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POEntity Framework - adding new items via a navigation property
 

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    <p>I have come across what appears to be very peculiar behaviour using entity framework 4.0.</p> <p>I have a User entity, which has a Company (A Company has many Users).</p> <p>If I do this, everything works as expected and I get a nice shiny new user in the database:</p> <pre><code>var company = _model.Companies.First(); company.Users.Add(new User(1, "John", "Smith")); _model.SaveChanges(); </code></pre> <p>However, if I do this, then I get nothing new in the database, and no exceptions thrown:</p> <pre><code>var existingUser = _model.Users.First(); var company = existingUser.Company; company.Users.Add(new User(1, "John", "Smith")); _model.SaveChanges(); </code></pre> <p>So it appears that if I add a User to the Company that is pulled directly from the model, then everything works fine. However if the User is added to a Company that is pulled as a navigation property of another object, then it doesn't work.</p> <p>Can someone tell me if this is expected behaviour, or if there is something I can do to make it so that it is?</p> <p>Thanks!</p> <h2>Edit</h2> <p>To clarify what I mean by "it doesn't work";</p> <ul> <li>Stepping through the code shows the execution pointer going past all lines without throwing an exception.</li> <li>No new row is added to the database</li> <li>If I check company.Users in quick watch, the new user has indeed been added to the company - it's just not being saved to the database.</li> </ul> <p>I've done a little more playing, and it seems that if I do this, I get an exception:</p> <pre><code>var existingUser = _model.Users.First(); var company = existingUser.Company; _model.ObjectStateManager.GetObjectStateEntry(company); </code></pre> <p>The exception is:</p> <blockquote> <p>System.InvalidOperationException: The ObjectStateManager does not contain an ObjectStateEntry with a reference to an object of type 'ABC.DEF.Company'.</p> </blockquote> <p>Doing that for the first (working) scenario provides me with an ObjectStateEntry back without throwing an exception.</p>
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