title: DRF how to save a model with a foreign key to the User object
body: <p>I have the following model:</p>
  
  <pre><code>class Journal(models.Model):
      project_name = models.TextField()
      intro = models.TextField(blank=True)
      start_time = models.DateTimeField()
      end_time = models.DateTimeField()
      creator = models.ForeignKey(User)
      group = models.OneToOneField(Group)
      contact_info = models.TextField(blank=True)
      allow_anon = models.BooleanField(default=True)
      created = models.DateTimeField(auto_now_add=True)
  </code></pre>
  
  <p>I would like to save a record of this model when users submit a form. The values of all the required fields are submitted along with the form so I assume <strong>request.data</strong> would have them in it except for the <code>creator</code> field. </p>
  
  <p>Since I use token authentication, a token that can identify the user is passed within the HTTP header. According to <a href="https://stackoverflow.com/questions/28345842/getting-custom-header-on-post-request-with-django-rest-framework">this post</a>, I can use <strong>request.META('whatever')</strong> to pull out this token key from the header. Then I will be able to retrieve the user instance based on the token.</p>
  
  <p>So far so good, my question is the next step, how can I write a serializer that can take <strong>request.data</strong> and a user instance when saving?</p>
  
  <p>I think I should use a <code>ModelSerializer</code> based on the model defined above. But how can I turn the user instance into a serializable form so that the <code>ModelSerializer</code> can consume while saving?</p>