title: Post to nested fields with Django Rest Framework serializers
body: <p>I have setup my serializer to return nested content successfully.</p>
  
  <p>However, I have not been able to post data within the nested fields.</p>
  
  <p>I don't get an error when posting the data- but it only posts to the non-nested fields.</p>
  
  <p>I would like for it to take the "name" field OR primary key (of model "TAG") for posting item.</p>
  
  <p>Models.py</p>
  
  <pre><code>class Tag(models.Model):
      name = models.CharField("Name", max_length=5000, blank=True)
      def __str__(self):
          return self.name
  
  class Movie(models.Model):
      title = models.CharField("Whats happening?", max_length=100, blank=True)
      tag = models.ManyToManyField('Tag', blank=True)
      def __str__(self):
          return self.title
  </code></pre>
  
  <p>Serializers.py:</p>
  
  <pre><code>class TagSerializer(serializers.ModelSerializer):
      taglevel = filters.CharFilter(taglevel="taglevel")
      class Meta:
          model = Tag
          fields = ('name', 'taglevel', 'id')
  
  class MovieSerializer(serializers.ModelSerializer):
      tag = TagSerializer(many=True, read_only=False)
      info = InfoSerializer(many=True, read_only=True)
      class Meta:
          model = Movie
          fields = ('title', 'tag', 'info')
  
  def validate(self, data):
      print(self.initial_data.__dict__)
      data['tag_name'] = []
      if 'tag' in self.initial_data.keys():
          for entry in self.initial_data['tag']:     
              data['tag_name'].append(entry['name'])
      return data
  
  def create(self, validated_data):
      print(validated_data)
      tags_data = validated_data.pop('tag')
      movie = Task.objects.create(**validated_data)
      for tag_data in tags_data:
          Movie.objects.create(name=name, **tag_data)
      return movie
  </code></pre>
  
  <p>Sample of posting data:</p>
  
  <pre><code>r = requests.post('http://localhost:8000/api/Data/',{ "title": "TEST_title", "tag": [ { "name": "test1", "name": "test2" } ], "info": [] })
  </code></pre>