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In my database schema each forum has a category and categories can have many forums. I'm trying to list categories and their respective forums with the following code: 

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<dynamic>" %>

<asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">
    Index
</asp:Content>

<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">

    <h2>Index</h2>
    <% foreach (GameSite.Models.Category category in (IEnumerable)ViewData["Categories"])
       { %>
       <%= category.Name %>
       <% foreach (GameSite.Models.Forum forum in (IEnumerable)category.Forums)
          { %>
          <%= forum.Name %>
       <% } %>
    <% } %>
</asp:Content>

When this is run I get the following error:

Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. 

Compiler Error Message: CS0012: The type 'System.Data.Linq.EntitySet`1<T0>' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

Source Error:    
Line 11:        { %>
Line 12:        <%= category.Name %>
Line 13:        <% foreach (GameSite.Models.Forum forum in (IEnumerable)category.Forums)
Line 14:           { %>
Line 15:           <%= forum.Name %>

I can confirm that System.Data.Linq is being referenced in my project.

Any ideas?

Matthew H
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    Are you sure you are referencing the 4.0 of System.Data.Linq version rather than the 3.5 version? Did you check the web.config file? – Tom Cabanski Apr 15 '10 at 01:37
  • Yes, I'm referencing the 4.0 version. What do you want me to look for in the web.config file? I don't see System.Data.Linq mentioned anywhere. – Matthew H Apr 15 '10 at 01:39

1 Answers1

43

Adding this to the web.config file did the trick.

    <add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
Matthew H
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    What part of the web.config file do I need to add this? – beaudetious Jan 27 '11 at 19:48
  • I've forgotten now, so maybe someone else can help you more. Only advice I can offer is to look for other lines and chuck it in there. – Matthew H Feb 04 '11 at 21:49
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    ` ` – Austin May 16 '11 at 15:35
  • I'm having the same problem. In MVC 4, you don't need to add the assemblies, and it actually throws an error when you try to do so. I'm getting this error on only one page. All my other pages are using LINQ with no problems. – shubniggurath Mar 26 '13 at 12:33
  • Clicking on the reference and setting `copy local= true` fixed it for me. It was breaking in the Views, in the controllers it worked find. Very strange. MVC4 - I also added the namesapce into the views web.config – Piotr Kula Apr 14 '14 at 21:10