Django Rest Framework serilize relations - django

Question

How to serialize a fields in related models.
I got a models:
class Order(models.Model):
order_id = models.BigIntegerField(verbose_name='Order ID', unique=True)
order_name = models.CharField(verbose_name='Order name', max_length=255)
order_type = models.IntegerField(verbose_name='Campaign type')
class Types(models.Model):
delimiter = models.CharField(verbose_name='Delimiter', max_length=255)
status = models.BooleanField(verbose_name='Status', default=True)
title = models.CharField(verbose_name='Title', max_length=255)
class User(models.Model):
name = models.CharField(verbose_name='User name', max_length=200, unique=True)
class Report(models.Model):
order = models.ForeignKey(Order, to_field='order_id', verbose_name='Order ID')
user = models.ForeignKey(User, verbose_name='User ID')
ad_type = models.ForeignKey(Types, verbose_name='Type')
imp = models.IntegerField(verbose_name='Total imp')
month = models.DateField(verbose_name='Month', default=datetime.datetime.today)
View:
class ReportLisAPIView(ListAPIView):
serializer_class = ReportSerializer
def get_queryset(self):
month = parse_date(self.kwargs['month']) - relativedelta(day=1)
queryset = (
Report.objects.filter(month=month)
.values_list(
'user', 'user__name', 'order__order_id',
'order__order_name', 'order__order_type'
).all().annotate(Sum('imp'))
)
return queryset
Serializer:
class ReportSerializer(ModelSerializer):
class Meta:
model = Report
depth = 1
I need to get all field like in 'queryset' in get_queryset()
but I got an error:
Got AttributeError when attempting to get a value for field imp on
serializer ReportSerializer. The serializer field might be named
incorrectly and not match any attribute or key on the tuple
instance. Original exception text was: 'tuple' object has no attribute
'imp'.
But if I return in get_queryset() just Report.objects.filter(month=month).all() I'll get all objects and related object with all field, without aggregate of imp and not grouping.
So the question is how to make serializer return structure that set in queryset?

Answer 1

The get_queryset method requires to return a queryset but you are returning a tuple beacause of values_list. Either drop it to return a queryset or go with a more generic view like APIView.

Answer 2

I found a way how to do it.
As I use .values_list() it return list object instead of queryset object. So for serializer do understand what is inside the list I defined all fields in serializer. And in to_representation() I return dictionary like it should be.
Serializer:
class ReportSerializer(serializers.ModelSerializer):
user = serializers.IntegerField()
user_name = serializers.CharField()
order_id = serializers.IntegerField()
order_name = serializers.CharField()
order_type = serializers.IntegerField()
imp = serializers.IntegerField()
class Meta:
model = Report
fields = [
'user', 'user_name', 'order_id', 'order_name',
'order_type', 'imp'
]
depth = 1
def to_representation(self, instance):
Reports = namedtuple('Reports', [
'user',
'user_name',
'order_id',
'order_name',
'order_type',
'imp',
])
return super(ReportSerializer, self).to_representation(
Reports(*instance)._asdict()
)
View:
class ReportLisAPIView(ListAPIView):
serializer_class = ReportSerializer
def get_queryset(self):
month = parse_date(self.kwargs['month']) - relativedelta(day=1)
queryset = (
Report.objects.filter(month=month)
.values_list(
'user', 'user__name', 'order__order_id',
'order__order_name', 'order__order_type'
).all().annotate(Sum('imp'))
)
return queryset
def list(self, *args, **kwargs):
queryset = self.get_queryset()
serializer = self.serializer_class(queryset, many=True)
# actualy that's it! part of which is below can be pass and just
# return Response(serializer.data)
result = {
'month': parse_date(self.kwargs['month']).strftime('%Y-%m'),
'reports': []
}
inflcr = {}
for item in serializer.data:
inflcr.setdefault(item['user'], {
'id': item['user'],
'name': item['user_name'],
'campaigns': []
})
orders = {
'id': item['order_id'],
'name': item['order_name'],
'type': item['order_type'],
'impressions': item['imp'],
}
inflcr[item['user']]['campaigns'].append(orders)
result['reports'] = inflcr.values()
return Response(result)