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  • Localized tables and Entity Framework

    - by Pyttroll
    Hi all, I have a scenario where I need to localized values of objects in my database. Let's say you have an application that can create animals, if the user is english the value of the "Name" property of an animal would be entered as "Cat" in the UI whereas it would be entered as "Chat" in french. The animal culture table would contain 2 records pointing to the same animal in the parent table. When reading values back, if the value of "Name" does not exist in the user culture the default value (value the object was originally created with) would be used. The following diagrams demonstrate how the data is stored in SQL: I'm trying to map this schema to an object model using the Entity Framework, I'm a bit confused as to what the best way to approach the problem. Is EF appropriate for this? Should I used EF4? This EF model will be used by .NET RIA Services. Thanks, Pierre-Yves Troel Ayuda Media Systems http://www.ayudasystems.com

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  • Disable Foreign Key Exposure in Entity Framework?

    - by davemackey
    When I originally created a Dynamic Data project I told it to expose the foreign keys, but now I can't make mappings between two entities b/c of the foreign keys. When I click on mapping details while focused on my association I receive the message: Mappings are not allow for an association over exposed foreign keys. So I'd like to disable the exposure of the foreign keys but am unsure how to do this without creating a new Entity Model from scratch. I'm not far along - so that wouldn't be hard, but I imagine there must be a programmatic switch for this?

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  • Using Entity Framework V4 - Mapping Stored Procedures with XML output

    - by ericwahner
    I have been attempting to implement the Entity framework into my project and unfortunately it seems like mapping an XML result set from SQL is not something that is supported. I also have issues with returning multiple result sets, though I understand that the EFExtensions was created to try to mitigate that issue. Is there a way to take a FOR XML EXPLICIT result from a SQL Stored Procedure and map it using the Entity Framework?

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  • Entity framework support for table valued functions and thus full text

    - by simonsabin
    One of my most popular posts with over 10, 000 hits is how to enable full text when using LINQ to SQL http://sqlblogcasts.com/blogs/simons/archive/2008/12/18/LINQ-to-SQL---Enabling-Fulltext-searching.aspx , core to this is the use of a table valued function. I’m therefore interested to see that Entity Framework will support table valued functions in the next release for more details have a read of the efdesign blog http://blogs.msdn.com/b/efdesign/archive/2011/01/21/table-valued-function-support...(read more)

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  • generate only objectLayer of Entity Framework Model by edmgen tool

    - by loviji
    How to generate only objectLayer by edmgen tool, without generating csdl, ssdl and views ? *"%windir%\Microsoft.NET\Framework\v4.0.30319\edmgen.exe" /mode:fullgeneration /c:"Data Source=.\sqlexpress; Initial Catalog=uqs; Integrated Security=SSPI" /project:generateEntityModel /entitycontainer:uqsEntities /namespace:uqsModel /language:CSharp /outobjectlayer:"D:/uqsObjectLayer.cs" * in this script I don't write location to write csdl, ssdl and views , but they are generated in C:\Users\adminUser in windows Vista and objectLayer generated to D:/uqsObjectLayer.cs. If I use /mode:EntityClassGeneration, this option requires the /incsdl argument and either the /project argument or the /outobjectlayer argument. The /language argument is optional. But I don't want use csdl file. As I understand, edmgen.tool can not create objectlayer without csdl file. Now is there alternate way or tool for generating objectlayer from db?

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  • Save entity with entity framework

    - by Michel
    Hi, I'm saving entities/records with the EF, but i'm curious if there is another way of doing it. I receive a class from a MVC controller method, so basicly i have all the info: the class's properties, including the primary key. Without EF i would do a Sql update (update table set a=b, c=d where id = 5), but with EF i got no further than this: Get an object with ID of 5 Update the (existing) object with the new object Submitchanges. What bothers me is that i have to get the object from the database first, where i have all the info to do an update statement. Is there another way of doing this?

