title: Django Rest Framework - Updating a foreign key
body: <p>I am a bit frustrated with this problem using the Django Rest Framework:</p>
  
  <p>I am using a <strong>viewset</strong>, with a <code>custom serializer</code>. This serializer has its <code>depth set to 1</code>. When i query this viewset I get the correct representation of data for example:</p>
  
  <pre><code>data = {
    id: 1,
    issue_name: 'This is a problem',
    status: {
      id: 3,
      name: 'todo'
    }
  }
  </code></pre>
  
  <p>The <strong>problem</strong> comes in when I need to <strong>update the status</strong>. For example if I want to select another status for this issue, for example:</p>
  
  <pre><code>status_new = {
     id: 4,
     name: 'done'
  }
  </code></pre>
  
  <p>I send the following PATCH back to the server, this is the output:</p>
  
  <pre><code>data = {
    id: 1,
    issue_name: 'This is a problem',
    status: {
      id: 4,
      name: 'done'
    }
  
  }
  </code></pre>
  
  <p>However, the status does not get updated. Infact, it is not even a part of the validated_data dictionary. I have read that nested relations are read-only. Could someone please tell me what I need to do this in a simple way?</p>
  
  <p>Would really be obliged.</p>
  
  <p>Thanks in advance</p>