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• Alternatives to the Entity Framework for Serving/Consuming an OData Interface

  - by Egahn

  I'm researching how to set up an OData interface to our database. I would like to be able to pull/query data from our DB into Excel, as a start. Eventually I would like to have Excel run queries and pull data over HTTP from a remote client, including authentication, etc. I've set up a working (rickety) prototype so far, using the ADO.NET Entity Data Model wizard in Visual Studio, and VSTO to create a test Excel worksheet with a button to pull from that ADO.NET interface. This works OK so far, and I can query the DB using Linq through the entities/objects that are created by the ADO.NET EDM wizard. However, I have started to run into some problems with this approach. I've been finding the Entity Framework difficult to work with (and in fact, also difficult to research solutions to, as there's a lot of chaff out there regarding it and older versions of it). An example of this is my being unable to figure out how to set the SQL command timeout (as opposed to the HTTP request timeout) on the DataServiceContext object that the wizard generates for my schema, but that's not the point of my question. The real question I have is, if I want to use OData as my interface standard, am I stuck with the Entity Framework? Are there any other solutions out there (preferably open source) which can set up, serve and consume an OData interface, and are easier to work with and less bloated than the Entity Framework? I have seen mention of NHibernate as an alternative, but most of the comparison threads I've seen are a few years old. Are there any other alternatives out there now? Thanks very much!

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• why MVC instead of good old asp.net? Still not grasping why I should go this route??

  - by RJ

  I know this question has been asked before and I read all the answers but they still don't give me the answers I am looking for. I need something concrete. I volunteered to give a presentation on MVC to other developers in our group which forces me to learn it. The big question everyone has is: "What can MVC bring to the table that we can't do in asp.net or MVC can do faster. I have just gone through Nerd Dinner and actually created a complete website that sort of mimics Nerd Dinner. But as great a job that Scott Guthrie did on it, there are big gaps that aren't answered such as, how do I throw a textbox on the listing page with a button and do a simple search. In asp.net, I would throw a textbox, button and grid on the page and bind it to a sproc and away I go. What is the equivalent in MVC. I guess I need a really good tutorial on how to use MVC without using Linq-to-Sql. I know I am sort of babbling on about this but it is a very serious question that still seems to go unanswered. On a side note, the View page of MVC brings back nightmares of classic asp with all the in-line code that we got away from way back when with code behind pages. Yes, MVC has Controller and Model classes which are great but I still don't like the classic asp tags in the html. Help me out here, I really like the concept of MVC and want it to be successful but I need more!

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• How do I retrieve an automated report and save it to a database?

  - by Mason Wheeler

  I've got a web server that will take scripts in Python, PHP or Perl. I don't know much about any of those languages, but of the three, Python seems the least scary. It has a MySql database set up, and I know enough SQL to manage it and write queries for it. I also have a program that I want to add automated error reporting to. Something goes wrong, it sends a bug report to my server. What I don't know how to do is write a Python script that will sit on the web server and, when my program sends in a bug report, do the following: Receive the bug report. Parse it out into sections. Insert it into the database. Have the server send me an email. From what little I understand, this seems like it shouldn't be too difficult if I only knew what I was doing. Could someone point me to a site that explains the basic principles I'd need to create a script like this?

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• .Net Entity Framework & POCO ... querying full table problem

  - by Chris Klepeis

  I'm attempting to implement a repository pattern with my poco objects auto generated from my edmx. In my repository class, I have: IObjectSet<E> _objectSet; private IObjectSet<E> objectSet { get { if (_objectSet == null) { _objectSet = this._context.CreateObjectSet<E>(); } return _objectSet; } } public IQueryable<E> GetQuery(Func<E, bool> where) { return objectSet.Where(where).AsQueryable<E>(); } public IList<E> SelectAll(Func<E, bool> where) { return GetQuery(where).ToList(); } Where E is the one of my POCO classes. When I trace the database and run this: IList<Contact> c = contactRepository.SelectAll(r => r.emailAddress == "[email protected]"); It shows up in the sql trace as a select for everything in my Contact table. Where am I going wrong here? Is there a better way to do this? Does an objectset not lazy load... so it omitted the where clause? This is the article I read which said to use objectSet's... since with POCO, I do not have EntityObject's to pass into "E" http://devtalk.dk/CommentView,guid,b5d9cad2-e155-423b-b66f-7ec287c5cb06.aspx