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  • Entity Framework Update Entity along with child entities (add/update as necessary)

    - by Jorin
    I have a many-to-many relationship between Issues and Scopes in my EF Context. In ASP.NET MVC, I bring up an Edit form that allows the user to edit a particular Issue. At the bottom of the form, is a list of checkboxes that allow them to select which scopes apply to this issue. When editing an issue, it likely will always have some Scopes associated with it already--these boxes will be checked already. However, the user has the opportunity to check more scopes or remove some of the currently checked scopes. My code looked something like this to save just the Issue: using (var edmx = new MayflyEntities()) { Issue issue = new Issue { IssueID = id, TSColumn = formIssue.TSColumn }; edmx.Issues.Attach(issue); UpdateModel(issue); if (ModelState.IsValid) { //if (edmx.SaveChanges() != 1) throw new Exception("Unknown error. Please try again."); edmx.SaveChanges(); TempData["message"] = string.Format("Issue #{0} successfully modified.", id); } } So, when I try to add in the logic to save the associated scopes, I tried several things, but ultimately, this is what made the most sense to me: using (var edmx = new MayflyEntities()) { Issue issue = new Issue { IssueID = id, TSColumn = formIssue.TSColumn }; edmx.Issues.Attach(issue); UpdateModel(issue); foreach (int scopeID in formIssue.ScopeIDs) { var thisScope = new Scope { ID = scopeID }; edmx.Scopes.Attach(thisScope); thisScope.ProjectID = formIssue.ProjectID; if (issue.Scopes.Contains(thisScope)) { issue.Scopes.Attach(thisScope); //the scope already exists } else { issue.Scopes.Add(thisScope); // the scope needs to be added } } if (ModelState.IsValid) { //if (edmx.SaveChanges() != 1) throw new Exception("Unknown error. Please try again."); edmx.SaveChanges(); TempData["message"] = string.Format("Issue #{0} successfully modified.", id); } } But, unfortunately, that just throws the following exception: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. What am I doing wrong?

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  • Entity Framework - Insert/Update new entity with child-entities

    - by Christina Mayers
    I have found many questions here on SO and articles all over the internet but none really tackled my problem. My model looks like this (I striped all non essential Properties): Everyday or so "Play" gets updated (via a XML-file containing the information). internal Play ParsePlayInfo(XDocument doc) { Play play = (from p in doc.Descendants("Play") select new Play { Theatre = new Theatre() { //Properties }, //Properties LastUpdate = DateTime.Now }).SingleOrDefault(); var actors = (from a in doc.XPathSelectElement(".//Play//Actors").Nodes() select new Lecturer() { //Properties }); var parts = (from p in doc.XPathSelectElement(".//Play//Parts").Nodes() select new Part() { //Properties }).ToList(); foreach (var item in parts) { play.Parts.Add(item); } var reviews = (from r in doc.XPathSelectElement(".//Play//Reviews").Nodes() select new Review { //Properties }).ToList(); for (int i = 0; i < reviews.Count(); i++) { PlayReviews pR = new PlayReviews() { Review = reviews[i], Play = play, //Properties }; play.PlayReviews.Add(pR); } return play; } If I add this "play" via Add() every Childobject of Play will be inserted - regardless if some exist already. Since I need to update existing entries I have to do something about that. As far as I can tell I have the following options: add/update the child entities in my PlayRepositories Add-Method restructure and rewrite ParsePlayInfo() so that get all the child entities first, add or update them and then create a new Play. The only problem I have here is that I wanted ParsePlayInfo() to be persistence ignorant, I could work around this by creating multiple parse methods (eg ParseActors() ) and assign them to play in my controller (I'm using ASP.net MVC) after everything was parsed and added Currently I am implementing option 1 - but it feels wrong. I'd appreciate it if someone could guide me in the right direction on this one.

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  • How to implement EntityDataSource Where IN entity sql clause

