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POEntity Framework POCO with Foreign keys
 

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    <p>My question can better be explained via example code. I am using POCO with change tracking proxies that is generated by the C# POCO generator by default. Please see below.</p> <p>Assume you have Movie, MusicDirector and Director in the database and the relationship between them is a Director &amp; MusicDirector can direct multiple movies and a movie can have only one Director and MusicDirector. Since I am a new user and cannot post images, here is my db structure. </p> <p>Movie table has MovieId, Name,MusicDirectorId,DirectorId</p> <p>Director table has DirectorId, Name</p> <p>MusicDirector table has MusicDirectorId, Name </p> <p>Here is the link to the diagram. <a href="http://i.stack.imgur.com/ce49r.png" rel="nofollow">http://i.stack.imgur.com/ce49r.png</a>.</p> <p>I am trying to insert a new movie and the director and musicdirector "already exists" in the db. Below is my code. </p> <pre><code>Movie movie = new Movie(); movie.Name = "Movie1"; movie.Director = new Director() { Name = "DirectorA" }; movie.MusicDirector = new MusicDirector() { Name = "MusicDirectorA" }; using (TestEFEntities ctx = new TestEFEntities()) { movie.Director = ctx.Directors.Where(x =&gt; x.Name == movie.Director.Name).FirstOrDefault(); movie.MusicDirector = ctx.MusicDirectors.Where(x =&gt; x.Name == movie.MusicDirector.Name).FirstOrDefault(); ctx.Movies.AddObject(movie); ctx.SaveChanges(); } </code></pre> <p>Now when I do this, MusicDirector record is added again even though it is overwritten by the record from the db. You may think why I am keeping this line movie.Director = new Director() { Name = "DirectorA" }; initially, it is an Asp.net MVC app where Movie object is bound with the director and musicdirector names the user adds. So, the first 4 lines are done implicitly by MVC and think all the other lines are in the service layer. Am I missing something as this is a very basic scenario and the framework should handle it? Of course, one solution to correct this problem is to create a new Movie object and assign the records from db which I don't want to do as I have to copy all the properties from the movie object sent by controller. How can I solve this problem? </p> <p>Also this works correctly in Self-Tracking Entities. Is this some kind of a limitation to POCO and it would be great if someone can explain the behavior? </p>
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