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• .Net long-running scheduled code execution

  - by Prof Plum

  I am working on a couple of projects now where I really wish there was some sort of component that I could specify a time and date, and then execute some sort of method. DateTime date = new DateTime(x,x,x,x,x,x); ScheduledMethod sMethod = new ScheduledMethod(date, [method delegate of some sort]); \\at the specified date, sMethod invokes [method delegate of some sort] I know that I can do this with Windows Workflow Foundation as a long running process, which is good for certain things, but are there any alternatives? Workflow is not exactly straight forward with the details, and it would be nice to be able to deploy something more simple for light weight tasks. An example would be a method that checks a network folder once a day and deletes any files that are more than 30 days old. I realize that this may be pie in the sky dreaming, but this would be extremely useful for automating certain mundane maintinence tasks (scheduled sql operations, file system cleansing, routine email sending, etc.). It does not necessarily have to be .Net, but that is where I am coming from. Any ideas?

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• What can be used instead of Datatable in LINQ

  - by Kabi

  I have a SQL query that returns a Datatable: var routesTable = _dbhelper.Select("SELECT [RouteId],[UserId],[SourceName],[CreationTime] FROM [Routes] WHERE UserId=@UserId AND RouteId=@RouteId", inputParams); and then we can work with Datatable object of routesTable if (routesTable.Rows.Count == 1) { result = new Route(routeId) { Name = (string)routesTable.Rows[0]["SourceName"], Time = routesTable.Rows[0]["CreationTime"] is DBNull ? new DateTime() : Convert.ToDateTime(routesTable.Rows[0]["CreationTime"]) }; result.TrackPoints = GetTrackPointsForRoute(routeId); } I want to change this code to linq but I don't know how can I simulate Datatable in LINQ ,I wrote this part: Route result = null; aspnetdbDataContext aspdb = new aspnetdbDataContext(); var Result = from r in aspdb.RouteLinqs where r.UserId == userId && r.RouteId==routeId select r; .... but I don't know how can I change this part: if (routesTable.Rows.Count == 1) { result = new Route(routeId) { Name = (string)routesTable.Rows[0]["SourceName"], Time = routesTable.Rows[0]["CreationTime"] is DBNull ? new DateTime() : Convert.ToDateTime(routesTable.Rows[0]["CreationTime"]) }; would you please tell me how can I do this? EDIT here you can see the whole block of code in original public Route GetById(int routeId, Guid userId) { Route result = null; var inputParams = new Dictionary<string, object> { {"UserId", userId}, {"RouteId", routeId} }; var routesTable = _dbhelper.Select("SELECT [RouteId],[UserId],[SourceName],[CreationTime] FROM [Routes] WHERE UserId=@UserId AND RouteId=@RouteId", inputParams); if (routesTable.Rows.Count == 1) { result = new Route(routeId) { Name = (string)routesTable.Rows[0]["SourceName"], Time = routesTable.Rows[0]["CreationTime"] is DBNull ? new DateTime() : Convert.ToDateTime(routesTable.Rows[0]["CreationTime"]) }; result.TrackPoints = GetTrackPointsForRoute(routeId); } return result; }

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• Remove duplicate records/objects uniquely identified by multiple attributes