    - by TonyS
    I want to pass a number of values into a parameter of the EntityDataSource, e.g.: Where="it.ORDER_ID IN {@OrderIdList}" (this is a property on the EntityDataSource) <WhereParameters> <asp:ControlParameter Name="OrderIdList" Type="Int16" ControlID="OrderFilterControl" PropertyName="OrderIdList" /> </WhereParameters> This doesn't work as ORDER_ID is of type int32 and I need to pass in multiple values, e.g. {1,2,3} etc The next thing I tried was setting the Where clause in code-behind and this all works except I can't get data binding on DropDownLists to work. By this I mean no value is returned from the bound dropdownlists in the EntityDataSource Updating Event. My ideal solution would be to use a WhereParameter on the EntityDataSource but any help is appreciated. Thanks, Tony. A complete code example follows using the AdventureWorks db: Public Class EntityDataSourceWhereInClause Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load CustomersEntityDataSource.Where = WhereClause ''# reset after each postback as its lost otherwise End Sub Private Sub cmdFilterCustomers_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdFilterCustomers.Click Dim CustomerIdList As New Generic.List(Of Int32) For Each item As ListItem In CustomerIdCheckBoxList.Items If item.Selected Then CustomerIdList.Add(item.Value) End If Next Dim CustomerCsvList As String = String.Join(", ", CustomerIdList.Select(Function(o) o.ToString()).ToArray()) WhereClause = "it.CustomerID IN {" & CustomerCsvList & "}" CustomersEntityDataSource.Where = WhereClause FormView1.PageIndex = 0 End Sub ''# save between postbacks the custom Where IN clause Public Property WhereClause() As String Get Return ViewState("WhereClause") End Get Set(ByVal value As String) ViewState.Add("WhereClause", value) End Set End Property Private Sub CustomersEntityDataSource_Updating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.EntityDataSourceChangingEventArgs) Handles CustomersEntityDataSource.Updating Dim c = CType(e.Entity, EntityFrameworkTest.Customer) If c.Title.Length = 0 Then Response.Write("Title is empty string, so will save like this!") End If End Sub End Class <%@ Page Language="vb" AutoEventWireup="false" CodeBehind="EntityDataSourceWhereInClause.aspx.vb" Inherits="EntityFrameworkTest.EntityDataSourceWhereInClause" %> <!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 runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <%''# filter control %> <div> <asp:EntityDataSource ID="CustomerIdListEntityDataSource" runat="server" ConnectionString="name=AdventureWorksLT2008Entities" DefaultContainerName="AdventureWorksLT2008Entities" EnableFlattening="False" EntitySetName="Customers" Select="it.[CustomerID]" OrderBy="it.[CustomerID]"> </asp:EntityDataSource> <asp:CheckBoxList ID="CustomerIdCheckBoxList" runat="server" DataSourceID="CustomerIdListEntityDataSource" DataTextField="CustomerID" DataValueField="CustomerID" RepeatDirection="Horizontal"> </asp:CheckBoxList> <asp:Button ID="cmdFilterCustomers" runat="server" Text="Apply Filter" /> </div> <% ''# you get this error passing in CSV in the where clause ''# The element type 'Edm.Int32' and the CollectionType 'Transient.collection[Edm.String(Nullable=True,DefaultValue=,MaxLength=,Unicode=,FixedLength=)]' are not compatible. The IN expression only supports entity, primitive, and reference types. Near WHERE predicate, line 6, column 15. ''# so have coded it manually in code-behind Where="it.CustomerID IN {@OrderIdList}" %> <asp:EntityDataSource ID="CustomersEntityDataSource" runat="server" ConnectionString="name=AdventureWorksLT2008Entities" DefaultContainerName="AdventureWorksLT2008Entities" EnableFlattening="False" EnableUpdate="True" EntitySetName="Customers" AutoGenerateOrderByClause="false"> </asp:EntityDataSource> <%''# updating works with DropDownLists until the Where clause is set in code %> <asp:FormView ID="FormView1" runat="server" AllowPaging="True" CellPadding="4" DataKeyNames="CustomerID" DataSourceID="CustomersEntityDataSource" ForeColor="#333333"> <EditItemTemplate> CustomerID: <asp:Label ID="CustomerIDLabel1" runat="server" Text='<%# Eval("CustomerID") %>' /> <br /> NameStyle: <asp:CheckBox