Silverlight - LinqToEntities - How Do I Return Anonymous Types

I'm not sure if I'm going at this the right way. I have a Silverlight app and using Entity Framework for a lot of it. I have Two Entities mapped to my database: Header and Details. I want to submit a left outter join to get all headers and details counts - even if the header record has no detail record. Here is the Linq Query I want to run from the Client:

var query =
      from head in storeContext.Headers
      join detail in storeContext.Details
      on head.HeadId equals details.HeadId
      into group
      select new 
      {
        Desc = head.Description,
        MyCount = group.Count()
      };

Since this is Silverlight, I need to build my query, then submit it to the server with the storeContext.Load<T>() method from my Domain Service (Context on the client). Because this method is expecting a type, I don't know how to structure the call to return an anonymous type as I am dong above?

Am I doing 开发者_开发百科this all wrong? Should I be using an Invoke method for something like this? If so, how and where do I define the type I want to return?

Is someone could point me in the right direction I would really appriciate it.

Thanks... Scott

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You can't return an anonymous type. They are, by necessity, local to the current scope.

Your query looks correct, but you will need to return a named type:

var query =
      from head in storeContext.Headers
      join detail in storeContext.Details
      on head.HeadId equals details.HeadId
      into group
      select new MyHelper // SPECIFY A CLASS HERE
      {
        Desc = head.Description,
        MyCount = group.Count()
      };

Your query method will need to return an IEnumerable<MyHelper>:

public IEnumerable<MyHelper> GetInfo()
{
    var query ...

    return query;
}

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You can never return a value that is an instance of an anonymous type from a method. Anonymous types are always local to the method. If you want to return a type over WCF you're going to have to write the class yourself, rather than relying on anonymous types.