2010 SP1 EF designer works exactly the same with SQL CE as it does already with SQL Server and SQL Express.  The Product entity above will be persisted as a class (called “Product”) that we can programmatically work against within our ASP.NET application. Step 6: Compile the Project Before using your model layer you’ll need to build your project.  Do a Ctrl+Shift+B to compile the project, or use the Build->Build Solution menu command. Step 7: Create a Page that Uses our EF Model Layer Let’s now create a simple ASP.NET Web Form that contains a GridView control that we can use to display and edit the our Products data (via the EF Model Layer we just created). Right-click on the project and choose the Add->New Item command.  Select the “Web Form from Master Page” item template, and name the page you create “Products.aspx”.  Base the master page on the “Site.Master” template that is in the root of the project. Add an <h2>Products</h2> heading the new Page, and add an <asp:gridview> control within it: Then click the “Design” tab to switch into design-view. Select the GridView control, and then click the top-right corner to display the GridView’s “Smart Tasks” UI: Choose the “New data source…” drop down option above.  This will bring up the below dialog which allows you to pick your Data Source type: Select the “Entity” data source option – which will allow us to easily connect our GridView to the EF model layer we created earlier.  This will bring up another dialog that allows us to pick our model layer: Select the “StoreEntities” option in the dropdown – which is the EF model layer we created earlier.  Then click next – which will allow us to pick which entity within it we want to bind to: Select the “Products” entity in the above dialog – which indicates that we want to bind against the “Product” entity class we defined earlier.  Then click the “Enable automatic updates” checkbox to ensure that we can both query and update Products.  When you click “Finish” VS will wire-up an <asp:EntityDataSource> to your <asp:GridView> control: The last two steps we’ll do will be to click the “Enable Editing” checkbox on the Grid (which will cause the Grid to display an “Edit” link on each row) and (optionally) use the Auto Format dialog to pick a UI template for the Grid. Step 8: Run the Application Let’s now run our application and browse to the /Products.aspx page that contains our GridView.  When we do so we’ll see a Grid UI of the Products within our SQL CE database. Clicking the “Edit” link for any of the rows will allow us to edit their values: When we click “Update” the GridView will post back the values, persist them through our EF Model Layer, and ultimately save them within our SQL CE database. Learn More about using EF with ASP.NET Web Forms Read this tutorial series on the http://asp.net site to learn more about how to use EF with ASP.NET Web Forms.  The tutorial series uses SQL Express as the database – but the nice thing is that all of the same steps/concepts can also now also be done with SQL CE.   Walkthrough 2: Using EF Code-First with SQL CE and ASP.NET MVC 3 We used a database-first approach with the sample above – where we first created the database, and then used the EF designer to create model classes from the database.  In addition to supporting a designer-based development workflow, EF also enables a more code-centric option which we call “code first development”.  Code-First Development enables a pretty sweet development workflow.  It enables you to: Define your model objects by simply writing “plain old classes” with no base classes or visual designer required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping Optionally auto-create a database based on the model classes you define – allowing you to start from code first I’ve done several blog posts about EF Code First in the past – I really think it is great.  The good news is that it also works very well with SQL CE. The combination of SQL CE, EF Code First, and the new VS tooling support for SQL CE, enables a pretty nice workflow.  Below is a simple example of how you can use them to build a simple ASP.NET MVC 3 application. Step 1: Create a new ASP.NET MVC 3 Project We’ll begin by using the File->New Project menu command within Visual Studio to create a new ASP.NET MVC 3 project.  We’ll use the “Internet Project” template so that it has a default UI skin implemented: Step 2: Use NuGet to Install EFCodeFirst Next we’ll use the NuGet package manager (automatically installed by ASP.NET MVC 3) to add the EFCodeFirst library to our project.  We’ll use the Package Manager command shell to do this.  Bring up the package manager console within Visual Studio by selecting the View->Other Windows->Package Manager Console menu command.  Then type: install-package EFCodeFirst within the package manager console to download the EFCodeFirst library and have it be added to our project: When we enter the above command, the EFCodeFirst library will be downloaded and added to our application: Step 3: Build Some Model Classes Using a “code first” based development workflow, we will create our model classes first (even before we have a database).  We create these model classes by writing code. For this sample, we will right click on the “Models” folder of our project and add the below three classes to our project: The “Dinner” and “RSVP” model classes above are “plain old CLR objects” (aka POCO).  They do not need to derive from any base classes or implement any interfaces, and the properties they expose are standard .NET data-types.  No data persistence attributes or data code has been added to them.   The “NerdDinners” class derives from the DbContext class (which is supplied by EFCodeFirst) and handles the retrieval/persistence of our Dinner and RSVP instances from a database. Step 4: Listing Dinners We’ve written all of the code necessary to implement our model layer for this simple project.  Let’s now expose and implement the URL: /Dinners/Upcoming within our project.  We’ll use it to list upcoming dinners that happen in the future. We’ll do this by right-clicking on our “Controllers” folder and select the “Add->Controller” menu command.  We’ll name the Controller we want to create “DinnersController”.  We’ll then implement an “Upcoming” action method within it that lists upcoming dinners using our model layer above.  We will use a LINQ query to retrieve the data and pass it to a View to render with the code below: We’ll then right-click within our Upcoming method and choose the “Add-View” menu command to create an “Upcoming” view template that displays our dinners.  We’ll use the “empty” template option within the “Add View” dialog and write the below view template using Razor: Step 4: Configure our Project to use a SQL CE Database We have finished writing all of our code – our last step will be to configure a database connection-string to use. We will point our NerdDinners model class to a SQL CE database by adding the below <connectionString> to the web.config file at the top of our project: EF Code First uses a default convention where context classes will look for a connection-string that matches the DbContext class name.  Because we created a “NerdDinners” class earlier, we’ve also named our connectionstring “NerdDinners”.  Above we are configuring our connection-string to use SQL CE as the database, and telling it that our SQL CE database file will live within the \App_Data directory of our ASP.NET project. Step 5: Running our Application Now that we’ve built our application, let’s run it! We’ll browse to the /Dinners/Upcoming URL – doing so will display an empty list of upcoming dinners: You might ask – but where did it query to get the dinners from? We didn’t explicitly create a database?!? One of the cool features that EF Code-First supports is the ability to automatically create a database (based on the schema of our model classes) when the database we point it at doesn’t exist.  Above we configured  EF Code-First to point at a SQL CE database in the \App_Data\ directory of our project.  When we ran our application, EF Code-First saw that the SQL CE database didn’t exist and automatically created it for us. Step 6: Using VS 2010 SP1 to Explore our newly created SQL CE Database Click the “Show all Files” icon within the Solution Explorer and you’ll see the “NerdDinners.sdf” SQL CE database file that was automatically created for us by EF code-first within the \App_Data\ folder: We can optionally right-click on the file and “Include in Project" to add it to our solution: We can also double-click the file (regardless of whether it is added to the project) and VS 2010 SP1 will open it as a database we can edit within the “Server Explorer” tab of the IDE. Below is the view we get when we double-click our NerdDinners.sdf SQL CE file.  We can drill in to see the schema of the Dinners and RSVPs tables in the tree explorer.  Notice how two tables - Dinners and RSVPs – were automatically created for us within our SQL CE database.  This was done by EF Code First when we accessed the NerdDinners class by running our application above: We can right-click on a Table and use the “Show Table Data” command to enter some upcoming dinners in our database: We’ll use the built-in editor that VS 2010 SP1 supports to populate our table data below: And now when we hit “refresh” on the /Dinners/Upcoming URL within our browser we’ll see some upcoming dinners show up: Step 7: Changing our Model and Database Schema Let’s now modify the schema of our model layer and database, and walkthrough one way that the new VS 2010 SP1 Tooling support for SQL CE can make this easier.  With EF Code-First you typically start making database changes by modifying the model classes.  For example, let’s add an additional string property called “UrlLink” to our “Dinner” class.  We’ll use this to point to a link for more information about the event: Now when we re-run our project, and visit the /Dinners/Upcoming URL we’ll see an error thrown: We are seeing this error because EF Code-First automatically created our database, and by default when it does this it adds a table that helps tracks whether the schema of our database is in sync with our model classes.  EF Code-First helpfully throws an error when they become out of sync – making it easier to track down issues at development time that you might otherwise only find (via obscure errors) at runtime.  Note that if you do not want this feature you can turn it off by changing the default conventions of your DbContext class (in this case our NerdDinners class) to not track the schema version. Our model classes and database schema are out of sync in the above example – so how do we fix this?  There are two approaches you can use today: Delete the database and have EF Code First automatically re-create the database based on the new model class schema (losing the data within the existing DB) Modify the schema of the existing database to make it in sync with the model classes (keeping/migrating the data within the existing DB) There are a couple of ways you can do the second approach above.  Below I’m going to show how you can take advantage of the new VS 2010 SP1 Tooling support for SQL CE to use a database schema tool to modify our database structure.  We are also going to be supporting a “migrations” feature with EF in the future that will allow you to automate/script database schema migrations programmatically. Step 8: Modify our SQL CE Database Schema using VS 2010 SP1 The new SQL CE Tooling support within VS 2010 SP1 makes it easy to modify the schema of our existing SQL CE database.  To do this we’ll right-click on our “Dinners” table and choose the “Edit Table Schema” command: This will bring up the below “Edit Table” dialog.  We can rename, change or delete any of the existing columns in our table, or click at the bottom of the column listing and type to add a new column.  Below I’ve added a new “UrlLink” column of type “nvarchar” (since our property is a string): When we click ok our database will be updated to have the new column and our schema will now match our model classes. Because we are manually modifying our database schema, there is one additional step we need to take to let EF Code-First know that the database schema is in sync with our model classes.  As i mentioned earlier, when a database is automatically created by EF Code-First it adds a “EdmMetadata” table to the database to track schema versions (and hash our model classes against them to detect mismatches between our model classes and the database schema): Since we are manually updating and maintaining our database schema, we don’t need this table – and can just delete it: This will leave us with just the two tables that correspond to our model classes: And now when we re-run our /Dinners/Upcoming URL it will display the dinners correctly: One last touch we could do would be to update our view to check for the new UrlLink property and render a <a> link to it if an event has one: And now when we refresh our /Dinners/Upcoming we will see hyperlinks for the events that have a UrlLink stored in the database: Summary SQL CE provides a free, embedded, database engine that you can use to easily enable database storage.  With SQL CE 4 you can now take advantage of it within ASP.NET projects and applications (both Web Forms and MVC). VS 2010 SP1 provides tooling support that enables you to easily create, edit and modify SQL CE databases – as well as use the standard EF designer against them.  This allows you to re-use your existing skills and data knowledge while taking advantage of an embedded database option.  This is useful both for small applications (where you don’t need the scalability of a full SQL Server), as well as for development and testing scenarios – where you want to be able to rapidly develop/test your application without having a full database instance.  SQL CE makes it easy to later migrate your data to a full SQL Server or SQL Azure instance if you want to – without having to change any code in your application.  All we would need to change in the above two scenarios is the <connectionString> value within the web.config file in order to have our code run against a full SQL Server.  This provides the flexibility to scale up your application starting from a small embedded database solution as needed. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Localization in ASP.NET MVC 2 using ModelMetadata