ID="NameStyleCheckBox" runat="server" Checked='<%# Bind("NameStyle") %>' /> <br /> Title: <%''# the SelectedValue is not Bound to the EF object if the Where clause is updated in code-behind %> <asp:DropDownList ID="ddlTitleBound" runat="server" DataSourceID="TitleEntityDataSource" DataTextField="Title" DataValueField="Title" AutoPostBack="false" AppendDataBoundItems="true" SelectedValue='<%# Bind("Title") %>'> </asp:DropDownList> <asp:EntityDataSource ID="TitleEntityDataSource" runat="server" ConnectionString="name=AdventureWorksLT2008Entities" DefaultContainerName="AdventureWorksLT2008Entities" EnableFlattening="False" EntitySetName="Customers" Select="it.[Title]" GroupBy="it.[Title]" ViewStateMode="Enabled"> </asp:EntityDataSource> <br /> FirstName: <asp:TextBox ID="FirstNameTextBox" runat="server" Text='<%# Bind("FirstName") %>' /> <br /> MiddleName: <asp:TextBox ID="MiddleNameTextBox" runat="server" Text='<%# Bind("MiddleName") %>' /> <br /> LastName: <asp:TextBox ID="LastNameTextBox" runat="server" Text='<%# Bind("LastName") %>' /> <br /> Suffix: <asp:TextBox ID="SuffixTextBox" runat="server" Text='<%# Bind("Suffix") %>' /> <br /> CompanyName: <asp:TextBox ID="CompanyNameTextBox" runat="server" Text='<%# Bind("CompanyName") %>' /> <br /> SalesPerson: <asp:TextBox ID="SalesPersonTextBox" runat="server" Text='<%# Bind("SalesPerson") %>' /> <br /> EmailAddress: <asp:TextBox ID="EmailAddressTextBox" runat="server" Text='<%# Bind("EmailAddress") %>' /> <br /> Phone: <asp:TextBox ID="PhoneTextBox" runat="server" Text='<%# Bind("Phone") %>' /> <br /> PasswordHash: <asp:TextBox ID="PasswordHashTextBox" runat="server" Text='<%# Bind("PasswordHash") %>' /> <br /> PasswordSalt: <asp:TextBox ID="PasswordSaltTextBox" runat="server" Text='<%# Bind("PasswordSalt") %>' /> <br /> rowguid: <asp:TextBox ID="rowguidTextBox" runat="server" Text='<%# Bind("rowguid") %>' /> <br /> ModifiedDate: <asp:TextBox ID="ModifiedDateTextBox" runat="server" Text='<%# Bind("ModifiedDate") %>' /> <br /> <asp:LinkButton ID="UpdateButton" runat="server" CausesValidation="True" CommandName="Update" Text="Update" /> &nbsp;<asp:LinkButton ID="UpdateCancelButton" runat="server" CausesValidation="False" CommandName="Cancel" Text="Cancel" /> </EditItemTemplate> <EditRowStyle BackColor="#999999" /> <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /> <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" /> <ItemTemplate> CustomerID: <asp:Label ID="CustomerIDLabel" runat="server" Text='<%# Eval("CustomerID") %>' /> <br /> NameStyle: <asp:CheckBox ID="NameStyleCheckBox" runat="server" Checked='<%# Bind("NameStyle") %>' Enabled="false" /> <br /> Title: <asp:Label ID="TitleLabel" runat="server" Text='<%# Bind("Title") %>' /> <br /> FirstName: <asp:Label ID="FirstNameLabel" runat="server" Text='<%# Bind("FirstName") %>' /> <br /> MiddleName: <asp:Label ID="MiddleNameLabel" runat="server" Text='<%# Bind("MiddleName") %>' /> <br /> LastName: <asp:Label ID="LastNameLabel" runat="server" Text='<%# Bind("LastName") %>' /> <br /> Suffix: <asp:Label ID="SuffixLabel" runat="server" Text='<%# Bind("Suffix") %>' /> <br /> CompanyName: <asp:Label ID="CompanyNameLabel" runat="server" Text='<%# Bind("CompanyName") %>' /> <br /> SalesPerson: <asp:Label ID="SalesPersonLabel" runat="server" Text='<%# Bind("SalesPerson") %>' /> <br /> EmailAddress: <asp:Label ID="EmailAddressLabel" runat="server" Text='<%# Bind("EmailAddress") %>' /> <br /> Phone: <asp:Label ID="PhoneLabel" runat="server" Text='<%# Bind("Phone") %>' /> <br /> PasswordHash: <asp:Label ID="PasswordHashLabel" runat="server" Text='<%# Bind("PasswordHash") %>' /> <br /> PasswordSalt: <asp:Label ID="PasswordSaltLabel" runat="server" Text='<%# Bind("PasswordSalt") %>' /> <br /> rowguid: <asp:Label ID="rowguidLabel" runat="server" Text='<%# Bind("rowguid") %>' /> <br /> ModifiedDate: <asp:Label ID="ModifiedDateLabel" runat="server" Text='<%# Bind("ModifiedDate") %>' /> <br /> <asp:LinkButton ID="EditButton" runat="server" CausesValidation="False" CommandName="Edit" Text="Edit" /> </ItemTemplate> <PagerSettings Position="Top" /> <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" /> <RowStyle BackColor="#F7F6F3" ForeColor="#333333" /> </asp:FormView> </form>

