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re: LINQ to SQL : Start with a good foundation by defining a custom DataContext

Webys — Thu, 03 Jul 2008 11:59:01 GMT

I have a little problem I'm a beginner in LINQ to SQL and I've follow the tutorial from ScottGu's blog: weblogs.asp.net/.../linq-to-sql-part-5-binding-ui-using-the-asp-linqdatasource-control.aspx

All was ok I use VS 2008 (I've converted from VB.NET to C# , I use C#) but when I wish to put the code from App_Code in an sub dir like DAL or BLL (for extensibility of entities like products with partial clases) and generate again the dblm file I've receiving en error:

1. first in my BLL dir from App_Code:

public partial class Product

{

partial void OnValidate(System.Data.Linq.ChangeAction action)

{

if (action == ChangeAction.Update && this.Discontinued == true && this.UnitsOnOrder > 0)

{

throw new ArgumentException("Record level can't be grather than 0 if Product is Discontinued");

}

and I've included the namespace : using DAL;

... but still error message is :No defining declaration found for implementing declaration of partial method 'Product.OnValidate(System.Data.Linq.ChangeAction)'

2 If i comment all BLL code from my extensibility partial class Product I receive an general error:

Could not load type 'NorthwindDataContext'.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Could not load type 'NorthwindDataContext'.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[HttpException (0x80004005): Could not load type 'NorthwindDataContext'.]

System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) +565

System.Web.UI.WebControls.LinqDataSourceView.get_ContextType() +68

[InvalidOperationException: Could not find the type specified in the ContextTypeName property of LinqDataSource 'CategoryLinqDS'.]

System.Web.UI.WebControls.LinqDataSourceView.get_ContextType() +193

System.Web.UI.WebControls.LinqDataSourceView.CreateContextAndTable() +458

System.Web.UI.WebControls.LinqDataSourceView.EnsureContextAndTable(Boolean selecting) +39

System.Web.UI.WebControls.LinqDataSourceView.ExecuteSelect(DataSourceSelectArguments arguments) +421

System.Web.UI.WebControls.ListControl.OnDataBinding(EventArgs e) +92

System.Web.UI.WebControls.ListControl.PerformSelect() +31

System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +70

System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +82

System.Web.UI.WebControls.ListControl.OnPreRender(EventArgs e) +26

System.Web.UI.Control.PreRenderRecursiveInternal() +86

System.Web.UI.Control.PreRenderRecursiveInternal() +170

System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2041

--------------------------------------------------------------------------------

Version Information: Microsoft .NET Framework Version:2.0.50727.1433; ASP.NET Version:2.0.50727.1433

Thanks in advance guys. :)

re: LINQ to SQL : Start with a good foundation by defining a custom DataContext

Nick Hauenstein — Wed, 04 Jun 2008 16:18:28 GMT

@Alan:

Linq is in System.Core

re: LINQ to SQL : Handling disconnected CRUD operations in ASP.Net

Thomas Jespersen — Wed, 28 May 2008 17:42:35 GMT

You don't have to work with disconnected objectes i ASP.NET. When the user posts back changes, then the first thing you do is to featch the latest version of the object form the database (using the id, from the viewstate).

Then you verify that the timestamp of the fetched object equals the time stamp from your viewstate. If they do, you are set to go. If they don't you can trhow an exception right there, because you know that the update will fail.

While theis requires an extra roundtrip to the server, this can be a very good aproch if you entity object is more complex. E.g. its an Aggregate which contains other objectes. Also by using this aproach you don't have to send every property to the client, which saves you from checking that the data has not been tampered with (say a usere changes the customer id of an order... how would you detect that)?

: Thomas

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Miguel Domingos — Thu, 29 Nov 2007 13:43:01 GMT

I also ran into another issue:

Change the linq mtehod "ModifiedEntities" to "Inserts"

VS 2008 Beta 2 to RTM « Tales from a Trading Desk

VS 2008 Beta 2 to RTM « Tales from a Trading Desk — Wed, 28 Nov 2007 00:16:46 GMT

Pingback from VS 2008 Beta 2 to RTM « Tales from a Trading Desk

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Kevin Fitzgerald — Tue, 27 Nov 2007 20:42:43 GMT

Managed to get through all the changes, still have to wonder about the name change from Add to InsertOnSubmit. More wordy yes but explicit, in that case I would expect to see Insert (without submit)?

I liked the way (since the May 2006 CTP) that I got a collection (ok then an EntitySet) from the designer. Made a lot of sense to Add and Remove from that collection, but the InsertOnSubmit kinda ruins is for me...

Bah humbug!

Kev

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Peter Kassenaar — Fri, 23 Nov 2007 10:31:52 GMT

Thanks for sharing! Very valuable stuff.

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Rocky Moore — Wed, 21 Nov 2007 22:23:24 GMT

One other possible issue I have ran into is the ListView change. I found info on it at:

www.danielmoth.com/.../item-placeholder-must-be-specified-on.html

Updating VS 2008 B2 Websites to RTM

TheCoder — Wed, 21 Nov 2007 21:12:34 GMT

Updating VS 2008 B2 Websites to RTM

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Rocky Moore — Wed, 21 Nov 2007 21:01:23 GMT

Thanks for the tips! In the process of doing a few sites. Sure wish they would have left the Add and Remove alone, it seemed less "database"ish and more "collection"ish with Add and Remove. Oh well.. On to the trenches!

Write Less, Do More, But Keep It Simple - All Comments

re: LINQ to SQL : Start with a good foundation by defining a custom DataContext

re: LINQ to SQL : Start with a good foundation by defining a custom DataContext

re: LINQ to SQL : Handling disconnected CRUD operations in ASP.Net

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

VS 2008 Beta 2 to RTM « Tales from a Trading Desk

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Updating VS 2008 B2 Websites to RTM

re: Converting web site projects from Visual Studio 2008 Beta 2 to Visual Studio 2008 RTM

Write Less, Do More,
But Keep It Simple - All Comments