title: Expanding on django forms
body: <p>I have a modelform, which has three required fields: <code>user</code>, <code>network</code>, and <code>position</code>. The <code>position</code> is pulled by <code>request.POST</code>, and the other two will be supplied outside of it. This is what I currently have:</p>
  
  <pre><code>form = StartForm(request.POST)
  form.save()
  </code></pre>
  
  <p>Obviously, this form is not validating, because I haven't provided the <code>user</code> and <code>network</code> instances. How do I add this additional information to the form? Conceptually, I'm looking for something like this:</p>
  
  <pre><code>form = StartForm(request.POST + user_id=10, network_id=20)
  form.save()
  </code></pre>