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  • Unit Testing in Entity Framework 4 - using CreateSourceQuery

    - by Adam
    There are many great tutorials on abstracting your EF4 context so that it can be tested against (without involving a DB). Two great (and similar) examples are here: http://blogs.msdn.com/b/adonet/archive/2009/12/17/walkthrough-test-driven-development-with-the-entity-framework-4-0.aspx (oops, not enough rep. points to post second URL) basically you wind up querying your repository using linq-to-objects while testing, and linq-to-entities while running, and usually they behave the same, but when you start hitting more advanced functionality, problems arise. Here's the question. When using linq-to-objects against IObjectSet (ie, unit testing), CreateSourceQuery returns null, which will probably cause your entire query to crash and burn. ie O = db.Orders.First(); O.OrderItems.CreateSourceQuery().ToList(); Is there a way to get CreateSourceQuery to just return the underlying collection, rather than null when working with collections? Unfortunately EntityCollection is sealed, and so cannot be mocked. This isn't really the end or the world if EF4 won't let you abstract things to this level, I just wanted to make sure there wasn't something I was missing.

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  • Entity Framework 4 and SYSUTCDATETIME ()

    - by GIbboK
    Hi, I use EF4 and C#. I have a Table in my DataBase (MS SQL 2008) with a default value for a column SYSUTCDATETIME (). The Idea is to automatically add Date and Time as soon as a new record is Created. I create my Conceptual Model using EF4, and I have created an ASP.PAGE with a DetailsView Control in INSERT MODE. My problems: When I create a new Record. EF is not able to insert the actual Date and Time value but it inserts instead this value 0001-01-01 00:00:00.00. I suppose the EF is not able to use SYSUTCDATETIME () defined in my DataBase Any idea how to solve it? Thanks Here my SQL script CREATE TABLE dbo.CmsAdvertisers ( AdvertiserId int NOT NULL IDENTITY CONSTRAINT PK_CmsAdvertisers_AdvertiserId PRIMARY KEY, DateCreated dateTime2(2) NOT NULL CONSTRAINT DF_CmsAdvertisers_DateCreated DEFAULT sysutcdatetime (), ReferenceAdvertiser varchar(64) NOT NULL, NoteInternal nvarchar(256) NOT NULL CONSTRAINT DF_CmsAdvertisers_NoteInternal DEFAULT '' ); My Temporary solution: Please guys help me on this e.Values["DateCreated"] = DateTime.UtcNow; More info here: http://msdn.microsoft.com/en-us/library/bb387157.aspx How to use the default Entity Framework and default date values http://msdn.microsoft.com/en-us/library/dd296755.aspx

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  • Mapping composite foreign keys in a many-many relationship in Entity Framework

    - by Kirk Broadhurst
    I have a Page table and a View table. There is a many-many relationship between these two via a PageView table. Unfortunately all of these tables need to have composite keys (for business reasons). Page has a primary key of (PageCode, Version), View has a primary key of (ViewCode, Version). PageView obviously enough has PageCode, ViewCode, and Version. The FK to Page is (PageCode, Version) and the FK to View is (ViewCode, Version) Makes sense and works, but when I try to map this in Entity framework I get Error 3021: Problem in mapping fragments...: Each of the following columns in table PageView is mapped to multiple conceptual side properties: PageView.Version is mapped to (PageView_Association.View.Version, PageView_Association.Page.Version) So clearly enough, EF is having a complain about the Version column being a common component of the two foreign keys. Obviously I could create a PageVersion and ViewVersion column in the join table, but that kind of defeats the point of the constraint, i.e. the Page and View must have the same Version value. Has anyone encountered this, and is there anything I can do get around it? Thanks!

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  • Entity Framework - Store parent reference on child relationship (one -> many)

    - by contactmatt
    I have a setup like this: [Table("tablename...")] public class Branch { public Branch() { Users = new List<User>(); } [Key] public int Id { get; set; } public string Name { get; set; } public List<User> Users { get; set; } } [Table("tablename...")] public class User { [Key] public int Id {get; set; } public string Username { get; set; } public string Password { get; set; } [ForeignKey("ParentBranch")] public int? ParentBranchId { get; set; } // Is this possible? public Branch ParentBranch { get; set; } // ??? } Is it possible for the User to know what parent branch it belongs to? The code above is not working. Entity Framework version 5.0 .NET 4.0 c#

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  • Entity Framework POCO objects

    - by Dan
    I'm struggling with understanding Entity Framework and POCO objects. Here's what I'm trying to achieve. 1) Separate the DAL from the Business Layer by having my business layer use an interface to my DAL. Maybe use Unity to create my context. 2) Use Entity Framework inside my DAL. I have a Domain model with objects that reside in my business layer. I also have a database full of tables that doesn't really represent my domain model. I setup Entity Framework and generated POCO objects by using the ADO.NET POCO Generator extension. This gave me an object for each table in my database. Now I want to be able to say context.GetAll<User>(); and have it return a list of my User objects. The User object is in my business layer. Is that possible? Does that make sense or am I totally off and should start over? I'm guessing I need to use the repository pattern to achieve this, but I'm not sure. Can anyone help?

