title: Update M2M relationship django rest framework (many=true)
body: <p>I try to update a channel:</p>
  
  <pre><code>PUT
  content [{'url': 'http://localhost:8000/api/movies/2', 'title': u'Ariel', 'backdrop_path': u'/z2QUexmccqrvw1kDMw3R8TxAh5E.jpg', 'popularity': 0.082, 'poster_path': u'/8ld3BEg8gnynRsfj2AzbLocD8NR.jpg', 'release_date': datetime.date(1988, 10, 21), 'runtime': 69L, 'tagline': u'', 'vote_average': 9.0, 'vote_count': 0L}]
  csrfmiddlewaretoken XXXXXXXXXXXXXXXXXXXXXXXXXXx
  name    cody private
  owner   http://localhost:8000/api/users/1
  private 1
  </code></pre>
  
  <p>And I get this error:</p>
  
  <pre><code>instance should be a queryset or other iterable with many=True
  </code></pre>
  
  <p>And here is the code you need to understand what's going on.</p>
  
  <pre><code>class Channel(models.Model):
      """
      A channel is a "container" for a users movies and television shows.
      """
      PUBLIC_VISIBILITY, PRIVATE_VISIBILITY = 0, 1
      VISIBILITY_CHOICES = (
          (PUBLIC_VISIBILITY, 'public'),
          (PRIVATE_VISIBILITY, 'private'),
      )
      owner = models.ForeignKey(User, related_name='owned_channels')
      name = models.CharField(max_length=60)
      content = models.ManyToManyField(Movie, db_table='channel_contents',
                                       related_name='channels', null=True, blank=True, default=None)
      subscribers = models.ManyToManyField(User, db_table='channel_subscribers',
                                           related_name='subscribed_channels', null=True, blank=True, default=None)
      created = models.DateTimeField(auto_now_add=True)
      last_mod = models.DateTimeField(auto_now=True)
      query = models.CharField(max_length=255, default='')
      private = models.IntegerField(choices=VISIBILITY_CHOICES, default=PRIVATE_VISIBILITY)
  
      default = models.BooleanField(default=False)
  
  
  class Movie(models.Model):
      id = models.BigIntegerField(primary_key=True)
      adult = models.BooleanField()
      backdrop_path = models.ImageField(upload_to='backdrop/')
      budget = models.IntegerField(blank=True, null=True)
      genres = models.ManyToManyField('Genre',
                                      through='MovieGenre',
                                      blank=True, null=True)
      homepage = models.URLField(blank=True, null=True)
      imdb_id = models.CharField(max_length=20, blank=True, null=True)
      original_title = models.CharField(max_length=100)
      overview = models.TextField(blank=True, null=True)
      popularity = models.FloatField(blank=True, null=True)
      poster_path = models.ImageField(upload_to='poster/')
      release_date = models.DateField(blank=True, null=True)
      revenue = models.IntegerField(blank=True, null=True)
      runtime = models.IntegerField(blank=True, null=True)
      tagline = models.CharField(max_length=200, blank=True, null=True)
      title = models.CharField(max_length=100, db_index=True)
      vote_average = models.FloatField(blank=True, null=True)
      vote_count = models.IntegerField(blank=True, null=True)
      actors = models.ManyToManyField('Actor',
                                      through='MovieActor',
                                      blank=True, null=True)
      directors = models.ManyToManyField('Director',
                                         through='MovieDirector',
                                         blank=True, null=True)
      production_companies = models.ManyToManyField(
          'ProductionCompany',
          through='MovieProduction',
          blank=True, null=True)
  </code></pre>
  
  <p>Channel serializing code:</p>
  
  <pre><code># Routes
  url(r'^channels$', ChannelList.as_view(), name='channel-list'),
  url(r'^channels/(?P&lt;pk&gt;\d+)$', ChannelDetail.as_view(), name='channel-detail'),
  
  # Views
  class ChannelList(generics.ListCreateAPIView):
      """
      API endpoint that represents a list of users.
      """
      model = Channel
      serializer_class = ChannelSerializer
  
  class ChannelDetail(generics.RetrieveUpdateDestroyAPIView):
      """
      API endpoint that represents a single users.
      """
      model = Channel
      serializer_class = ChannelSerializer
  
  # Serializer
  class ChannelSerializer(serializers.HyperlinkedModelSerializer):
      content = MovieSerializer(many=True)
  
      class Meta:
          model = Channel
          fields = ('url', 'owner', 'name', 'content', 'private')
  </code></pre>