  - by keruilin

  I have a model called HeroStatus with the following attributes: id user_id recordable_type hero_type (can be NULL!) recordable_id created_at There are over 100 hero_statuses, and a user can have many hero_statuses, but can't have the same hero_status more than once. A user's hero_status is uniquely identified by the combination of recordable_type + hero_type + recordable_id. What I'm trying to say essentially is that there can't be a duplicate hero_status for a specific user. Unfortunately, I didn't have a validation in place to assure this, so I got some duplicate hero_statuses for users after I made some code changes. For example: user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2010-05-03 18:30:30' user_id = 18 recordable_type = 'Evil' hero_type = 'Halitosis' recordable_id = 1 created_at = '2009-03-03 15:30:00' user_id = 18 recordable_type = 'Good' hero_type = 'Hugs' recordable_id = 1 created_at = '2009-02-03 12:30:00' user_id = 18 recordable_type = 'Good' hero_type = NULL recordable_id = 2 created_at = '2009-012-03 08:30:00' (Last two are not a dups obviously. First two are.) So what I want to do is get rid of the duplicate hero_status. Which one? The one with the most-recent date. I have three questions: How do I remove the duplicates using a SQL-only approach? How do I remove the duplicates using a pure Ruby solution? Something similar to this: http://stackoverflow.com/questions/2790004/removing-duplicate-objects. How do I put a validation in place to prevent duplicate entries in the future?

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• Technology Plan - Which tools should I use?

  - by Armadillo

  Hi, Soon, I'll start my own software company. My primary product/solution will be a Billing/Invoice Software. In a near future, I pretend to expand this first module to an ERP. My app should be able to run as a stand-alone application and as a Web-based application (so there will be, probably two GUI for the same Database). My problem, now, is to choose the right tools; I'm talking about what programming language(s) should I use, what kind of database should I choose, and stuff like that. I'm primarily a VB6 programmer, so probably I'll choose the .net framework (vb/c#). But I'm seriously thinking about Java. Java has 2 "pros" that I really like: write once, run anywhere and it is free (I think...). I've been thinking about RIAs too, but I just don't have any substantial feedback about them... Then, I'll need a report tool. Crystal Reports? HTML based Reports? Other? Databases: I'm not sure if I should use SQL-Server Express or PostgreSQL (or other). I'd be happy to hear any comments and advices Thanks

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• Can't log in with a valid password using Authlogic and Ruby on Rails?

  - by kbighorse

  We support a bit of an unusual scheme. We don't require a password on User creation, and use password_resets to add a password to the user later, on demand. The problem is, once a password is created, the console indicates the password is valid: user.valid_password? 'test' = true but in my UserSessions controller, @user_session.save returns false using the same password. What am I not seeing? Kimball UPDATE: Providing more details, here is the output when saving the new password: Processing PasswordResetsController#update (for 127.0.0.1 at 2011-01-31 14:01:12) [PUT] Parameters: {"commit"="Update password", "action"="update", "_method"="put", "authenticity_token"="PQD4+eIREKBfHR3/fleWuQSEtZd7RIvl7khSYo5eXe0=", "id"="v3iWW5eD9P9frbEQDvxp", "controller"="password_resets", "user"={"password"="johnwayne"}} The applicable SQL is: UPDATE users SET updated_at = '2011-01-31 22:01:12', crypted_password = 'blah', perishable_token = 'blah', password_salt = 'blah', persistence_token = 'blah' WHERE id = 580 I don't see an error per se, @user_session.save just returns false, as if the password didn't match. I skip validating passwords in the User model: class User < ActiveRecord::Base acts_as_authentic do |c| c.validate_password_field = false end Here's the simplified controller code: def create logger.info("SAVED SESSION? #{@user_session.save}") end which outputs: Processing UserSessionsController#create (for 127.0.0.1 at 2011-01-31 14:16:59) [POST] Parameters: {"commit"="Login", "user_session"={"remember_me"="0", "password"="johnwayne", "email"="[email protected]"}, "action"="create", "authenticity_token"="PQD4+eIREKBfHR3/fleWuQSEtZd7RIvl7khSYo5eXe0=", "controller"="user_sessions"} User Columns (2.2ms) SHOW FIELDS FROM users User Load (3.7ms) SELECT * FROM users WHERE (users.email = '[email protected]') ORDER BY email ASC LIMIT 1 SAVED SESSION? false CACHE (0.0ms) SELECT * FROM users WHERE (users.email = '[email protected]') ORDER BY email ASC LIMIT 1 Redirected to http://localhost:3000/login Lastly, the console indicates that the new password is valid: $ u.valid_password? 'johnwayne' = true Would love to do it all in the console, is there a way to load UserSession controller and call methods directly? Kimball

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• P0ST variables to web server?

