title: The property 'Id' is part of the object's key information and cannot be modified
body: <p>i'm using Entity Framework 4.0 and having a silly problem that i can't figure out.</p>
  
  <p>I have two tables:</p>
  
  <ol>
  <li>Contact: Id (primary key), Value, ContactTypeId (foreign key to ContactType)</li>
  <li>ContactType: Id (Primary key), Type (Home, Cell, Work, etc.)</li>
  </ol>
  
  <p>Entity Framework created the following two entities:</p>
  
  <ol>
  <li>Contact: Id, Value, ContactType (Navigation Property)</li>
  <li>ContactType: Id, Type, Contact (Navigation Property)</li>
  </ol>
  
  <p>I'm using the following code to get the contact and update the contact type for that particular contact:</p>
  
  <pre><code>Contact contact = dbContext.Contacts.Single(c =&gt; c.Id == 12345);
  contact.ContactType.Id = 3;
  </code></pre>
  
  <p>Throws the following exception: </p>
  
  <pre><code>The property 'Id' is part of the object's key information and cannot be modified.
  </code></pre>
  
  <p>It looks so simple! I don't get it!</p>