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    <p>Stubs are generally only effective for <code>1-*</code> relationships. <code>*-*</code> relationships introduce a different set of challenges.</p> <p>Namely that when you attach both ends - unlike <code>1-*</code> - you still have no idea if the relationship already exists or not.</p> <p>So that means that this code:</p> <pre><code>if (issue.Scopes.Contains(thisScope)) </code></pre> <p>Is probably going to return false every time.</p> <p>What I would do is this:</p> <pre><code>edmx.Issues.Attach(issue); UpdateModel(issue); // or ctx.LoadProperty(issue, "Scopes") if it is a POCO class. issue.Scopes.Load(); // hit the database to load the current state. </code></pre> <p>Now you need to find out what you need to add &amp; remove from issue.Scopes. You can do this by comparing based on ID.</p> <p>i.e. if you have a set of Scope IDs you want to have related to the issue (relatedScopes)</p> <p>Then this code works out what to add and what to remove.</p> <pre><code>int[] toAdd = relatedScopes.Except(issue.Scopes.Select(s =&gt; s.ID)).ToArray(); int[] toRemove = issue.Scopes.Select(s =&gt; s.ID).Except(relatedScopes).ToArray(); </code></pre> <p>Now for toAdd you do this:</p> <pre><code>foreach(int id in toAdd) { var scope = new Scope{Id = id}; edmx.Scopes.Attach(scope); issue.Scopes.Add(scope); } </code></pre> <p>And for each scope you need to remove</p> <pre><code>foreach(int id in toRemove) { issue.Scopes.Remove(issue.Scopes.Single(s =&gt; s.ID == id)); } </code></pre> <p>By now the correct relationships should be formed.</p> <p>Hope this helps</p> <p><a href="http://twitter.com/adjames" rel="noreferrer">Alex</a></p> <p>Microsoft</p>
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    1. COThat's perfect! And looking at SQL profiler, it's only one "extra" call to the DB for the .Load(), but much cleaner way of adding/removing than the way I used to do it by hand with stored procedures. Thanks!
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    2. COJames nice answer. This is a common problem in many application (effectively add/removing tags). Isn't it time for a system level function to do this without a screen full of code? Something like *issue.Scopes.ReplaceWith(myScopes);*
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    3. CO@TFD yeah I hear you. Failing that, the EF team has lots on its plate, a simple extension method would do the trick though right?
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