    - by rajbk
    This post uses an MVC 2 RTM application inside VS 2010 that is targeting the .NET Framework 4. .NET 4 DataAnnotations comes with a new Display attribute that has several properties including specifying the value that is used for display in the UI and a ResourceType. Unfortunately, this attribute is new and is not supported in MVC 2 RTM. The good news is it will be supported and is currently available in the MVC Futures release. The steps to get this working are shown below: Download the MVC futures library   Add a reference to the Microsoft.Web.MVC.AspNet4 dll.   Add a folder in your MVC project where you will store the resx files   Open the resx file and change “Access Modifier” to “Public”. This allows the resources to accessible from other assemblies. Internaly, it changes the “Custom Tool” used to generate the code behind from  ResXFileCodeGenerator to “PublicResXFileCodeGenerator”    Add your localized strings in the resx.   Register the new ModelMetadataProvider protected void Application_Start() { AreaRegistration.RegisterAllAreas();   RegisterRoutes(RouteTable.Routes);   //Add this ModelMetadataProviders.Current = new DataAnnotations4ModelMetadataProvider(); DataAnnotations4ModelValidatorProvider.RegisterProvider(); }   Use the Display attribute in your Model public class Employee { [Display(Name="ID")] public int ID { get; set; }   [Display(ResourceType = typeof(Common), Name="Name")] public string Name { get; set; } } Use the new HTML UI Helpers in your strongly typed view: <%: Html.EditorForModel() %> <%: Html.EditorFor(m => m) %> <%: Html.LabelFor(m => m.Name) %> ..and you are good to go. Adventure is out there!

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  • Where is ScriptManager.IsStartupScriptRegistered method?

    - by Ismail S
    Below is my code if (!Page.ClientScript.IsStartupScriptRegistered(Page.GetType(), scriptKey)) { ScriptManager scriptManager = ScriptManager.GetCurrent(page); if (scriptManager != null && scriptManager.IsInAsyncPostBack) { //if a MS AJAX request, use the Scriptmanager class ScriptManager.RegisterStartupScript(Page, Page.GetType(), scriptKey, script, true); } else { //if a standard postback, use the standard ClientScript method Page.ClientScript.RegisterStartupScript(Page.GetType(), scriptKey, script, true); } } I'm doing as suggested in this answer so that I can register startup script on both times i.e. when there is partial postback and a full postback. The problem is Page.ClientScript.IsStartupScriptRegistered(Page.GetType(), scriptKey) always returns false when it is partial postback. And I couldn't find ScriptManager.IsStartupScriptRegistered method. As a result of this additional script is emitted on all partial/async postbacks. Please note that I'm using script manager of AjaxControlToolkit version 4.1 i.e. ToolkitScriptManager in my masterpage. But I don't thing it has something to do with this. UPDATE <asp:UpdatePanel ID="ContactDetailsUpdatePanel" UpdateMode="Conditional" runat="server"> <Triggers> <asp:AsyncPostBackTrigger ControlID="UpdateContactDetailsButton" EventName="Click" /> </Triggers> <ContentTemplate> <div id="ContactDetailsContent" class="contact_details_content"> <div class="customer_contactdetails_left_pane"> <div class="customer_name_field"> <asp:Label ID="CustomerNameLabel" runat="server" Text="Customer" /> <asp:TextBox ID="CustomerNameValue" runat="server" /> </div> <div class="customer_address_field"> <asp:Label ID="CustomerAddressLabel" runat="server" Text="Address" /> <asp:TextBox ID="CustomerAddressValue" runat="server" /> <asp:TextBox ID="CustomerAddressValue1" runat="server" /> <asp:TextBox ID="CustomerAddressValue2" runat="server" /> <asp:TextBox ID="CustomerAddressValue3" runat="server" /> </div> <div class="customer_postcode_field"> <asp:Label ID="CustomerPostcodeLabel" runat="server" Text="Postcode" /> <asp:TextBox ID="CustomerPostcodeValue" runat="server" /> </div> </div> <div class="customer_contactdetails_right_pane"> <div> <asp:Label ID="CustomerContactLabel" runat="server" Text="Contact" /> <asp:TextBox ID="CustomerContactValue" runat="server" /> </div> <div> <asp:Label ID="CustomerTelephoneLabel" runat="server" Text="Telephone" /> <asp:TextBox ID="CustomerTelephoneValue" runat="server" /> </div> <div> <asp:Label ID="CustomerMobileLabel" runat="server" Text="Mobile" /> <asp:TextBox ID="CustomerMobileValue" runat="server" /> </div> <div> <asp:Label ID="CustomerFaxLabel" runat="server" Text="Fax" /> <asp:TextBox ID="CustomerFaxValue" runat="server" /> </div> <div> <asp:Label ID="CustomerEmailLabel" runat="server" Text="Email" /> <asp:TextBox ID="CustomerEmailValue" runat="server" /> </div> <div> <asp:Label ID="CustomerWebLabel" runat="server" Text="Web" /> <asp:TextBox ID="CustomerWebValue" runat="server" /> </div> </div> </div> <div class="update_button_field"> <asp:Button ID="UpdateContactDetailsButton" runat="server" Text="Update" onclick="UpdateContactDetailsButton_Click" /> </div> </ContentTemplate> </asp:UpdatePanel> Thanks in advance.

