Django + rest-framework: serialize arbitrary query - json

Question

I have three classes representing different sections in my models: SectionA, SectionB, SectionC.
Each of these sections have associated a set of items (class Item in my model).
I would like to get a json similar to this:
{
"sectionA": [
{
"id": 1,
"picture": "car_pic1",
"category": "cat1"
},
{
"id": 3,
"picture": "car_pic1",
"category": "cat2"
},
{
"id": 5,
"picture": "car_pic1",
"category": "cat3"
}
],
"sectionB": [
{
"id": 2,
"picture": "car_pic1",
"category": "cat8"
},
{
"id": 4,
"picture": "car_pic1",
"category": "cat9"
},
{
"id": 7,
"picture": "car_pic1",
"category": "cat10"
},
],
"sectionC": [
{
"id": 9,
"picture": "car_pic1",
"category": "cat9"
},
{
"id": 10,
"picture": "car_pic1",
"category": "cat9"
},
{
"id": 11,
"picture": "car_pic1",
"category": "cat10"
},
]
}
This json displays any three items associated to each section.
I would like to know how can I implement this using rest-framework. Basically I need to perform a query retrieving the three items for each section (since this json is not associated to a model object) and serialize all this into the json. I'm not sure where or how to perform these queries and I didn't have any success so far.

Answer 1

Finally I did it slightly different. My view just creates a dictionary with each section and its associated items:
class SectionList(APIView):
"""
List three objects for each section.
"""
def generate_data(self):
#query to get the items of each section
list_items = []
list_items.append({"section" : "sectionA", "items" : secA_items})
list_items.append({"section" : "sectionB", "items" : secB_items})
list_items.append({"section" : "sectionC", "items" : secC_items})
return list_items;
def get(self, request, format=None):
section_list = self.generate_data()
serializer = SectionSerializer(section_list)
return Response(serializer.data)
And this is the serializer I used:
class SectionSerializer(serializers.Serializer):
section = serializers.CharField(max_length=200)
items = ItemSerializer(many=True)