Question

Is it possible to add a sort-of a global filter to an Entity Framework object context? Such as having an ObjectMaterialized which can return an indicator of whether or not to include a given object in the result set.

Answer 1

No it is not possible. Entity framework and its built in providers don’t have any support for global filters.

You can achieve some basic filtering with simple wrapper:

public class MyContext : ObjectContext
{
    private ObjectSet<MyEntity> myEntities;

    public Expression<Func<MyEntity, bool>> GlobalMyEntityFilter { get; set; }

    public IQueryable<MyEntity> MyEntities
    {
        get
        {
            if (GlobalMyEntityFilter != null)
            {
                return myEntities.Where(GlobalMyEntityFilter);
            }

            return myEntities;
        }
    }  
}