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  • Recommend ASP.NET 3.5 SP1 Hosting Providers

    - by tyndall
    Would like to see a list of affordable ASP.NET 3.5 SP1 Hosting providers build up. Along with your review of the service, lacking features, special features, etc... Discount ASP.NET MochaHost At last update MochaHost does not offer SP1  they now offer SP1 CrystalTech Gearhost HostMySite please add more update: Anybody see a better deal for shared hosting ASP.NET than ASP.NETpro From GearHost? I would like to see more SQL storage, but I need keep the multiple domain capabilities. For about the same price.

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  • Is it necessary to create ASP.NET 4.0 SQL session state database, distinct from existing ASP.NET 2.0

    - by Chris W. Rea
    Is the ASP.NET 4.0 SQL session state mechanism backward-compatible with the ASP.NET 2.0 schema for session state, or should/must we create a separate and distinct session state database for our ASP.NET 4.0 apps? I'm leaning towards the latter anyway, but the 2.0 database seems to just work, though I'm wondering if there are any substantive differences between the ASPState database schema / procedures between the 2.0 and 4.0 versions of ASP.NET. Thank you.

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  • Using jQuery to Insert a New Database Record

    - by Stephen Walther
    The goal of this blog entry is to explore the easiest way of inserting a new record into a database using jQuery and .NET. I’m going to explore two approaches: using Generic Handlers and using a WCF service (In a future blog entry I’ll take a look at OData and WCF Data Services). Create the ASP.NET Project I’ll start by creating a new empty ASP.NET application with Visual Studio 2010. Select the menu option File, New Project and select the ASP.NET Empty Web Application project template. Setup the Database and Data Model I’ll use my standard MoviesDB.mdf movies database. This database contains one table named Movies that looks like this: I’ll use the ADO.NET Entity Framework to represent my database data: Select the menu option Project, Add New Item and select the ADO.NET Entity Data Model project item. Name the data model MoviesDB.edmx and click the Add button. In the Choose Model Contents step, select Generate from database and click the Next button. In the Choose Your Data Connection step, leave all of the defaults and click the Next button. In the Choose Your Data Objects step, select the Movies table and click the Finish button. Unfortunately, Visual Studio 2010 cannot spell movie correctly :) You need to click on Movy and change the name of the class to Movie. In the Properties window, change the Entity Set Name to Movies. Using a Generic Handler In this section, we’ll use jQuery with an ASP.NET generic handler to insert a new record into the database. A generic handler is similar to an ASP.NET page, but it does not have any of the overhead. It consists of one method named ProcessRequest(). Select the menu option Project, Add New Item and select the Generic Handler project item. Name your new generic handler InsertMovie.ashx and click the Add button. Modify your handler so it looks like Listing 1: Listing 1 – InsertMovie.ashx using System.Web; namespace WebApplication1 { /// <summary> /// Inserts a new movie into the database /// </summary> public class InsertMovie : IHttpHandler { private MoviesDBEntities _dataContext = new MoviesDBEntities(); public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; // Extract form fields var title = context.Request["title"]; var director = context.Request["director"]; // Create movie to insert var movieToInsert = new Movie { Title = title, Director = director }; // Save new movie to DB _dataContext.AddToMovies(movieToInsert); _dataContext.SaveChanges(); // Return success context.Response.Write("success"); } public bool IsReusable { get { return true; } } } } In Listing 1, the ProcessRequest() method is used to retrieve a title and director from form parameters. Next, a new Movie is created with the form values. Finally, the new movie is saved to the database and the string “success” is returned. Using jQuery with the Generic Handler We can call the InsertMovie.ashx generic handler from jQuery by using the standard jQuery post() method. The following HTML page illustrates how you can retrieve form field values and post the values to the generic handler: Listing 2 – Default.htm <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Add Movie</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input name="title" /> <br /> <label>Director:</label> <input name="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { $.post("InsertMovie.ashx", $("form").serialize(), insertCallback); }); function insertCallback(result) { if (result == "success") { alert("Movie added!"); } else { alert("Could not add movie!"); } } </script> </body> </html>     When you open the page in Listing 2 in a web browser, you get a simple HTML form: Notice that the page in Listing 2 includes the jQuery library. The jQuery library is included with the following SCRIPT tag: <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> The jQuery library is included on the Microsoft Ajax CDN so you can always easily include the jQuery library in your applications. You can learn more about the CDN at this website: http://www.asp.net/ajaxLibrary/cdn.ashx When you click the Add Movie button, the jQuery post() method is called to post the form data to the InsertMovie.ashx generic handler. Notice that the form values are serialized into a URL encoded string by calling the jQuery serialize() method. The serialize() method uses the name attribute of form fields and not the id attribute. Notes on this Approach This is a very low-level approach to interacting with .NET through jQuery – but it is simple and it works! And, you don’t need to use any JavaScript libraries in addition to the jQuery library to use this approach. The signature for the jQuery post() callback method looks like this: callback(data, textStatus, XmlHttpRequest) The second parameter, textStatus, returns the HTTP status code from the server. I tried returning different status codes from the generic handler with an eye towards implementing server validation by returning a status code such as 400 Bad Request when validation fails (see http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html ). I finally figured out that the callback is not invoked when the textStatus has any value other than “success”. Using a WCF Service As an alternative to posting to a generic handler, you can create a WCF service. You create a new WCF service by selecting the menu option Project, Add New Item and selecting the Ajax-enabled WCF Service project item. Name your WCF service InsertMovie.svc and click the Add button. Modify the WCF service so that it looks like Listing 3: Listing 3 – InsertMovie.svc using System.ServiceModel; using System.ServiceModel.Activation; namespace WebApplication1 { [ServiceBehavior(IncludeExceptionDetailInFaults=true)] [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class MovieService { private MoviesDBEntities _dataContext = new MoviesDBEntities(); [OperationContract] public bool Insert(string title, string director) { // Create movie to insert var movieToInsert = new Movie { Title = title, Director = director }; // Save new movie to DB _dataContext.AddToMovies(movieToInsert); _dataContext.SaveChanges(); // Return movie (with primary key) return true; } } }   The WCF service in Listing 3 uses the Entity Framework to insert a record into the Movies database table. The service always returns the value true. Notice that the service in Listing 3 includes the following attribute: [ServiceBehavior(IncludeExceptionDetailInFaults=true)] You need to include this attribute if you want to get detailed error information back to the client. When you are building an application, you should always include this attribute. When you are ready to release your application, you should remove this attribute for security reasons. Using jQuery with the WCF Service Calling a WCF service from jQuery requires a little more work than calling a generic handler from jQuery. Here are some good blog posts on some of the issues with using jQuery with WCF: http://encosia.com/2008/06/05/3-mistakes-to-avoid-when-using-jquery-with-aspnet-ajax/ http://encosia.com/2008/03/27/using-jquery-to-consume-aspnet-json-web-services/ http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx http://www.west-wind.com/Weblog/posts/896411.aspx http://www.west-wind.com/weblog/posts/324917.aspx http://professionalaspnet.com/archive/tags/WCF/default.aspx The primary requirement when calling WCF from jQuery is that the request use JSON: The request must include a content-type:application/json header. Any parameters included with the request must be JSON encoded. Unfortunately, jQuery does not include a method for serializing JSON (Although, oddly, jQuery does include a parseJSON() method for deserializing JSON). Therefore, we need to use an additional library to handle the JSON serialization. The page in Listing 4 illustrates how you can call a WCF service from jQuery. Listing 4 – Default2.aspx <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Add Movie</title> <script src="http://ajax.microsoft.com/ajax/jquery/jquery-1.4.2.js" type="text/javascript"></script> <script src="Scripts/json2.js" type="text/javascript"></script> </head> <body> <form> <label>Title:</label> <input id="title" /> <br /> <label>Director:</label> <input id="director" /> </form> <button id="btnAdd">Add Movie</button> <script type="text/javascript"> $("#btnAdd").click(function () { // Convert the form into an object var data = { title: $("#title").val(), director: $("#director").val() }; // JSONify the data data = JSON.stringify(data); // Post it $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", url: "MovieService.svc/Insert", data: data, dataType: "json", success: insertCallback }); }); function insertCallback(result) { // unwrap result result = result["d"]; if (result === true) { alert("Movie added!"); } else { alert("Could not add movie!"); } } </script> </body> </html> There are several things to notice about Listing 4. First, notice that the page includes both the jQuery library and Douglas Crockford’s JSON2 library: <script src="Scripts/json2.js" type="text/javascript"></script> You need to include the JSON2 library to serialize the form values into JSON. You can download the JSON2 library from the following location: http://www.json.org/js.html When you click the button to submit the form, the form data is converted into a JavaScript object: // Convert the form into an object var data = { title: $("#title").val(), director: $("#director").val() }; Next, the data is serialized into JSON using the JSON2 library: // JSONify the data var data = JSON.stringify(data); Finally, the form data is posted to the WCF service by calling the jQuery ajax() method: // Post it $.ajax({   type: "POST",   contentType: "application/json; charset=utf-8",   url: "MovieService.svc/Insert",   data: data,   dataType: "json",   success: insertCallback }); You can’t use the standard jQuery post() method because you must set the content-type of the request to be application/json. Otherwise, the WCF service will reject the request for security reasons. For details, see the Scott Guthrie blog post: http://weblogs.asp.net/scottgu/archive/2007/04/04/json-hijacking-and-how-asp-net-ajax-1-0-mitigates-these-attacks.aspx The insertCallback() method is called when the WCF service returns a response. This method looks like this: function insertCallback(result) {   // unwrap result   result = result["d"];   if (result === true) {       alert("Movie added!");   } else {     alert("Could not add movie!");   } } When we called the jQuery ajax() method, we set the dataType to JSON. That causes the jQuery ajax() method to deserialize the response from the WCF service from JSON into a JavaScript object automatically. The following value is passed to the insertCallback method: {"d":true} For security reasons, a WCF service always returns a response with a “d” wrapper. The following line of code removes the “d” wrapper: // unwrap result result = result["d"]; To learn more about the “d” wrapper, I recommend that you read the following blog posts: http://encosia.com/2009/02/10/a-breaking-change-between-versions-of-aspnet-ajax/ http://encosia.com/2009/06/29/never-worry-about-asp-net-ajaxs-d-again/ Summary In this blog entry, I explored two methods of inserting a database record using jQuery and .NET. First, we created a generic handler and called the handler from jQuery. This is a very low-level approach. However, it is a simple approach that works. Next, we looked at how you can call a WCF service using jQuery. This approach required a little more work because you need to serialize objects into JSON. We used the JSON2 library to perform the serialization. In the next blog post, I want to explore how you can use jQuery with OData and WCF Data Services.

