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POEntity Framework Code First - Adding 1:many through aggregate root
 

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  1. POEntity Framework Code First - Adding 1:many through aggregate root
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    <p>I have a question regarding adding children to a root entity in Entity Framework 4.1 CF. </p> <p>Considering the following infrastructure Entity base class and two POCOs: </p> <pre><code>public abstract class EntityBase&lt;TKeyDataType&gt; { [Key] public TKeyDataType Id { get; set; } // Equality methods ommitted for brevity... } public class Foo : EntityBase&lt;int&gt;, IAggregateRoot { public string Foo1 { get; set; } public virtual ICollection&lt;FooSibling&gt; Siblings { get; set; } } public class FooSibling : EntityBase&lt;int&gt; { public string SiblingPropFoo { get; set; } public int FooId { get; set; } public Foo Foo { get; set; } } </code></pre> <p>Notice that <code>Foo</code> implements <code>IAggregateRoot</code> (just an empty interface - think of it as metadata in the "data about data" context). </p> <p>So far, so good. If I run this, EF creates the database with the appropriate 1:many relationship.</p> <p>The only fluent mapping I have on these two entities are: </p> <pre><code>modelBuilder.Entity&lt;Foo&gt;() .HasMany(x =&gt; x.Siblings) .WithRequired(x=&gt;x.Foo) .WillCascadeOnDelete(true); </code></pre> <p>No <code>FooSibling</code> without a <code>Foo</code>. Blow away a <code>Foo</code>, you blow away all its sibling. This piece works.</p> <p>The issue is when adding FooSiblings POCO to the Foo POCO, I have to use unique negative numbers as shown in this service method:</p> <pre><code>public ResponseBase UpdateBy(RequestBase&lt;Foo&gt; request) { ResponseBase response = new ResponseBase(); try { Foo foo = FooRepository.FirstOrDefault(x =&gt; x.Id == request.Entity.Id); // Dummy adds to test associations. // These come back on the Foo inside the request, but I'm explicitly putting them here // for the purpose of this question. request.Entity.Siblings.Add(new FooSibling() { Id = -2, SiblingPropFoo = "Prop1", SiblingPropFoo2 = "Prop2" }); request.Entity.Siblings.Add(new FooSibling() { Id = -1, SiblingPropFoo = "Prop1", SiblingPropFoo2 = "Prop2" }); // Update Foo's scalars and children (mapping is Foo-&gt;Foo) foo = AutoMapper.Mapper.Map(request.Entity, foo); UnitOfWork.Commit(); response.Success = true; } catch (Exception e) { response.Success = false; response.Message = e.Message; } return response; } </code></pre> <p>Once the <code>UnitofWork.Commit()</code> is called (it just calls <code>SaveChanges</code> of the context - no magic here), all is well... </p> <p>However, if I don't use unique negative numbers like and just try to set its parent, like this: </p> <pre><code>request.Entity.Siblings.Add(new FooSibling() { Foo = foo, SiblingPropFoo = "Prop1", SiblingPropFoo2 = "Prop2" }); request.Entity.Siblings.Add(new FooSibling() { Foo = foo, SiblingPropFoo = "Prop1", SiblingPropFoo2 = "Prop2" }); </code></pre> <p>Only one gets persisted to the database. </p> <p>The only other way I know of to do it without using negative numbers is to use the FooSiblings DbSet directly in the service method: </p> <pre><code>IRepository&lt;FooSibling&gt; siblingRepo = new CookieCutterEntityFrameworkRepository&lt;FooSibling&gt;(UnitOfWork); siblingRepo.Insert(new FooSibling() { FooId = foo, .... }); </code></pre> <p>My CookieCutter repository is abstracting all the DbSet stuff, etc.</p> <p>But ... stripping off all the abstraction and generic voodoo for clarity, the question really comes down to is there a way to update my Foo POCO (the root Entity) and add new siblings through one DbSet without using negative numbers? </p> <p>For reference (without abstraction using pure DbContext): </p> <pre><code>// This works (using multiple DbSets/Repositories always make life easier...) Ctx.Foos.Update(foo); Ctx.FooSiblings.Add(new FooSibling() { Foo = foo, ... }); Ctx.FooSiblings.Add(new FooSibling() { Foo = foo, ... }); Ctx.SaveChanges(); // This works too (using negative number trick - foo scalar properties get // updated and the siblings get persisted to the database properly). foo.Siblings.Add(new FooSibling() { Id = -2, ....}); foo.Siblings.Add(new FooSibling() { Id = -1, ....}); Ctx.Foos.Update(foo); Ctx.SaveChanges(); // This doesn't work (but it's what I'm striving for to drive everything off the root). foo.Siblings.Add(new FooSibling() { Foo = foo }); foo.Siblings.Add(new FooSibling() { Foo = foo }); Ctx.Foos.Update(foo); Ctx.SaveChanges(); </code></pre> <p>In the last case (the non-working case), I'm striving to configure it in a fashion where it picks up any changes to the Foo POCO itself. </p> <p>I've tried with Proxies turned off and on. Also, in the way this is setup, the context remains in scope for the life of the entire HTTP request. </p> <p>If not possible, what suggestion(s) would you give? </p>
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