  - by OverTheRainbow

  Hello I've been trying several things from Google to POST data to a web server, but none of them work: I'm still stuck at how to convert the variables into the request, considering that the second variable is an SQL query so it has spaces. Does someone know the correct way to use a WebClient to POST data? I'd rather use WebClient because it requires less code than HttpWebRequest/HttpWebResponse. Here's what I tried so far: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim wc = New WebClient() 'convert data wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded") Dim postData = String.Format("db={0}&query={1}", _ HttpUtility.UrlEncode("books.sqlite"), _ HttpUtility.UrlEncode("SELECT id,title FROM boooks")) 'Dim bytArguments As Byte() = Encoding.ASCII.GetBytes("db=books.sqlite|query=SELECT * FROM books") 'POST query Dim bytRetData As Byte() = wc.UploadData("http://localhost:9999/get", "POST", postData) RichTextBox1.Text = Encoding.ASCII.GetString(bytRetData) Exit Sub Dim client = New WebClient() Dim nv As New Collection nv.Add("db", "books.sqlite") nv.Add("query", "SELECT id,title FROM books") Dim address As New Uri("http://localhost:9999/get") 'Dim bytRetData As Byte() = client.UploadValues(address, "POST", nv) RichTextBox1.Text = Encoding.ASCII.GetString(bytRetData) Exit Sub 'Dim wc As New WebClient() 'convert data wc.Headers.Add("Content-Type", "application/x-www-form-urlencoded") Dim bytArguments As Byte() = Encoding.ASCII.GetBytes("db=books.sqlite|query=SELECT * FROM books") 'POST query 'Dim bytRetData As Byte() = wc.UploadData("http://localhost:9999/get", "POST", bytArguments) RichTextBox1.Text = Encoding.ASCII.GetString(bytRetData) Exit Sub End Sub Thank you.

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• Visual Studio + Database Edition + CDC = Deploy Fail

  - by Ben

  Hi All, I've got a database using change data capture (CDC) that is created from a Visual Studio database project (GDR2). My problem is that I have a stored procedure that is analyzing the CDC information and then returning data. How is that a problem you ask? Well, the order of operation is as follows. Pre-deployment Script Tables Indexes, keys, etc. Procedures Post-deployment Script Inside the post-deployment script is where I enable CDC. Here-in lies the problem. The procedure that is acting on the CDC tables is bombing because they don't exist yet! I've tried to put the call to sys.sp_cdc_enable_table in the script that creates the table, but it doesn't like that. Error 102 TSD03070: This statement is not recognized in this context. C:...\Schema Objects\Schemas\dbo\Tables\Foo.table.sql 20 1 Foo Is there a better/built-in way to enable CDC such that it's references are available when the stored procedures are created? Is there a way to run a script after tables are created but before other objects are created? How about a way to create the procedure dependencies be damned? Or maybe I'm just doing things that shouldn't be done?!?! Now, I have a work around. Comment out the sproc body Deploy (CDC is created) Uncomment sproc Deploy Everything is great until the next time I update a CDC tracked table. Then I need to comment out the 'offending' procedure. Thanks for reading my question and thanks for your help!

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• Displaying windows-1252 text in a literal control

  - by GordonB

  I currently have an aspx page that has a placeholder on it. In the code-behind page i'm adding a literal control to the placeholder controls collection. The literal control just contains text/html read from a sql server database field. The only text character encoding i've used so far is UTF-8. I have the requirement for a specific page to use windows-1252 encoding. I've strapped this to the page, and browsers now recognise the proper encoding. <% Response.Charset= "windows-1252" %> My issue is that i have various german characters ( ö / ü / etc ) that aren't displaying correctly. As presumably they are still be written to the page in UTF-8 not in windows-1252. I'm looking at; Dim textEncoder = System.Text.Encoding.GetEncoding(1252) Which seems to be more geared up to dealing with byte arrays than text. Do i have to change my text to a byte array then encode as windows-1252 then get the text back out again, or is there a simpler way of achieving what i'm after?

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• Using Hibernate with MS ACCESS 2007 Database (Free JDBC Driver)

  - by Quentin T.