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  • ASP.NET MVC 3: Razor’s @: and <text> syntax

    - by ScottGu
    This is another in a series of posts I’m doing that cover some of the new ASP.NET MVC 3 features: New @model keyword in Razor (Oct 19th) Layouts with Razor (Oct 22nd) Server-Side Comments with Razor (Nov 12th) Razor’s @: and <text> syntax (today) In today’s post I’m going to discuss two useful syntactical features of the new Razor view-engine – the @: and <text> syntax support. Fluid Coding with Razor ASP.NET MVC 3 ships with a new view-engine option called “Razor” (in addition to the existing .aspx view engine).  You can learn more about Razor, why we are introducing it, and the syntax it supports from my Introducing Razor blog post.  Razor minimizes the number of characters and keystrokes required when writing a view template, and enables a fast, fluid coding workflow. Unlike most template syntaxes, you do not need to interrupt your coding to explicitly denote the start and end of server blocks within your HTML. The Razor parser is smart enough to infer this from your code. This enables a compact and expressive syntax which is clean, fast and fun to type. For example, the Razor snippet below can be used to iterate a list of products: When run, it generates output like:   One of the techniques that Razor uses to implicitly identify when a code block ends is to look for tag/element content to denote the beginning of a content region.  For example, in the code snippet above Razor automatically treated the inner <li></li> block within our foreach loop as an HTML content block because it saw the opening <li> tag sequence and knew that it couldn’t be valid C#.  This particular technique – using tags to identify content blocks within code – is one of the key ingredients that makes Razor so clean and productive with scenarios involving HTML creation. Using @: to explicitly indicate the start of content Not all content container blocks start with a tag element tag, though, and there are scenarios where the Razor parser can’t implicitly detect a content block. Razor addresses this by enabling you to explicitly indicate the beginning of a line of content by using the @: character sequence within a code block.  The @: sequence indicates that the line of content that follows should be treated as a content block: As a more practical example, the below snippet demonstrates how we could output a “(Out of Stock!)” message next to our product name if the product is out of stock: Because I am not wrapping the (Out of Stock!) message in an HTML tag element, Razor can’t implicitly determine that the content within the @if block is the start of a content block.  We are using the @: character sequence to explicitly indicate that this line within our code block should be treated as content. Using Code Nuggets within @: content blocks In addition to outputting static content, you can also have code nuggets embedded within a content block that is initiated using a @: character sequence.  For example, we have two @: sequences in the code snippet below: Notice how within the second @: sequence we are emitting the number of units left within the content block (e.g. - “(Only 3 left!”). We are doing this by embedding a @p.UnitsInStock code nugget within the line of content. Multiple Lines of Content Razor makes it easy to have multiple lines of content wrapped in an HTML element.  For example, below the inner content of our @if container is wrapped in an HTML <p> element – which will cause Razor to treat it as content: For scenarios where the multiple lines of content are not wrapped by an outer HTML element, you can use multiple @: sequences: Alternatively, Razor also allows you to use a <text> element to explicitly identify content: The <text> tag is an element that is treated specially by Razor. It causes Razor to interpret the inner contents of the <text> block as content, and to not render the containing <text> tag element (meaning only the inner contents of the <text> element will be rendered – the tag itself will not).  This makes it convenient when you want to render multi-line content blocks that are not wrapped by an HTML element.  The <text> element can also optionally be used to denote single-lines of content, if you prefer it to the more concise @: sequence: The above code will render the same output as the @: version we looked at earlier.  Razor will automatically omit the <text> wrapping element from the output and just render the content within it.  Summary Razor enables a clean and concise templating syntax that enables a very fluid coding workflow.  Razor’s smart detection of <tag> elements to identify the beginning of content regions is one of the reasons that the Razor approach works so well with HTML generation scenarios, and it enables you to avoid having to explicitly mark the beginning/ending of content regions in about 95% of if/else and foreach scenarios. Razor’s @: and <text> syntax can then be used for scenarios where you want to avoid using an HTML element within a code container block, and need to more explicitly denote a content region. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • How to access HTML elements from server side code in an asp.net website

