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PONew child inserts existing parent in Entity Framework 4
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  1. PONew child inserts existing parent in Entity Framework 4
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    copied!<p>When I try to add new child relations to an existing parent object, <em>entity tries to insert the parent object as <strong>new</strong>, instead of updating it as <strong>modified</em></strong>. I get an error saying its trying to <strong><em>insert a duplicate key</em></strong>. </p> <p>This is really stumping me, it wasn't behaving like this until I updated the model with a new relation (via update from database, not code first). Other tables in the same context, with the same many-to-many pattern <strong>do not cause this error!</strong></p> <p>I've found that if I add my child object to the context, carefully setting the ID values, not the navigation properties, it will save fine. <em>But the fix-up process isn't adding the child object to the navigation collection</em>, wich cause logic issues in other places.</p> <p>My model has a many to many relation like this:</p> <p>option -&lt; optionUnit >- Unit</p> <p>Both Option and Unit objects are <strong>existing</strong> and <strong>loaded</strong> into the context.</p> <p>Normally I would make the bridge table and set the navigation properties like below:</p> <pre><code>bridge = new OptionUnit() { OptionUnitId = Guid.NewGuid(), Unit = SelectedUnit, Option = SelectedOption, }; //Context.OptionUnits.Add(bridge); //added to context via the navigation properties </code></pre> <p>But when I do this time, entity tried to insert SelectedOption as new (even though its entity state is modifed at time of the save, not new or detached).</p> <p>To get around this I've had to make the bridge and set the id's only. I get no error on save, but its not automatically added to SelectedOption.OptionUnits via fix-up like I would expect. If i add it to the collection manually, I get the save error again.</p> <pre><code>bridge = new OptionUnit() { OptionUnitId = Guid.NewGuid(), //Unit = SelectedUnit, UnitId = SelectedUnit.UnitId, //Option = SelectedOption, OptionId = SelectedOption.OptionId, }; Context.OptionUnits.Add(bridge); </code></pre> <p>This seems to be only happening for relations on the Options Entity. The other relation, between optionUnit >- Unit has no problems and works as expected.</p> <p>It seems like theres somethign wrong with the relations, but I'm not sure where to look. I need to know whats causing this behaviour, how to fix it, and how to prevent it from happening in the future.... </p>
 

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