Django DRF serializers, how to add new field, fusion of two models? - django

Question

I have two models, I have to make an endpoint where the results of two tables should appear in the json, which have a fongeringkey that joins them.
My code is the following:
models.py
class Property(models.Model):
address = models.CharField(max_length=120)
city = models.CharField(max_length=32)
price = models.BigIntegerField()
description = models.TextField(blank=True, null=True)
year = models.IntegerField(blank=True, null=True)
class Meta:
managed = False
db_table = 'property'
class StatusHistory(models.Model):
property = models.ForeignKey(Property, on_delete=models.CASCADE)
status = models.ForeignKey(Status, on_delete=models.CASCADE)
update_date = models.DateTimeField()
class Meta:
managed = False
db_table = 'status_history'
views.py
class StandardResultsSetPagination(PageNumberPagination):
page_size = 10
page_size_query_param = "page_size"
max_page_size = 1000
class PropertyListView(viewsets.ModelViewSet):
http_method_names = ['get', 'head']
serializer_class = PropertyListSerializer
queryset = Property.objects.all()
pagination_class = StandardResultsSetPagination
def get_serializer_class(self):
if self.action == 'list':
return PropertyListSerializer
return PropertyListSerializer
def get_queryset(self):
queryset = Property.objects.all()
if self.request.GET.get('year'):
queryset = queryset.filter(year=self.request.GET.get('year'))
if self.request.GET.get('city'):
queryset = queryset.filter(city=self.request.GET.get('city'))
if self.request.GET.get('status'):
queryse = queryset.filter(statushistory__status=self.request.GET.get('status'))
else:
queryset = queryset.order_by('-year')
return queryset
def list(self, request):
queryset = self.filter_queryset(self.get_queryset())
page = self.paginate_queryset(queryset)
if page is not None:
serializer = self.get_serializer(page, many=True)
return self.get_paginated_response(serializer.data)
serializer = self.get_serializer(queryset, many=True)
return Response(serializer.data)
serializers.py
class PropertyListSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Property
fields = ('id', 'address', 'city', 'price', 'description', 'year')
class StatusHistoryListSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = StatusHistory
fields = ('property', 'status', 'update_date')
I can correctly filter the parameters, city, year(model Property) and above all status(model StatusHistory) with the following code snippet:
if self.request.GET.get('status'):
queryset = queryset.filter(statushistory__status=self.request.GET.get('status'))
My problem is how I show in my JSON Response the new field fusion of the two models statushistory__statustry adding the following in serializers.py
class PropertyListSerializer(serializers.HyperlinkedModelSerializer):
statushistory_set =StatusHistoryListSerializer(many=True)
class Meta:
model = Property
fields = ('id', 'address', 'city', 'price', 'description', 'year', 'statushistory_set')
class StatusHistoryListSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = StatusHistory
fields = ('property', 'status', 'update_date')
Without any result.

Answer 1

I think you could set related_name attribute in the foreign key field.
class StatusHistory(models.Model):
property = models.ForeignKey(Property, on_delete=models.CASCADE, related_name = 'status_histories')
status = models.ForeignKey(Status, on_delete=models.CASCADE)
...
And in the PropertyListSerializer,
class PropertyListSerializer(serializers.HyperlinkedModelSerializer):
status_histories = StatusHistoryListSerializer(many=True, read_only = True)
class Meta:
model = Property
fields = ('id', 'address', 'city', 'price', 'description', 'year', 'status_histories')
You can also get property field as an object in the StatusHistory like the following:
class StatusHistoryListSerializer(serializers.HyperlinkedModelSerializer):
property = PropertyListSerializer(read_only = True)
class Meta:
model = StatusHistory
fields = ('property', 'status', 'update_date')