title: Change Django Rest Framework serializers output structure?
body: <p>I have a Django model like this:</p>
  
  <pre><code>class Sections(models.Model):
      section_id = models.CharField(max_length=127, null=True, blank=True)
      title = models.CharField(max_length=255)
      description = models.TextField(null=True, blank=True)
  
  class Risk(models.Model):
     title = models.CharField(max_length=256, null=False, blank=False)
     section = models.ForeignKey(Sections, related_name='risks')
  
  class Actions(models.Model):
     title = models.CharField(max_length=256, null=False, blank=False)
     section = models.ForeignKey(Sections, related_name='actions')
  </code></pre>
  
  <p>And serializers like that :</p>
  
  <pre><code>class RiskSerializer(serializers.ModelSerializer):
     class Meta:
          model = Risk
          fields = ('id', 'title',)
  
  class ActionsSerializer(serializers.ModelSerializer):
      class Meta:
          model = Actions
          fields = ('id', 'title',)
  
  class RiskActionPerSectionsSerializer(serializers.ModelSerializer):
     risks = RiskSerializer(many=True, read_only=True)
     actions = ActionsSerializer(many=True, read_only=True)
  
     class Meta:
          model = Sections
          fields = ('section_id', 'risks', 'actions')
          depth = 1
  
     def to_representation(self, instance):
          response_dict = dict()
          response_dict[instance.section_id] = {
          'actions': HealthCoachingActionsSerializer(instance.actions.all(), many=True).data,
          'risks': HealthCoachingRiskSerializer(instance.risks.all(), many=True).data
      }
      return response_dict
  </code></pre>
  
  <p>When accessing the RiskActionPerSectionSerializer over a view, I get the following output:</p>
  
  <pre><code>[
  {
      "section 1": {
          "risks": [],
          "actions": []
      }
  },
  {
      "section 2": {
          "risks": [],
          "actions": []
      }
  },
  .....
  ]
  </code></pre>
  
  <p>It s fine but I would prefer to have that : </p>
  
  <pre><code>[
  
      "section 1": {
          "risks": [],
          "actions": []
      },
      "section 2": {
          "risks": [],
          "actions": []
      }
  .....
  ]
  </code></pre>
  
  <p>Also why is it returning an array by default [] and not an object for example like:</p>
  
  <pre><code>{
   "count": 0,
   "next": null,
   "previous": null,
   "results": []
   }
  </code></pre>