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POEF Code First, create new object in collection with a proxy
 

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    <p>How can I create+persist+have-a-proxy-to a new instance of a code-first poco using only navigation property collections? In the bellow code, I show how you might want to do this, if using member functions to create POCOs that then create POCOs. You don't have a DbContext, but if you create an object and persist it using DbSet.Add, the returned object isn't a proxy, so you can't in turn use its DbSet.Add to add a different sub-object.</p> <p>In this code, if you call MailingList.AddIncomingMessage("my message"), you get an exception at the "OOPS" comment, because the created msg isn't a proxy and thus its Message.doodads property is null.</p> <pre><code>class Doodad { public int ID { get; set; } public string doodad { get; set; }; } class Message { public int ID { get; set; } public virtual MailingList mailingList { get; set; } public virtual ICollection&lt;Doodad&gt; doodads { get; set; } public string text { get; set; } public void GetDoodadCreateIfNeeded(string doodad) { try { // won't be found since we just created this Message return this.doodads.First(d =&gt; d.doodad == doodad); } catch (Exception e) { Doodad newDoodad = new Doodad() { doodad=doodad }; // OOPS! this.doodads == null, because its not a proxy object this.doodads.Add(newDoodad); return newDoodad; } } } class MailingList { public int ID { get; set; } public virtual ICollection&lt;Message&gt; messages { get; set; } public void AddIncomingMessage(string message) { var msg = new Message() { text=message }; // we have no Context, because we're in a POCO's member function this.messages.Add(msg); var doodad = msg.GetDoodadCreateIfNeeded("bongo drums"); } } </code></pre> <p>EDIT: sorry guys, I forgot to put the property accessors and ID in for this simplified case, but I am using them in the actual code.</p>
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    1. USSeth
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    1. COto anyone else running into this, check out Alex's comment on http://stackoverflow.com/questions/5974448/entityframework-4-1-dbcontext-changetracking-kills-performance
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      1. USSeth
 

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