    - by nikolaosk
    In this post I will demonstrate with a hands on example how HTML elements in an .aspx page can be processed exactly like standard ASP.Net server controls. Basically how to make them accessible from server side code. 1) Launch Visual Studio 2010/2008/2005. (express editions will work fine). Create a new empty website and choose a suitable name for it. Choose VB as the development language. 2) Add a new item in your site, a web form. Leave the default name. 3) Let's say that we want to change the background...(read more)

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  • Are there any advantages to using ASP.Net MVC 3 over Ruby On Rails for existing businesses? [closed]

    - by user786621
    Possible Duplicate: What ASP.NET MVC can do and Ruby on Rails can't? I've been hearing a lot of good press about Ruby On Rails but I'm having a hard time finding much information on the advantages of using ASP.Net MVC 3 over RoR, yet I see many existing businesses migrating over to ASP.Net MVC. Does ASP.Net MVC 3 have any advantages over Ruby On Rails for existing businesses such as possibly tying into old databases better or allowing for more complex business logic? Or is it most likely the case that they are transferring simply because they were already using ASP.Net for Winforms?

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  • A basic T4 template for generating Model Metadata in ASP.NET MVC2

    - by rajbk
    I have been learning about T4 templates recently by looking at the awesome ADO.NET POCO entity generator. By using the POCO entity generator template as a base, I created a T4 template which generates metadata classes for a given Entity Data Model. This speeds coding by reducing the amount of typing required when creating view specific model and its metadata. To use this template, Download the template provided at the bottom. Set two values in the template file. The first one should point to the EDM you wish to generate metadata for. The second is used to suffix the namespace and classes that get generated. string inputFile = @"Northwind.edmx"; string suffix = "AutoMetadata"; Add the template to your MVC 2 Visual Studio 2010 project. Once you add it, a number of classes will get added to your project based on the number of entities you have.    One of these classes is shown below. Note that the DisplayName, Required and StringLength attributes have been added by the t4 template. //------------------------------------------------------------------------------ // <auto-generated> // This code was generated from a template. // // Changes to this file may cause incorrect behavior and will be lost if // the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------   using System; using System.ComponentModel; using System.ComponentModel.DataAnnotations;   namespace NorthwindSales.ModelsAutoMetadata { public partial class CustomerAutoMetadata { [DisplayName("Customer ID")] [Required] [StringLength(5)] public string CustomerID { get; set; } [DisplayName("Company Name")] [Required] [StringLength(40)] public string CompanyName { get; set; } [DisplayName("Contact Name")] [StringLength(30)] public string ContactName { get; set; } [DisplayName("Contact Title")] [StringLength(30)] public string ContactTitle { get; set; } [DisplayName("Address")] [StringLength(60)] public string Address { get; set; } [DisplayName("City")] [StringLength(15)] public string City { get; set; } [DisplayName("Region")] [StringLength(15)] public string Region { get; set; } [DisplayName("Postal Code")] [StringLength(10)] public string PostalCode { get; set; } [DisplayName("Country")] [StringLength(15)] public string Country { get; set; } [DisplayName("Phone")] [StringLength(24)] public string Phone { get; set; } [DisplayName("Fax")] [StringLength(24)] public string Fax { get; set; } } } The gen’d class can be used from your project by creating a partial class with the entity name and setting the MetadataType attribute.namespace MyProject.Models{ [MetadataType(typeof(CustomerAutoMetadata))] public partial class Customer { }} You can also copy the code in the metadata class generated and create your own ViewModel class. Note that the template is super basic  and does not take into account complex properties. I have tested it with the Northwind database. This is a work in progress. Feel free to modify the template to suite your requirements. Standard disclaimer follows: Use At Your Own Risk, Works on my machine running VS 2010 RTM/ASP.NET MVC 2 AutoMetaData.zip Mr. Incredible: Of course I have a secret identity. I don't know a single superhero who doesn't. Who wants the pressure of being super all the time?

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  • AJAX CascadingDropDown ViewState Problem

    - by Steven
    Question: How do I maintain both the contents (from queries) and selected value of both dropdowns after postback? Source Code: Download my source code from this link (link now works). Just add a reference to your AjaxControlToolkit User Action: Select a value from each dropdown. Click Submit. After Postback: StatesDrop: (Selected value), CitiesDrop "Select a City" Before and after: I believe that when the first dropdown gets its selected value, the second dropdown refreshes and therefore loses its selected value. C# answers also welcome. Default.aspx Active States<br /><asp:DropDownList ID="StatesDrop" runat="server" /><br /> Active Cities<br /><asp:DropDownList ID="CitiesDrop" runat="server" /><br /> <ajax:CascadingDropDown ID="StatesCasc" TargetControlID="StatesDrop" ServicePath="WebService1.asmx" ServiceMethod="GetActiveStates" Category="States" runat="server" PromptText="Select a State" PromptValue="?" /> <ajax:CascadingDropDown ID="CitiesCasc" TargetControlID="CitiesDrop" ServicePath="WebService1.asmx" ServiceMethod="GetActiveCities" Category="Cities" runat="server" ParentControlID="StatesDrop" PromptText="Select a City" PromptValue="?" /> WebService1.asmx.vb Imports System.Web.Services Imports System.Web.Services.Protocols Imports System.ComponentModel Imports System.Web.Script.Services Imports AjaxControlToolkit <System.Web.Script.Services.ScriptService()> _ <System.Web.Services.WebService(Namespace:="http://tempuri.org/")> _ <System.Web.Services.WebServiceBinding _ (ConformsTo:=WsiProfiles.BasicProfile1_1)> _ <ToolboxItem(False)> _ Public Class WebService1: Inherits System.Web.Services.WebService <WebMethod()> _ Public Function GetActiveStates (ByVal knownCategoryValues As String, _ ByVal category As String) As CascadingDropDownNameValue() Dim values As New List(Of CascadingDropDownNameValue)() 'Fill values array' Return values.ToArray() End Function <WebMethod()> _ Public Function GetActiveCities (ByVal knownCategoryValues As String, _ ByVal category As String) As CascadingDropDownNameValue() Dim values As New List(Of CascadingDropDownNameValue)() Dim kv As StringDictionary = _ CascadingDropDown.ParseKnownCategoryValuesString(knownCategoryValues) Dim SelState As String = "" If kv.ContainsKey("State") Then SelState = kv("State") 'Fill values array' Return values.ToArray() End Function End Class Default.aspx.vb Imports System.Web.Services Imports System.Web.Script.Services Imports AjaxControlToolkit Partial Public Class _Default Inherits System.Web.UI.Page Protected Sub Submit_Click(ByVal sender As Object, _ ByVal e As EventArgs) Handles SubmitBtn.Click ResultsGrid.DataBind() End Sub End Class

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  • Securing an ASP.NET MVC 2 Application