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  • Need advice on framework design: how to make extending easy

    - by beginner_
    I'm creating a framework/library for a rather specific use-case (data type). It uses diverse spring components, including spring-data. The library has a set of entity classes properly set up and according service and dao layers. The main work or main benefit of the framework lies in the dao and service layer. Developers using the framework should be able to extend my entity classes to add additional fields they require. Therefore I made dao and service layer generic so it can be used by such extended entity classes. I now face an issue in the IO part of the framework. It must be able to import the according "special data type" into the database. In this part I need to create a new entity instance and hence need the actual class used. My current solution is to configure in spring a bean of the actual class used. The problem with this is that an application using the framework could only use 1 implementation of the entity (the original one from me or exactly 1 subclass but not 2 different classes of the same hierarchy. I'm looking for suggestions / desgins for solving this issue. Any ideas?

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  • Entity Framework Code First: Get Entities From Local Cache or the Database

    - by Ricardo Peres
    Entity Framework Code First makes it very easy to access local (first level) cache: you just access the DbSet<T>.Local property. This way, no query is sent to the database, only performed in already loaded entities. If you want to first search local cache, then the database, if no entries are found, you can use this extension method: 1: public static class DbContextExtensions 2: { 3: public static IQueryable<T> LocalOrDatabase<T>(this DbContext context, Expression<Func<T, Boolean>> expression) where T : class 4: { 5: IEnumerable<T> localResults = context.Set<T>().Local.Where(expression.Compile()); 6:  7: if (localResults.Any() == true) 8: { 9: return (localResults.AsQueryable()); 10: } 11:  12: IQueryable<T> databaseResults = context.Set<T>().Where(expression); 13:  14: return (databaseResults); 15: } 16: }

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  • Entity System and rendering

    - by hayer
    Okey, what I know so far; The entity contains a component(data-storage) which holds information like; - Texture/sprite - Shader - etc And then I have a renderer system which draws all this. But what I don't understand is how the renderer should be designed. Should I have one component for each "visual type". One component without shader, one with shader, etc? Just need some input on whats the "correct way" to do this. Tips and pitfalls to watch out for.

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  • Validation framework for .NET Compact Framework 3.5.

    - by Michal Drozdowicz
    Do you know of a fast and simple entity validation framework that could be used in a Compact Framework project? I've done some experiments with FluentValidation (using db4o System.Linq.Expressions, but it's rather slow) and EViL (but it seems a bit half-baked). Can you suggest any other or maybe point me to some resources on how to design such a framework so that it's both easy to use and performant?

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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 2 – Table per Type (TPT)

