title: How can I update entity with its children? Patch method doesn't work
body: <p>I must update my entity with its children list as shown here:</p>
  
  <pre><code> public class Entity1 
   { 
      int Id{get;set;} 
      ObservableCollection&lt;Child1&gt; ChildrenList {get;set;} 
      string Name{get;set;}
   }
  
  public class Child1
  {
      string Nome{get;set;}
      string Cognome {get;set;}
  }
  </code></pre>
  
  <p>I implemented patch method in this way:</p>
  
  <pre><code>[AcceptVerbs("PATCH", "MERGE")]
  public async Task&lt;IHttpActionResult&gt; Patch([FromODataUri] int key, Delta&lt;Entity1&gt; entityDelta)
  {
  
              if (!ModelState.IsValid)
              {
                  return BadRequest(ModelState);
              }
              var entity = await Context.Entity1.FindAsync(key);
              if (entity == null)
              {
                  return NotFound();
              }
              entityDelta.Patch(entity);
  
              try
              {
                  await Context.SaveChangesAsync();
              }
              catch (DbUpdateConcurrencyException)
              {
                  return NotFound();
              }
              return Updated(entity);
  }
  </code></pre>
  
  <p>but when I try to call it from fiddler in this way:</p>
  
  <pre><code>Url: http://localhost/odata4/Entity1(1)/  with patch request
  
  Request Headers: Content-Type: application/json
  
  Request Body: 
  {
  Name: "pippo2",
  ChildrenList:[{
  Nome: "Test",
  Cognome: "Pippo"
  }]
  }
  </code></pre>
  
  <p>It gives an error in Model.isValid Property and specified return this error:</p>
  
  <blockquote>
    <p>Cannot apply PATCH to navigation property 'ChildrenList' on entity
    type 'Entity1'.</p>
  </blockquote>
  
  <p>How can I solve it? Is the patch method the correct method to use? </p>