    - by rajbk
    This post attempts to look at some of the methods that can be used to secure an ASP.NET MVC 2 Application called Northwind Traders Human Resources.  The sample code for the project is attached at the bottom of this post. We are going to use a slightly modified Northwind database. The screen capture from SQL server management studio shows the change. I added a new column called Salary, inserted some random salaries for the employees and then turned off AllowNulls.   The reporting relationship for Northwind Employees is shown below.   The requirements for our application are as follows: Employees can see their LastName, FirstName, Title, Address and Salary Employees are allowed to edit only their Address information Employees can see the LastName, FirstName, Title, Address and Salary of their immediate reports Employees cannot see records of non immediate reports.  Employees are allowed to edit only the Salary and Title information of their immediate reports. Employees are not allowed to edit the Address of an immediate report Employees should be authenticated into the system. Employees by default get the “Employee” role. If a user has direct reports, they will also get assigned a “Manager” role. We use a very basic empId/pwd scheme of EmployeeID (1-9) and password test$1. You should never do this in an actual application. The application should protect from Cross Site Request Forgery (CSRF). For example, Michael could trick Steven, who is already logged on to the HR website, to load a page which contains a malicious request. where without Steven’s knowledge, a form on the site posts information back to the Northwind HR website using Steven’s credentials. Michael could use this technique to give himself a raise :-) UI Notes The layout of our app looks like so: When Nancy (EmpID 1) signs on, she sees the default page with her details and is allowed to edit her address. If Nancy attempts to view the record of employee Andrew who has an employeeID of 2 (Employees/Edit/2), she will get a “Not Authorized” error page. When Andrew (EmpID 2) signs on, he can edit the address field of his record and change the title and salary of employees that directly report to him. Implementation Notes All controllers inherit from a BaseController. The BaseController currently only has error handling code. When a user signs on, we check to see if they are in a Manager role. We then create a FormsAuthenticationTicket, encrypt it (including the roles that the employee belongs to) and add it to a cookie. private void SetAuthenticationCookie(int employeeID, List<string> roles) { HttpCookiesSection cookieSection = (HttpCookiesSection) ConfigurationManager.GetSection("system.web/httpCookies"); AuthenticationSection authenticationSection = (AuthenticationSection) ConfigurationManager.GetSection("system.web/authentication"); FormsAuthenticationTicket authTicket = new FormsAuthenticationTicket( 1, employeeID.ToString(), DateTime.Now, DateTime.Now.AddMinutes(authenticationSection.Forms.Timeout.TotalMinutes), false, string.Join("|", roles.ToArray())); String encryptedTicket = FormsAuthentication.Encrypt(authTicket); HttpCookie authCookie = new HttpCookie(FormsAuthentication.FormsCookieName, encryptedTicket); if (cookieSection.RequireSSL || authenticationSection.Forms.RequireSSL) { authCookie.Secure = true; } HttpContext.Current.Response.Cookies.Add(authCookie); } We read this cookie back in Global.asax and set the Context.User to be a new GenericPrincipal with the roles we assigned earlier. protected void Application_AuthenticateRequest(Object sender, EventArgs e){ if (Context.User != null) { string cookieName = FormsAuthentication.FormsCookieName; HttpCookie authCookie = Context.Request.Cookies[cookieName]; if (authCookie == null) return; FormsAuthenticationTicket authTicket = FormsAuthentication.Decrypt(authCookie.Value); string[] roles = authTicket.UserData.Split(new char[] { '|' }); FormsIdentity fi = (FormsIdentity)(Context.User.Identity); Context.User = new System.Security.Principal.GenericPrincipal(fi, roles); }} We ensure that a user has permissions to view a record by creating a custom attribute AuthorizeToViewID that inherits from ActionFilterAttribute. public class AuthorizeToViewIDAttribute : ActionFilterAttribute{ IEmployeeRepository employeeRepository = new EmployeeRepository(); public override void OnActionExecuting(ActionExecutingContext filterContext) { if (filterContext.ActionParameters.ContainsKey("id") && filterContext.ActionParameters["id"] != null) { if (employeeRepository.IsAuthorizedToView((int)filterContext.ActionParameters["id"])) { return; } } throw new UnauthorizedAccessException("The record does not exist or you do not have permission to access it"); }} We add the AuthorizeToView attribute to any Action method that requires authorization. [HttpPost][Authorize(Order = 1)]//To prevent CSRF[ValidateAntiForgeryToken(Salt = Globals.EditSalt, Order = 2)]//See AuthorizeToViewIDAttribute class[AuthorizeToViewID(Order = 3)] [ActionName("Edit")]public ActionResult Update(int id){ var employeeToEdit = employeeRepository.GetEmployee(id); if (employeeToEdit != null) { //Employees can edit only their address //A manager can edit the title and salary of their subordinate string[] whiteList = (employeeToEdit.IsSubordinate) ? new string[] { "Title", "Salary" } : new string[] { "Address" }; if (TryUpdateModel(employeeToEdit, whiteList)) { employeeRepository.Save(employeeToEdit); return RedirectToAction("Details", new { id = id }); } else { ModelState.AddModelError("", "Please correct the following errors."); } } return View(employeeToEdit);} The Authorize attribute is added to ensure that only authorized users can execute that Action. We use the TryUpdateModel with a white list to ensure that (a) an employee is able to edit only their Address and (b) that a manager is able to edit only the Title and Salary of a subordinate. This works in conjunction with the AuthorizeToViewIDAttribute. The ValidateAntiForgeryToken attribute is added (with a salt) to avoid CSRF. The Order on the attributes specify the order in which the attributes are executed. The Edit View uses the AntiForgeryToken helper to render the hidden token: ......<% using (Html.BeginForm()) {%><%=Html.AntiForgeryToken(NorthwindHR.Models.Globals.EditSalt)%><%= Html.ValidationSummary(true, "Please correct the errors and try again.") %><div class="editor-label"> <%= Html.LabelFor(model => model.LastName) %></div><div class="editor-field">...... The application uses View specific models for ease of model binding. public class EmployeeViewModel{ public int EmployeeID; [Required] [DisplayName("Last Name")] public string LastName { get; set; } [Required] [DisplayName("First Name")] public string FirstName { get; set; } [Required] [DisplayName("Title")] public string Title { get; set; } [Required] [DisplayName("Address")] public string Address { get; set; } [Required] [DisplayName("Salary")] [Range(500, double.MaxValue)] public decimal Salary { get; set; } public bool IsSubordinate { get; set; }} To help with displaying readonly/editable fields, we use a helper method. //Simple extension method to display a TextboxFor or DisplayFor based on the isEditable variablepublic static MvcHtmlString TextBoxOrLabelFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, bool isEditable){ if (isEditable) { return htmlHelper.TextBoxFor(expression); } else { return htmlHelper.DisplayFor(expression); }} The helper method is used in the view like so: <%=Html.TextBoxOrLabelFor(model => model.Title, Model.IsSubordinate)%> As mentioned in this post, there is a much easier way to update properties on an object. Download Demo Project VS 2008, ASP.NET MVC 2 RTM Remember to change the connectionString to point to your Northwind DB NorthwindHR.zip Feedback and bugs are always welcome :-)

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  • ASP.NET MVC 3: Implicit and Explicit code nuggets with Razor

