Extending SQL LINQ Table Class

[Mark Olbert]

I am trying to extend a table entity class (generated from the visual designer for data contexts) with a property that has no
corresponding column in the underlying Sql Server table.

When I do this, I get a NotSupportedException complaining that the property I added has no supported translation to the database.

The documentation implies that properties not marked with the Column attribute will be ignored when interfacing to the
database...but that's not what appears to be happening.

Is there some other attribute I need to decorate the property with to have the property "skipped"? Or is it just not possible to add
properties to table entity classes using partial classes? If that's the case, the documentation should make that clear.

- Mark

 

[Steven Cheng[MSFT]]

Hi Mark,

I think custom properites with partial class for LINQ object class is
supported. As for the property you added, did you by any chance used it in
any data query expression? It seems the custom property will not be
recognized in any query expression to the datasource. Or you just get the
compile error without using the property in any place? here is a web forum
thread mentioned something about add custom property:

#Custom properties in LINQ to SQL classes
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=1656614&SiteID=1

and here is a blog article about extending LINQ to SQL query:

#LINQ to SQL (Part 8 - Executing Custom SQL Expressions)
http://weblogs.asp.net/scottgu/archive/2007/08/27/linq-to-sql-part-8-executi
ng-custom-sql-expressions.aspx

Hope this helps.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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

From: Mark Olbert <[email protected]>
Newsgroups: microsoft.public.dotnet.framework
Subject: Extending SQL LINQ Table Class
Date: Sun, 06 Jan 2008 17:37:00 -0800

I am trying to extend a table entity class (generated from the visual

designer for data contexts) with a property that has no

corresponding column in the underlying Sql Server table.

When I do this, I get a NotSupportedException complaining that the

property I added has no supported translation to the database.

The documentation implies that properties not marked with the Column

attribute will be ignored when interfacing to the

database...but that's not what appears to be happening.

Is there some other attribute I need to decorate the property with to have

the property "skipped"? Or is it just not possible to add

properties to table entity classes using partial classes? If that's the

case, the documentation should make that clear.

 

[Mark Olbert]

Steven,

Thanks for the quick reply. You're right, extended properties work fine so long as you don't try to use them in a query.

I think I saw some references on the web to replacing properties that don't map to database fields to method calls which can be used
in queries.

BTW, the second link you gave me doesn't work.

- Mark

 

[Steven Cheng[MSFT]]

Thanks for your reply Mark,

Do you mean the "LINQ to SQL (Part 8 - Executing Custom SQL Expressions) "
link was broken? If so, you can try searching the subject in web directly.
There are a series of LINQ to SQL articles on ScottGu's blog. They are very
helpful.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


This posting is provided "AS IS" with no warranties, and confers no rights.

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

From: Mark Olbert <[email protected]>
Newsgroups: microsoft.public.dotnet.framework
Subject: Re: Extending SQL LINQ Table Class
Date: Mon, 07 Jan 2008 10:33:00 -0800

Steven,

Thanks for the quick reply. You're right, extended properties work fine so

long as you don't try to use them in a query.

I think I saw some references on the web to replacing properties that

don't map to database fields to method calls which can be used

in queries.

BTW, the second link you gave me doesn't work.

- Mark