Making entity framework treat views with many-to-many relationships, like it does tables with many-to-many relationships

I have three views that I've manually created in the DB.

First view is "Region", the second is "FIPS" and the last is a many-to-many between them called "Region2FIPS". These are all views, and I only need read access the data, so I'm not worried about having updateable views.

I have added each of these views to Entity Framework, and created the approp开发者_StackOverflow中文版riate associations between them.

Region to Region2FIPS is a 1 to many. FIPS to Region2FIPS is a 1 to many.

The "Region2FIPS" view contains only two columns, one called "FIPSID" the other "RegionID". These column are associated with their respective views in the relationships I defined above.

When this type of association is made on tables in the DB, Entity Framework knows that it is a many-to-many relationship and it creates a navigation property on "Region" called "FIPS" that I can use to navigate through the child collection of FIPS. It does likewise for "FIPS" to "Region".

However, when done manually, with views, it does not exhibit that behavior. Instead, my "Region" object has a collection of "Region2FIPS" objects, which each have a navigation property called "FIPS" which is of type "FIPS". And my "FIPS" object has a collection of "Region2FIPS" objects, which each have a navigation property called "Regions" of type "Region".

I assume this has something to do with the fact that I can't create foreign key references on the views, so entity framework doesn't realize the many-to-many relationship. But I thought that if I manually created the many-to-many relationship between the views it would recognize it and properly handle the navigation between the types. Is there a way for me to force it to do this?

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It's possible, but the designer doesn't really help you here. You have to do the mapping manually.

One fairly easy way is to use Code First mapping. But this means your model has to be Code First to begin with. If you're writing a new model, just do that.

If you're using DB First mapping, however, you will have to do the mapping manually. Your SSDL will probably already be correct, once you define the "primary keys" of the views. You would then have to remove the "Region2FIPS" objects from the CSDL (not just from the designer!) and manually patch up the MSL.

Perhaps the easiest way to do this would be to use the designer to automatically map real DB tables (not views) with a similar schema and then replace the table names with view names in the EDMX, using the XML editor.