    - by ScottGu
    This is another in a series of posts I’m doing that cover some of the new ASP.NET MVC 3 features: New @model keyword in Razor (Oct 19th) Layouts with Razor (Oct 22nd) Server-Side Comments with Razor (Nov 12th) Razor’s @: and <text> syntax (Dec 15th) Implicit and Explicit code nuggets with Razor (today) In today’s post I’m going to discuss how Razor enables you to both implicitly and explicitly define code nuggets within your view templates, and walkthrough some code examples of each of them.  Fluid Coding with Razor ASP.NET MVC 3 ships with a new view-engine option called “Razor” (in addition to the existing .aspx view engine).  You can learn more about Razor, why we are introducing it, and the syntax it supports from my Introducing Razor blog post. Razor minimizes the number of characters and keystrokes required when writing a view template, and enables a fast, fluid coding workflow. Unlike most template syntaxes, you do not need to interrupt your coding to explicitly denote the start and end of server blocks within your HTML. The Razor parser is smart enough to infer this from your code. This enables a compact and expressive syntax which is clean, fast and fun to type. For example, the Razor snippet below can be used to iterate a collection of products and output a <ul> list of product names that link to their corresponding product pages: When run, the above code generates output like below: Notice above how we were able to embed two code nuggets within the content of the foreach loop.  One of them outputs the name of the Product, and the other embeds the ProductID within a hyperlink.  Notice that we didn’t have to explicitly wrap these code-nuggets - Razor was instead smart enough to implicitly identify where the code began and ended in both of these situations.  How Razor Enables Implicit Code Nuggets Razor does not define its own language.  Instead, the code you write within Razor code nuggets is standard C# or VB.  This allows you to re-use your existing language skills, and avoid having to learn a customized language grammar. The Razor parser has smarts built into it so that whenever possible you do not need to explicitly mark the end of C#/VB code nuggets you write.  This makes coding more fluid and productive, and enables a nice, clean, concise template syntax.  Below are a few scenarios that Razor supports where you can avoid having to explicitly mark the beginning/end of a code nugget, and instead have Razor implicitly identify the code nugget scope for you: Property Access Razor allows you to output a variable value, or a sub-property on a variable that is referenced via “dot” notation: You can also use “dot” notation to access sub-properties multiple levels deep: Array/Collection Indexing: Razor allows you to index into collections or arrays: Calling Methods: Razor also allows you to invoke methods: Notice how for all of the scenarios above how we did not have to explicitly end the code nugget.  Razor was able to implicitly identify the end of the code block for us. Razor’s Parsing Algorithm for Code Nuggets The below algorithm captures the core parsing logic we use to support “@” expressions within Razor, and to enable the implicit code nugget scenarios above: Parse an identifier - As soon as we see a character that isn't valid in a C# or VB identifier, we stop and move to step 2 Check for brackets - If we see "(" or "[", go to step 2.1., otherwise, go to step 3  Parse until the matching ")" or "]" (we track nested "()" and "[]" pairs and ignore "()[]" we see in strings or comments) Go back to step 2 Check for a "." - If we see one, go to step 3.1, otherwise, DO NOT ACCEPT THE "." as code, and go to step 4 If the character AFTER the "." is a valid identifier, accept the "." and go back to step 1, otherwise, go to step 4 Done! Differentiating between code and content Step 3.1 is a particularly interesting part of the above algorithm, and enables Razor to differentiate between scenarios where an identifier is being used as part of the code statement, and when it should instead be treated as static content: Notice how in the snippet above we have ? and ! characters at the end of our code nuggets.  These are both legal C# identifiers – but Razor is able to implicitly identify that they should be treated as static string content as opposed to being part of the code expression because there is whitespace after them.  This is pretty cool and saves us keystrokes. Explicit Code Nuggets in Razor Razor is smart enough to implicitly identify a lot of code nugget scenarios.  But there are still times when you want/need to be more explicit in how you scope the code nugget expression.  The @(expression) syntax allows you to do this: You can write any C#/VB code statement you want within the @() syntax.  Razor will treat the wrapping () characters as the explicit scope of the code nugget statement.  Below are a few scenarios where we could use the explicit code nugget feature: Perform Arithmetic Calculation/Modification: You can perform arithmetic calculations within an explicit code nugget: Appending Text to a Code Expression Result: You can use the explicit expression syntax to append static text at the end of a code nugget without having to worry about it being incorrectly parsed as code: Above we have embedded a code nugget within an <img> element’s src attribute.  It allows us to link to images with URLs like “/Images/Beverages.jpg”.  Without the explicit parenthesis, Razor would have looked for a “.jpg” property on the CategoryName (and raised an error).  By being explicit we can clearly denote where the code ends and the text begins. Using Generics and Lambdas Explicit expressions also allow us to use generic types and generic methods within code expressions – and enable us to avoid the <> characters in generics from being ambiguous with tag elements. One More Thing….Intellisense within Attributes We have used code nuggets within HTML attributes in several of the examples above.  One nice feature supported by the Razor code editor within Visual Studio is the ability to still get VB/C# intellisense when doing this. Below is an example of C# code intellisense when using an implicit code nugget within an <a> href=”” attribute: Below is an example of C# code intellisense when using an explicit code nugget embedded in the middle of a <img> src=”” attribute: Notice how we are getting full code intellisense for both scenarios – despite the fact that the code expression is embedded within an HTML attribute (something the existing .aspx code editor doesn’t support).  This makes writing code even easier, and ensures that you can take advantage of intellisense everywhere. Summary Razor enables a clean and concise templating syntax that enables a very fluid coding workflow.  Razor’s ability to implicitly scope code nuggets reduces the amount of typing you need to perform, and leaves you with really clean code. When necessary, you can also explicitly scope code expressions using a @(expression) syntax to provide greater clarity around your intent, as well as to disambiguate code statements from static markup. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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  • Asynchronous Streaming in ASP.NET WebApi

    - by andresv
     Hi everyone, if you use the cool MVC4 WebApi you might encounter yourself in a common situation where you need to return a rather large amount of data (most probably from a database) and you want to accomplish two things: Use streaming so the client fetch the data as needed, and that directly correlates to more fetching in the server side (from our database, for example) without consuming large amounts of memory. Leverage the new MVC4 WebApi and .NET 4.5 async/await asynchronous execution model to free ASP.NET Threadpool threads (if possible).  So, #1 and #2 are not directly related to each other and we could implement our code fulfilling one or the other, or both. The main point about #1 is that we want our method to immediately return to the caller a stream, and that client side stream be represented by a server side stream that gets written (and its related database fetch) only when needed. In this case we would need some form of "state machine" that keeps running in the server and "knows" what is the next thing to fetch into the output stream when the client ask for more content. This technique is generally called a "continuation" and is nothing new in .NET, in fact using an IEnumerable<> interface and the "yield return" keyword does exactly that, so our first impulse might be to write our WebApi method more or less like this:           public IEnumerable<Metadata> Get([FromUri] int accountId)         {             // Execute the command and get a reader             using (var reader = GetMetadataListReader(accountId))             {                 // Read rows asynchronously, put data into buffer and write asynchronously                 while (reader.Read())                 {                     yield return MapRecord(reader);                 }             }         }   While the above method works, unfortunately it doesn't accomplish our objective of returning immediately to the caller, and that's because the MVC WebApi infrastructure doesn't yet recognize our intentions and when it finds an IEnumerable return value, enumerates it before returning to the client its values. To prove my point, I can code a test method that calls this method, for example:        [TestMethod]         public void StreamedDownload()         {             var baseUrl = @"http://localhost:57771/api/metadata/1";             var client = new HttpClient();             var sw = Stopwatch.StartNew();             var stream = client.GetStreamAsync(baseUrl).Result;             sw.Stop();             Debug.WriteLine("Elapsed time Call: {0}ms", sw.ElapsedMilliseconds); } So, I would expect the line "var stream = client.GetStreamAsync(baseUrl).Result" returns immediately without server-side fetching of all data in the database reader, and this didn't happened. To make the behavior more evident, you could insert a wait time (like Thread.Sleep(1000);) inside the "while" loop, and you will see that the client call (GetStreamAsync) is not going to return control after n seconds (being n == number of reader records being fetched).Ok, we know this doesn't work, and the question would be: is there a way to do it?Fortunately, YES!  and is not very difficult although a little more convoluted than our simple IEnumerable return value. Maybe in the future this scenario will be automatically detected and supported in MVC/WebApi.The solution to our needs is to use a very handy class named PushStreamContent and then our method signature needs to change to accommodate this, returning an HttpResponseMessage instead of our previously used IEnumerable<>. The final code will be something like this: public HttpResponseMessage Get([FromUri] int accountId)         {             HttpResponseMessage response = Request.CreateResponse();             // Create push content with a delegate that will get called when it is time to write out              // the response.             response.Content = new PushStreamContent(                 async (outputStream, httpContent, transportContext) =>                 {                     try                     {                         // Execute the command and get a reader                         using (var reader = GetMetadataListReader(accountId))                         {                             // Read rows asynchronously, put data into buffer and write asynchronously                             while (await reader.ReadAsync())                             {                                 var rec = MapRecord(reader);                                 var str = await JsonConvert.SerializeObjectAsync(rec);                                 var buffer = UTF8Encoding.UTF8.GetBytes(str);                                 // Write out data to output stream                                 await outputStream.WriteAsync(buffer, 0, buffer.Length);                             }                         }                     }                     catch(HttpException ex)                     {                         if (ex.ErrorCode == -2147023667) // The remote host closed the connection.                          {                             return;                         }                     }                     finally                     {                         // Close output stream as we are done                         outputStream.Close();                     }                 });             return response;         } As an extra bonus, all involved classes used already support async/await asynchronous execution model, so taking advantage of that was very easy. Please note that the PushStreamContent class receives in its constructor a lambda (specifically an Action) and we decorated our anonymous method with the async keyword (not a very well known technique but quite handy) so we can await over the I/O intensive calls we execute like reading from the database reader, serializing our entity and finally writing to the output stream.  Well, if we execute the test again we will immediately notice that the a line returns immediately and then the rest of the server code is executed only when the client reads through the obtained stream, therefore we get low memory usage and far greater scalability for our beloved application serving big chunks of data.Enjoy!Andrés.        

