Using ObjectQuery with Entity Framework

Normally we manipulate the Entity Framework using var like the statements below.


BeancurdModel.BeancurdEntities context = new BeancurdModel.BeancurdEntities();
var bc = from b in context.Beancurds select b;


We can actually do it without using var. The below statements are using ObjectQuery<T>.


string queryString =

            @”SELECT VALUE product FROM AdventureworksEntities.Products AS product”;


// Call the constructor with the specified query and the ObjectContext.

ObjectQuery<Product> productQuery2 =

    newObjectQuery<Product>(queryString, context);


I have put the following 2 MSDN articles into a sample.


1.     ObjectQuery<T> Class


2.     ObjectQuery<T>.GroupBy Method


Download the sample project from sample file name is ConAppObjectQuery.rar. My MSN ID is


Resources :

Using IEnumerable with LINQ

How to pass var as parameter

Get data from parent-child relationship using edmx

Enumerable.Cast<TResult> Method


About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress ( till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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3 Responses to Using ObjectQuery with Entity Framework

  1. Filip Cotan says:

    Nice! But I have a problem with that “context” parameter.
    This is my code:
    string connectionString = “theConnectionString”;
    ObjectContext context = new ObjectContext(connectionString);

    In the connectionString string , I have , obviously, the Data Source. And I get this error:
    “Keyword not supporterd ‘Data Source ….’ . Can you help me?

    • chanmingman says:

      I need to see the connection string.

      • Filip Cotan says:

        I fiexd that bug using IObjectContextAdapter interface . This is my code:
        var objectContext = ((IObjectContextAdapter)myDbContextObject).ObjectContext;

        and I passed it in the ObjectQuery constructor:
        ObjectQuery objQuery = new ObjectQuery(connString, objectContext);
        and it’s work … Thank for help anyway🙂

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