  1. I want to do a reverse engineering action with the Hibernate plugin of Eclipse on a MS Access 2007 Database. I'm forced to use a existing MS Access 2007 db. A easy solution is to buy the HXTT. But I want to use a free driver to do my work. So I tried to apply this post : http://www.programmingforfuture.com/2011/06/how-to-use-ms-access-with-hibernate.html (That uses the SQL Server dialect and the driver sun.jdbc.odbc.JdbcOdbcDriver) Unfortunately I have an error that nobody seems to have been on the internet: Exception while generating code Reason : org.hibernate.exception.GenericJDBCException: Error while reading primary key meta data for `c:/myaccessdb.mdb`.TableTest1 I have try to change the primary key on my MS Access DB (deleting all primary key) or to try the reverse engineering on a MS ACCESS with only one table without primary key, but I got all times the problems. 2. The purpose of my job is to transfer daily (weekly) an Oracle 11g database with data from an existing database MS ACCESS 2007. And I thought to use a procedure (Hibernate EJB) Java to be launched automatically every week to do the data transfer. Is this is the best solution ? Configuration : sun.jdbc.odbc.JdbcOdbcDriver v??? Hibernate v3.4 Eclipse ps: If you are a HXTT developer or seller please be indulgent with my post ;). Making money by making people believe that you help, it's bad ! A solution is to use Derby Client driver, as the solution in the post: Does anyone know if Hibernate and java will work effectively with Access? But a clarification of the answer of Rich Seller is required. Could you explain your answer and explain your configuration (hibernate.cfg.xml, persistence.xml and what URL you use in the property name="hibernate.connection.url") without using paying HXTT driver but with the free Derby driver.

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• Binding a null variable in a PreparedStatement

  - by Paul Tomblin

  I swear this used to work, but it's not in this case. I'm trying to match col1, col2 and col3, even if one or more of them is null. I know that in some languages I've had to resort to circumlocutions like ((? is null AND col1 is null) OR col1 = ?). Is that required here? PreparedStatement selStmt = getConn().prepareStatement( "SELECT * " + "FROM tbl1 " + "WHERE col1 = ? AND col2 = ? and col3 = ?"); try { int col = 1; setInt(selStmt, col++, col1); setInt(selStmt, col++, col2); setInt(selStmt, col++, col3); ResultSet rs = selStmt.executeQuery(); try { while (rs.next()) { // process row } } finally { rs.close(); } } finally { selStmt.close(); } // Does the equivalient of stmt.setInt(col, i) but preserves nullness. protected static void setInt(PreparedStatement stmt, int col, Integer i) throws SQLException { if (i == null) stmt.setNull(col, java.sql.Types.INTEGER); else stmt.setInt(col, i); }

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• Modelling deterministic and nondeterministic data separately

  - by Superstringcheese

  I'm working with the Microsoft ADO.NET Entity Framework for a game project. Following the advice of other posters on SO, I'm considering modelling deterministic and nondeterministic data separately. The idea for this came from a discussion on multiplayer games, but it seemed to make sense in a single-player scenario as well. Deterministic (things that aren't going to change during gameplay) Attributes (Strength, Agility, etc.) and their descriptions Skills and their descriptions and requirements Races, Factions, Equipment, etc. Base Attribute/Skill/Equipment loadouts for monsters Nondeterministic (things that will change a lot during gameplay) Beings' current AttributeModifers (Potion of Might = +10 Strength), current health and mana, etc. Player inventory, cash, experience, level Player quests states Player FactionRelationships ...and so on. My deterministic model would serve as a set of constants. My nondeterministic model would provide my on-the-fly operable data and would be serialized to a savegame file to maintain game state between play sessions. The data store will be an embedded SQL Compact database. So I might want to create relations between my Attributes table (deterministic model) and my BeingAttributeModifiers table (nondeterministic model), but how do I set that up across models? Det model/db Nondet model/db ____________ ________________________ |Attributes | |PlayerAttributeModifiers| |------------| |------------------------| |Id | |Id | |Name | |AttributeId | |Description | |SourceId | ------------ |Value | ------------------------ Should I use two separate models (edmx) that transact with a single database containing both deterministic-type and nondeterministic-type tables? Or should/can I use two separate databases in one model? Or two models each with their own database? With distinct models/dbs it seems like this will get really complicated and I'll end up fighting EF a lot, rolling my own transaction code, and generally losing out on a lot of the advantages of the framework. I know these are vague questions, I'm just looking for a sanity check before I forge ahead any further.

