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PO Insert new object with existing object
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  1. PO Insert new object with existing object
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    copied!<p>I am new to EF 4 and this is what I have done so far:</p> <ul> <li>Create an edmx file based on my database</li> <li>Create a code generation for my objects (POCO). Now I have a model1.tt, when expanded I see al my classes</li> <li>Create a repository for each class, based on IRepository</li> </ul> <p>Now, I am working with two objects, A and B. Object A has a property of type B. In my winform I have a combo filled with objects of type B. When the save button is pressed, a new instance of class A is created and all the properties are set. The object B property is set as follows:</p> <pre><code>objectA.myObjectB = (objectB)cmbBObjects.selectedItem; </code></pre> <p>Then I create a repository for objectA and call the save method. In this save method I have this code±</p> <pre><code>public bool Save(ObjectA obj) { using(MyContext context = new MyContext()) { context.objectAs.AddObject(obj); context.SaveChanges(); } } </code></pre> <p>This code, does save a new entry to the database, but it is also creating a new record for object B! I don't want this, because object B already exists in the database! (I have selected this one from the combobox).</p> <p>This is how I fill my combobox:</p> <p>In the objectB repository:</p> <pre><code>public IList&lt;ObjectB&gt; GetAll() { using(MyContext context = new MyContext()) { IList&lt;ObjectB&gt; objects = context.objectBs.ToList(); return objects; } } </code></pre> <p>In my form:</p> <pre><code>ObjectBRepository rep = new ObjectBRepository(); IList&lt;ObjectB&gt; objects = rep.GetAll; cmbBObjects.Datasource = objects; // etc.. </code></pre> <p>So my question is, what do I have to do to save object A without creating a new record for objectB?</p>
 

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