    - by mortezam
    In the previous blog post you saw that there are three different approaches to representing an inheritance hierarchy and I explained Table per Hierarchy (TPH) as the default mapping strategy in EF Code First. We argued that the disadvantages of TPH may be too serious for our design since it results in denormalized schemas that can become a major burden in the long run. In today’s blog post we are going to learn about Table per Type (TPT) as another inheritance mapping strategy and we'll see that TPT doesn’t expose us to this problem. Table per Type (TPT)Table per Type is about representing inheritance relationships as relational foreign key associations. Every class/subclass that declares persistent properties—including abstract classes—has its own table. The table for subclasses contains columns only for each noninherited property (each property declared by the subclass itself) along with a primary key that is also a foreign key of the base class table. This approach is shown in the following figure: For example, if an instance of the CreditCard subclass is made persistent, the values of properties declared by the BillingDetail base class are persisted to a new row of the BillingDetails table. Only the values of properties declared by the subclass (i.e. CreditCard) are persisted to a new row of the CreditCards table. The two rows are linked together by their shared primary key value. Later, the subclass instance may be retrieved from the database by joining the subclass table with the base class table. TPT Advantages The primary advantage of this strategy is that the SQL schema is normalized. In addition, schema evolution is straightforward (modifying the base class or adding a new subclass is just a matter of modify/add one table). Integrity constraint definition are also straightforward (note how CardType in CreditCards table is now a non-nullable column). Another much more important advantage is the ability to handle polymorphic associations (a polymorphic association is an association to a base class, hence to all classes in the hierarchy with dynamic resolution of the concrete class at runtime). A polymorphic association to a particular subclass may be represented as a foreign key referencing the table of that particular subclass. Implement TPT in EF Code First We can create a TPT mapping simply by placing Table attribute on the subclasses to specify the mapped table name (Table attribute is a new data annotation and has been added to System.ComponentModel.DataAnnotations namespace in CTP5): public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } [Table("BankAccounts")] public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } } [Table("CreditCards")] public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } } public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; } } If you prefer fluent API, then you can create a TPT mapping by using ToTable() method: protected override void OnModelCreating(ModelBuilder modelBuilder) {     modelBuilder.Entity<BankAccount>().ToTable("BankAccounts");     modelBuilder.Entity<CreditCard>().ToTable("CreditCards"); } Generated SQL For QueriesLet’s take an example of a simple non-polymorphic query that returns a list of all the BankAccounts: var query = from b in context.BillingDetails.OfType<BankAccount>() select b; Executing this query (by invoking ToList() method) results in the following SQL statements being sent to the database (on the bottom, you can also see the result of executing the generated query in SQL Server Management Studio): Now, let’s take an example of a very simple polymorphic query that requests all the BillingDetails which includes both BankAccount and CreditCard types: projects some properties out of the base class BillingDetail, without querying for anything from any of the subclasses: var query = from b in context.BillingDetails             select new { b.BillingDetailId, b.Number, b.Owner }; -- var query = from b in context.BillingDetails select b; This LINQ query seems even more simple than the previous one but the resulting SQL query is not as simple as you might expect: -- As you can see, EF Code First relies on an INNER JOIN to detect the existence (or absence) of rows in the subclass tables CreditCards and BankAccounts so it can determine the concrete subclass for a particular row of the BillingDetails table. Also the SQL CASE statements that you see in the beginning of the query is just to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type) TPT ConsiderationsEven though this mapping strategy is deceptively simple, the experience shows that performance can be unacceptable for complex class hierarchies because queries always require a join across many tables. In addition, this mapping strategy is more difficult to implement by hand— even ad-hoc reporting is more complex. This is an important consideration if you plan to use handwritten SQL in your application (For ad hoc reporting, database views provide a way to offset the complexity of the TPT strategy. A view may be used to transform the table-per-type model into the much simpler table-per-hierarchy model.) SummaryIn this post we learned about Table per Type as the second inheritance mapping in our series. So far, the strategies we’ve discussed require extra consideration with regard to the SQL schema (e.g. in TPT, foreign keys are needed). This situation changes with the Table per Concrete Type (TPC) that we will discuss in the next post. References ADO.NET team blog Java Persistence with Hibernate book a { text-decoration: none; } a:visited { color: Blue; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } p.MsoNormal { margin-top: 0in; margin-right: 0in; margin-bottom: 10.0pt; margin-left: 0in; line-height: 115%; font-size: 11.0pt; font-family: "Calibri" , "sans-serif"; }

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  • Any good C++ Component/Entity frameworks?

    - by Pat
    (Skip to the bold if you want to get straight to my question :) ) I've been dabbling in the different technologies available out there to use. I tried Unity and component based design, managing to get a little guy up and running around a map with basic pathfinding. I really loved how easy it was to program using components, but I wanted a bit more control and something more 2D friendly, so I went with LibGDX. I looked around and found 2 good frameworks for Java, which are Artemis and Apollo. I didn't like Artemis much, so I went with Apollo, which I loved. I managed to integrate it with Box2D and get a little guy running around bouncing balls. Great! But since I want to try out most of the options, there is still C++/SFML that I haven't tried yet. Coming from a Java/C# background, I've always wanted to get my hands dirty with C++. But then, after some looking around, I noticed there aren't any Component-Based frameworks for me to use. There's a somewhat done porting of Artemis, but, aside from not being completely finished, I didn't quite like Artemis even in Java. I found Apollo's approach much more.. logical. So, my question is, are there any good Component/Entity frameworks for C++ that I can use that are similar to Artemis, or preferably, Apollo?

