Entity Framework and repository pattern problem

Question

I am using generic repository pattern with methods:

    private ObjectQuery<T> ObjectQueryList()
    {
        var list = CamelTrapEntities.CreateQuery<T>(EntitySetName);
        return list;
    }

    public IQueryable<T> List()
    {
        return ObjectQueryList();
    }

Metod List() returns IQueryable<T>, becase IQueryable<T> is easy to mock. I also have extension method:

    public static IQueryable<T> Include<T>(this IQueryable<T> obj, string path)
    {
        if (obj is ObjectQuery<T>)
            (obj as ObjectQuery<T>).Include(path);

        return obj;
    }

This method is used outside of repository to get entity list with navigation properties already loaded, for example: List.Include("CreatedBy"). The problem is that it doesn't work. All includes are ignored. when I change List() method to

    public ObjectQuery<T> List()
    {
        return ObjectQueryList();
    }

everything works fine.

How should I implement repository pattern to be able to execute more complex queries?

LukLed LukLed · Accepted Answer · 2009-09-29T21:16:11

Reflector gave me an answer:

public ObjectQuery<T> Include(string path)
{
    EntityUtil.CheckStringArgument(path, "path");
    return new ObjectQuery<T>(base.QueryState.Include<T>((ObjectQuery<T>) this, path));
}

Include returns new ObjectQuery object and my Include function returned old object. Changing to

public static IQueryable<T> Include<T>(this IQueryable<T> obj, string path)
{
    if (obj is ObjectQuery<T>)
        return (obj as ObjectQuery<T>).Include(path);

    return obj;
}

solved the problem. Few hours lost and I hate Entity Framework more:)

It made me also realise that I should create another List function with Include parameter and not allow doing includes outside repository.

Entity Framework and repository pattern problem

3 Answers