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• Extending URIs with 2 queries (i.e. 'viewauthorbooks.php?authorid=4' AND 'orderby=returndate") Possi

  - by Jess

  I have a link in my system as displayed above; 'viewauthorbooks.php?authorid=4' which works fine and generates a page displaying the books only associated with the particular author. However I am implementing another feature where the user can sort the columns (return date, book name etc) and I am using the ORDER BY SQL clause. I have this also working as required for other pages, which do not already have another query in the URI. But for this particular page there is already a paramter returned in the URL, and I am having difficulty in extending it. When the user clicks on the a table column title I'm getting an error, and the original author ID is being lost!! This is the URI link I am trying to use: <th><a href="viewauthorbooks.php?authorid=<?php echo $row['authorid']?>&orderby=returndate">Return Date</a></th> This is so that the data can be sorted in order of Return Date. When I run this; the author ID gets lost for some reason, also I want to know if I am using correct layout to have 2 parameters run in the address? Thanks.

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• Optimize LINQ Query for use with jQuery Autocomplete

  - by rockinthesixstring

  I'm working on building an HTTPHandler that will serve up plain text for use with jQuery Autocomplete. I have it working now except for when I insert the first bit of text it does not take me to the right portion of the alphabet. Example: If I enter Ne my drop down returns Nlabama Arkansas Notice the "N" from Ne and the "labama" from "Alabama" As I type the third character New, then the jQuery returns the "N" section of the results. My current code looks like this Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest ' the page contenttype is plain text' HttpContext.Current.Response.ContentType = "text/plain" ' store the querystring as a variable' Dim qs As Nullable(Of Integer) = Integer.TryParse(HttpContext.Current.Request.QueryString("ID"), Nothing) ' use the RegionsDataContext' Using RegionDC As New DAL.RegionsDataContext 'create a (q)uery variable' Dim q As Object ' if the querystring PID is not blank' ' then we want to return results based on the PID' If Not qs Is Nothing Then ' that fit within the Parent ID' q = (From r In RegionDC.bt_Regions _ Where r.PID = qs _ Select r.Region).ToArray ' now we loop through the array' ' and write out the ressults' For Each item In q HttpContext.Current.Response.Write(item & vbCrLf) Next End If End Using End Sub So where I'm at now is the fact that I stumbled on the "Part" portion of the Autocomplete method whereby I should only return information that is contained within the Part. My question is, how would I implement this concept into my HTTPHandler without doing a fresh SQLQuery on every character change? IE: I do the SQL Query on the QueryString("ID"), and then on every subsequent load of the same ID, we just filter down the "Part". http://www.example.com/ReturnRegions.axd?ID=[someID]&Part=[string]

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• Webmethod on my C# (server side) doesn't return data to client side (javascript)

  - by Philo

  I am using a c# Webmethod to return results to my client side written in Javascript. [WebMethod] public static string MyMethod(string Id) { SQL QUERIES and then .... // adding data to member class. Member member = new Member(Name, DOB, Sex, Member_Identification, Dates_of_services); return JsonConvert.SerializeObject(member); <-- member is a class of List strings } And on the client side you could invoke this method using the jQuery.ajax() function like this: $.ajax({ url: 'default.aspx/MyMethod', type: 'POST', contentType: 'application/json; charset=utf-8', data: JSON.stringify({ ID : ID }), success: on success { } }); function onSuccess(data) { // parses json returned data var jsondata = $.parseJSON(data.d); ..... } Now the data returned to the client side are Lists of Strings. This method works for me most times. However for one or two queries, the method runs forever without returning to the client side. On the server side however, I can use breakpoints and see that all the Lists of strings have been formed correctly. But I cannot seem to find out why they are never returned to the client side. My code reaches till the return statement on the server side and then the program just runs forever. It never reaches the function 'onsuccess' Can anyone tell me why this can happen? Anomalies in data maybe?

