Using Custom POCO Code with Code First in Entity Framework 4.3?
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I have an existing database that I cannot change, but want to access using EF.  For 90% of the database, I have been able to get Code First EF to work, and I am very impressed.  

In one case, there is a table that is like this:

Table Dog has a foreign Key (typeId) into table DogType.

The table DogType has a composite primary key , which consists of typeId and another id, which represents something that is configured into the program.

So, to find a particular dog type, you have to have a typeId and another piece of information which
is related to program configuration.  

I'd like to use a "Navigation" Property that returns a dog type, but don't think I can configure this in code first.
Consequently, I'd like to specify that when the navigation property getter is called, it should use a query that can get the appropriate dog type and return it appropriately.  

However, I don't want to dirty my POCO with the Context calls to return the result of the query. In other words, I'd like to have a method on Dog - Type Dog.GetType(), that does not have something like context.Types.Where(...) in it.

Ideally, it would work like the Navigation collections do, where EF does it's magic and returns the appropriate results.

Intuitively, it seems like I should be able to either configure this using POCO-like code or use/extend a proxy to extend the configuration to use the particular query I want when the accessor is called.

Is this possible? 