Entity Framework Query Filter

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.

Can you post example of what and how exactly you want to achieve this? — Akash Kava
– Akash Kava, Commented Aug 30, 2011 at 12:28

Ladislav Mrnka · Accepted Answer · 2011-08-30 12:31:25Z

2

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;
        }
    }  
}

edited Aug 30, 2011 at 12:31

answered Aug 30, 2011 at 12:26

Ladislav Mrnka

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2 Comments

BowlingForGreens Over a year ago

So the combination of EF and RIA Services has nothing resembling the QueryInterceptors in WCF Data Services?

Ladislav Mrnka Over a year ago

I'm not sure about RIA services but EF itself doesn't have any such functionality. QueryInterceptors are specific to WCF Data Services.

Jim Wooley · Accepted Answer · 2011-08-30 15:19:06Z

1

Are you trying to do something like only show the active Customers? If so, you can use Inheritance and create an ActiveCustomer type and add a condition in your mapping to Status == "Active". Then set your Customer type as an Abstract Base Class to prevent direct instantiation. You can then query your model for Customers.OfType<ActiveCustomer>().

answered Aug 30, 2011 at 15:19

Jim Wooley

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