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• At which line in the following code should I commit my unit of work?

  - by Pure.Krome

  I have the following code which is in a transaction. I'm not sure where/when I should be commiting my unit of work. On purpose, I've not mentioned what type of Respoistory i'm using - eg. Linq-To-Sql, Entity Framework 4, NHibernate, etc. If someone knows where, can they please explain WHY they have said, where? (i'm trying to understand the pattern through example(s), as opposed to just getting my code to work). Here's what i've got :- using ( TransactionScope transactionScope = new TransactionScope ( TransactionScopeOption.RequiresNew, new TransactionOptions { IsolationLevel = IsolationLevel.ReadUncommitted } ) ) { _logEntryRepository.InsertOrUpdate(logEntry); //_unitOfWork.Commit(); // Here, commit #1 ? // Now, if this log entry was a NewConnection or an LostConnection, // then we need to make sure we update the ConnectedClients. if (logEntry.EventType == EventType.NewConnection) { _connectedClientRepository.Insert( new ConnectedClient { LogEntryId = logEntry.LogEntryId }); //_unitOfWork.Commit(); // Here, commit #2 ? } // A (PB) BanKick does _NOT_ register a lost connection, // so we need to make sure we handle those scenario's as a LostConnection. if (logEntry.EventType == EventType.LostConnection || logEntry.EventType == EventType.BanKick) { _connectedClientRepository.Delete( logEntry.ClientName, logEntry.ClientIpAndPort); //_unitOfWork.Commit(); // Here, commit #3 ? } _unitOfWork.Commit(); // Here, commit #4 ? transactionScope.Complete(); }

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• Google app engine: Poor Performance with JDO + Datastore

  - by Bosh

  I have a simple data model that includes USERS: store basic information (key, name, phone # etc) RELATIONS: describe, e.g. a friendship between two users (supplying a relationship_type + two user keys) I'm getting very poor performance, for instance, if I try to print the first names of all of a user's friends. Say the user has 500 friends: I can fetch the list of friend user_ids very easily in a single query. But then, to pull out first names, I have to do 500 back-and-forth trips to the Datastore, each of which seems to take on the order of 30 ms. If this were SQL, I'd just do a JOIN and get the answer out fast. I understand there are rudimentary facilities for performing joins across un-owned relations in a relaxed implementation of JDO (as described at http://gae-java-persistence.blogspot.com) but they sound experimental and non-standard (e.g. my code won't work in any other JDO implementation). Is this really my best bet? Otherwise, how do people extract satisfactory performance from JDO/Datastore in this kind of (very common) situation? -Bosh

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• Reading/Writing DataTables to and from an OleDb Database LINQ

  - by jsmith

  My current project is to take information from an OleDbDatabase and .CSV files and place it all into a larger OleDbDatabase. I have currently read in all the information I need from both .CSV files, and the OleDbDatabase into DataTables.... Where it is getting hairy is writing all of the information back to another OleDbDatabase. Right now my current method is to do something like this: OleDbTransaction myTransaction = null; try { OleDbConnection conn = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + Database); conn.Open(); OleDbCommand command = conn.CreateCommand(); string strSQL; command.Transaction = myTransaction; strSQL = "Insert into TABLE " + "(FirstName, LastName) values ('" + FirstName + "', '" + LastName + "')"; command.CommandType = CommandType.Text; command.CommandText = strSQL; command.ExecuteNonQuery(); conn.close(); catch (Exception) { // IF invalid data is entered, rolls back the database myTransaction.Rollback(); } Of course, this is very basic and I'm using an SQL command to commit my transactions to a connection. My problem is I could do this, but I have about 200 fields that need inserted over several tables. I'm willing to do the leg work if that's the only way to go. But I feel like there is an easier method. Is there anything in LINQ that could help me out with this?

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• how to check null value of Integer type field in ASP.NET MVC view?