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  • Cyclic References and WCF

    - by Kunal
    I have generated my POCO entities using POCO Generator, I have more than 150+ tables in my database. I am sharing POCO entities all across the application layers including the client. I have disabled both LazyLoading and ProxyCreation in my context.I am using WCF on top of my data access and business layer. Now, When I return a poco entity to my client, I get an error saying "Underlying connection was closed" I enabled WCF tracing and found the exact error : Contains cycles and cannot be serialized if reference tracking is disabled. I Looked at MSDN and found solutions like setting IsReference=true in the DataContract method atttribute but I am not decorating my POCO classes with DataContracts and I assume there is no need of it as well. I won't be calling that as a POCO if I decorate a class with DataContract attribute Then, I found solutions like applying custom attribute [CyclicReferenceAware] over my ServiceContracts.That did work but I wanted to throw this question to community to see how other people managed this and also why Microsoft didn't give built in support for figuring out cyclic references while serializing POCO classes

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  • Entity Framework and layer separation

    - by Thomas
    I'm trying to work a bit with Entity Framework and I got a question regarding the separation of layers. I usually use the UI - BLL - DAL approach and I'm wondering how to use EF here. My DAL would usually be something like GetPerson(id) { // some sql return new Person(...) } BLL: GetPerson(id) { Return personDL.GetPerson(id) } UI: Person p = personBL.GetPerson(id) My question now is: since EF creates my model and DAL, is it a good idea to wrap EF inside my own DAL or is it just a waste of time? If I don't need to wrap EF would I still place my Model.esmx inside its own class library or would it be fine to just place it inside my BLL and work some there? I can't really see the reason to wrap EF inside my own DAL but I want to know what other people are doing. So instead of having the above, I would leave out the DAL and just do: BLL: GetPerson(id) { using (TestEntities context = new TestEntities()) { var result = from p in context.Persons.Where(p => p.Id = id) select p; } } What to do?

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  • Entity communication: Message queue vs Publish/Subscribe vs Signal/Slots

    - by deft_code
    How do game engine entities communicate? Two use cases: How would entity_A send a take-damage message to entity_B? How would entity_A query entity_B's HP? Here's what I've encountered so far: Message queue entity_A creates a take-damage message and posts it to entity_B's message queue. entity_A creates a query-hp message and posts it to entity_B. entity_B in return creates an response-hp message and posts it to entity_A. Publish/Subscribe entity_B subscribes to take-damage messages (possibly with some preemptive filtering so only relevant message are delivered). entity_A produces take-damage message that references entity_B. entity_A subscribes to update-hp messages (possibly filtered). Every frame entity_B broadcasts update-hp messages. Signal/Slots ??? entity_A connects an update-hp slot to entity_B's update-hp signal. Something better? Do I have a correct understanding of how these communication schemes would tie into a game engine's entity system? How do entities in commercial game engines communicate?

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  • Entity Framework 4 "Generate Database from Model" to SQLEXPRESS mdf results in "Could not locate ent

    - by InfinitiesLoop
    I'm using Visual Studio 2010 RTM. I want to do model-first, so I started a new MVC app and added a new blank edmx. Created a few entities. No problem. Then I "Generate Database from Model", and allow the dialog to create a new database for me, which it does successfully as 'mydatabase.mdf' in the app's App_Data directory. Then I open the generated sql file (in Visual Studio). To run it of course I have to give it a connection. I am not sure if it's right, but I used '.\SQLEXPRESS' and Windows authentication. No idea how I'd tell it where the MDF is. Then the problem -- upon executing it, I get: Msg 911, Level 16, State 1, Line 1 Could not locate entry in sysdatabases for database 'mydatabase'. No entry found with that name. Make sure that the name is entered correctly. And indeed there were no tables created in the MDF. So... what am I doing wrong, or am I off my rocker expecting this to work? :)

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  • UDF call in entity framework is cached

    - by Fred Yang
    I am doing a test after reading an article http://blogs.msdn.com/alexj/archive/2009/08/07/tip-30-how-to-use-a-custom-store-function.aspx about udf function called. When I use a function with objectContext.Entities.Where( t= udf(para1, para2) == 1), here the Entities is not ObjectQuery, but an ObjectSet, the first time I call the method, it runs correctly, if I reuse the objectContext,and run it again but with different para1, para2, then the previous parameter values still cached, and the result is same as previous one, which is wrong. The sql profiler shows that both query hit the database, but the t-sql is the same. Am I missing something? And the ObjectSet does not support .where(esql_string). How to get udf working with ObjectSet? Thanks Fred

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