Entity Framework Code First and Multiple Assemblies

Question

I have a subclass in a different assembly to its base class. The parent is a POCO class used for EF Code First.

When I try to add an instance of inherited class to the database I get InvalidOperationException: "Object mapping could not be found for Type with identity 'Foo.Bar.MyInheritedClass'".

It works fine if subclass is in same assembly as base class.

In regular EF the solution seems to be a call to ObjectContext.MetadataWorkspace.LoadFromAssembly(assembly). But I can't figure out how this relates to Code First.

Any advice?

I'm using Entity Framework 4.1 RC.

Why can't you still call that function? I've not actuaqlly checked, but based on some quick searching you should be able to access the MetadataWorkspace from your DbContext using dbContext.MetadatWorkspace. Does that not work? — Kevin Cathcart
– Kevin Cathcart, Commented Mar 21, 2011 at 14:59
Yes, you can cast DbContext to IObjectContextAdapter and retrieve it's underlying ObjectContext (See: weblogs.asp.net/jgalloway/archive/2011/01/21/…). — David Russell
– David Russell, Commented Mar 23, 2011 at 10:01
That allowed me to try MetadataWorkspace.LoadFromAssembly() but it didn't fix my problem :( — David Russell
– David Russell, Commented Mar 23, 2011 at 10:01

David Russell · Accepted Answer · 2011-03-23 13:18:00Z

3

I solved this by inheriting from the first assembliy's DbContext, adding a DbSet<> for the derived class, and then adding new instances of derived type to to that.

Posted code on MSDN forum here.

answered Mar 23, 2011 at 13:18

David Russell

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Scott Stafford · Accepted Answer · 2013-01-28 20:50:42Z

2

I know this post is a bit old, but I was able to accomplish this using @Dave's recomendation inside the constructor:

public Context() {
    ((IObjectContextAdapter)this).ObjectContext.MetadataWorkspace.LoadFromAssembly(
        System.Reflection.Assembly.GetAssembly(
             typeof(--[Inherited DbContext]--)));
}

edited Jan 28, 2013 at 20:50

Scott Stafford

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answered Jun 13, 2011 at 15:21

kroehre

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Comments

Tariqulazam · Accepted Answer · 2012-10-05 02:30:03Z

1

I'm quite new to EF (Entity Framework 4) and I got the same exception when I made changes in the model.

My problem turned out to be that I did not know EF need all the names on all the navigation properties to agree, not only their type. For example if there is a navigation property named foo, then there needs to be a declared variable in the corresponding class with the very same name.

edited Oct 5, 2012 at 2:30

Tariqulazam

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answered Oct 4, 2012 at 7:04

John

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