  - by Vikas

  Hi, I have integer type field in database which is having property "Not Null". when i create a view & do a validation, if i left that field blank, it will consider it as 0 so i can not compare it with 0 because if someone insert a value 0 then it will be considered as error! one another problem is that i am using Model error as described in the book "ASP.NET MVC 1.0" @ Scott Gu blog. And I am checking the value in partial class of object (created by LINQ-To-SQL). i.e public partial class Person { public bool IsValid { get { return (GetRuleViolations().Count() == 0); } } public IEnumerable<RuleViolation> GetRuleViolations() { if (String.IsNullOrEmpty(Name)) yield return new RuleViolation("Name is Required", "Name"); if (Age == 0) yield return new RuleViolation("Age is Required", "Age"); yield break; } partial void OnValidate(ChangeAction action) { if (!IsValid) throw new ApplicationException("Rule violations prevent saving"); } } There is also problem with range. Like in database if i declared as smallint i.e. short in c#, now if i exceed that range then it gives error as "A Value is reguired". so finally is there any best way for validation in ASP.NET MVC?

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• Moving information between databases

  - by williamjones

  I'm on Postgres, and have two databases on the same machine, and I'd like to move some data from database Source to database Dest. Database Source: Table User has a primary key Table Comments has a primary key Table UserComments is a join table with two foreign keys for User and Comments Dest looks just like Source in structure, but already has information in User and Comments tables that needs to be retained. I'm thinking I'll probably have to do this in a few steps. Step 1, I would dump Source using the Postgres Copy command. Step 2, In Dest I would add a temporary second_key column to both User and Comments, and a new SecondUserComments join table. Step 3, I would import the dumped file into Dest using Copy again, with the keys input into the second_key columns. Step 4, I would add rows to UserComments in Dest based on the contents of SecondUserComments, only using the real primary keys this time. Could this be done with a SQL command or would I need a script? Step 5, delete the SecondUserComments table and remove the second_key columns. Does this sound like the best way to do this, or is there a better way I'm overlooking?

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• Understanding Wordpress database schema - querying from 3rd party app

  - by deceze

  Is there an easy way to grab the latest posts out of a Wordpress wp_posts table using a simple SQL query? I have a Wordpress 2.9.2 installation as part of, but separate from, a larger system. It has a customized theme to look like the rest of the site but has otherwise nothing to do with it. I want to display the latest handful of headlines of posts made using Wordpress on a site of that other system. Preferably I do not want to mess around with importing any of the Wordpress library files. Looking at the database structure I can't see an easy, straight-forward query to simply get the latest revision of the latest posts. The post_status can either be "post" or "inherit", the post_type "post" or "revision" and the parent "0" or the id of the original post of a revision. I can't figure out how to reliably filter different revisions of the same post, drafts, attachments and pages out of this mess and just get the latest revision of the latest posts. I'm aware that the database schema is subject to change in subsequent versions of Wordpress, so shouldn't be relied upon, but that's a minor concern, since it's such a minor feature that could easily be fixed. If I understood how that database is supposed to work, that is.

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• Why is my django bulk database population so slow and frequently failing?

  - by bryn

  I decided I'd like to use django's model system rather than coding raw SQL to interface with my database, but I am having a problem that surely is avoidable. My models.py contains: class Student(models.Model): student_id = models.IntegerField(unique = True) form = models.CharField(max_length = 10) preferred = models.CharField(max_length = 70) surname = models.CharField(max_length = 70) and I'm populating it by looping through a list as follows: from models import Student for id, frm, pref, sname in large_list_of_data: s = Student(student_id = id, form = frm, preferred = pref, surname = sname) s.save() I don't really want to be saving this to the database each time but I don't know another way to get django to not forget about it (I'd rather add all the rows and then do a single commit). There are two problems with the code as it stands. It's slow -- about 20 students get updated each second. It doesn't even make it through large_list_of_data, instead throwing a DatabaseError saying "unable to open database file". (Possibly because I'm using sqlite3.) My question is: How can I stop these two things from happening? I'm guessing that the root of both problems is that I've got the s.save() but I don't see a way of easily batching the students up and then saving them in one commit to the database.

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