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  • General Purpose ASP.NET Data Source Control

    - by Ricardo Peres
    OK, you already know about the ObjectDataSource control, so what’s wrong with it? Well, for once, it doesn’t pass any context to the SelectMethod, you only get the parameters supplied on the SelectParameters plus the desired ordering, starting page and maximum number of rows to display. Also, you must have two separate methods, one for actually retrieving the data, and the other for getting the total number of records (SelectCountMethod). Finally, you don’t get a chance to alter the supplied data before you bind it to the target control. I wanted something simple to use, and more similar to ASP.NET 4.5, where you can have the select method on the page itself, so I came up with CustomDataSource. Here’s how to use it (I chose a GridView, but it works equally well with any regular data-bound control): 1: <web:CustomDataSourceControl runat="server" ID="datasource" PageSize="10" OnData="OnData" /> 2: <asp:GridView runat="server" ID="grid" DataSourceID="datasource" DataKeyNames="Id" PageSize="10" AllowPaging="true" AllowSorting="true" /> The OnData event handler receives a DataEventArgs instance, which contains some properties that describe the desired paging location and size, and it’s where you return the data plus the total record count. Here’s a quick example: 1: protected void OnData(object sender, DataEventArgs e) 2: { 3: //just return some data 4: var data = Enumerable.Range(e.StartRowIndex, e.PageSize).Select(x => new { Id = x, Value = x.ToString(), IsPair = ((x % 2) == 0) }); 5: e.Data = data; 6: //the total number of records 7: e.TotalRowCount = 100; 8: } Here’s the code for the DataEventArgs: 1: [Serializable] 2: public class DataEventArgs : EventArgs 3: { 4: public DataEventArgs(Int32 pageSize, Int32 startRowIndex, String sortExpression, IOrderedDictionary parameters) 5: { 6: this.PageSize = pageSize; 7: this.StartRowIndex = startRowIndex; 8: this.SortExpression = sortExpression; 9: this.Parameters = parameters; 10: } 11:  12: public IEnumerable Data 13: { 14: get; 15: set; 16: } 17:  18: public IOrderedDictionary Parameters 19: { 20: get; 21: private set; 22: } 23:  24: public String SortExpression 25: { 26: get; 27: private set; 28: } 29:  30: public Int32 StartRowIndex 31: { 32: get; 33: private set; 34: } 35:  36: public Int32 PageSize 37: { 38: get; 39: private set; 40: } 41:  42: public Int32 TotalRowCount 43: { 44: get; 45: set; 46: } 47: } As you can guess, the StartRowIndex and PageSize receive the starting row and the desired page size, where the page size comes from the PageSize property on the markup. There’s also a SortExpression, which gets passed the sorted-by column and direction (if descending) and a dictionary containing all the values coming from the SelectParameters collection, if any. All of these are read only, and it is your responsibility to fill in the Data and TotalRowCount. The code for the CustomDataSource is very simple: 1: [NonVisualControl] 2: public class CustomDataSourceControl : DataSourceControl 3: { 4: public CustomDataSourceControl() 5: { 6: this.SelectParameters = new ParameterCollection(); 7: } 8:  9: protected override DataSourceView GetView(String viewName) 10: { 11: return (new CustomDataSourceView(this, viewName)); 12: } 13:  14: internal void GetData(DataEventArgs args) 15: { 16: this.OnData(args); 17: } 18:  19: protected virtual void OnData(DataEventArgs args) 20: { 21: EventHandler<DataEventArgs> data = this.Data; 22:  23: if (data != null) 24: { 25: data(this, args); 26: } 27: } 28:  29: [Browsable(false)] 30: [DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)] 31: [PersistenceMode(PersistenceMode.InnerProperty)] 32: public ParameterCollection SelectParameters 33: { 34: get; 35: private set; 36: } 37:  38: public event EventHandler<DataEventArgs> Data; 39:  40: public Int32 PageSize 41: { 42: get; 43: set; 44: } 45: } Also, the code for the accompanying internal – as there is no need to use it from outside of its declaring assembly - data source view: 1: sealed class CustomDataSourceView : DataSourceView 2: { 3: private readonly CustomDataSourceControl dataSourceControl = null; 4:  5: public CustomDataSourceView(CustomDataSourceControl dataSourceControl, String viewName) : base(dataSourceControl, viewName) 6: { 7: this.dataSourceControl = dataSourceControl; 8: } 9:  10: public override Boolean CanPage 11: { 12: get 13: { 14: return (true); 15: } 16: } 17:  18: public override Boolean CanRetrieveTotalRowCount 19: { 20: get 21: { 22: return (true); 23: } 24: } 25:  26: public override Boolean CanSort 27: { 28: get 29: { 30: return (true); 31: } 32: } 33:  34: protected override IEnumerable ExecuteSelect(DataSourceSelectArguments arguments) 35: { 36: IOrderedDictionary parameters = this.dataSourceControl.SelectParameters.GetValues(HttpContext.Current, this.dataSourceControl); 37: DataEventArgs args = new DataEventArgs(this.dataSourceControl.PageSize, arguments.StartRowIndex, arguments.SortExpression, parameters); 38:  39: this.dataSourceControl.GetData(args); 40:  41: arguments.TotalRowCount = args.TotalRowCount; 42: arguments.MaximumRows = this.dataSourceControl.PageSize; 43: arguments.AddSupportedCapabilities(DataSourceCapabilities.Page | DataSourceCapabilities.Sort | DataSourceCapabilities.RetrieveTotalRowCount); 44: arguments.RetrieveTotalRowCount = true; 45:  46: if (!(args.Data is ICollection)) 47: { 48: return (args.Data.OfType<Object>().ToList()); 49: } 50: else 51: { 52: return (args.Data); 53: } 54: } 55: } As always, looking forward to hearing from you!

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