title: Django REST Framework: How can I set a FK as optional?
body: <p>I'm trying to set that a Foreign Key field is optional. </p>
  
  <p>I have already added "null=True, blank=True" to the "group" field in my models.py file but it's also required.</p>
  
  <p>Here is my models.py code:</p>
  
  <pre><code>class Record(Timestampable):
    uuid = CharField(max_length=256, primary_key=True, editable=False)
    code = CharField(max_length=32, blank=True)
    name = CharField(max_length=256, blank=True)
    group = ForeignKey('self', null=True, blank=True, related_name='members')
  </code></pre>
  
  <p>Here is my serializers.py code:</p>
  
  <pre><code>class RecordSerializer(ModelSerializer):
    class Meta:
      model = Record
      fields = ('uuid', 'code', 'name', 'group')
  </code></pre>