django-rest-framework aggregated sum fields - django

Question

serializers.py
class BuildPlanNewSerializer(serializers.ModelSerializer):
StatusName = serializers.CharField(source='BuildPlanStatusID.StatusName', read_only=True)
# build_plan_list_new = serializers.StringRelatedField(many=True, read_only=True)
total_build_plan_list = serializers.SerializerMethodField()
def get_total_build_plan_list(self, language):
return language.build_plan_list_new.count()
class Meta:
model = BuildPlanNew
fields = ('StatusName', 'total_build_plan_list')
class BuildPlanListNewSerializer(serializers.ModelSerializer):
sku = serializers.CharField(source='ProductID.sku', read_only=True)
class Meta:
model = BuildPlanListNew
fields = "__all__"
models.py
class BuildPlanNew(models.Model):
emp_id = models.ForeignKey(Employee, on_delete=models.CASCADE, null=True, blank=True)
StartDate = models.DateTimeField()
EndDate = models.DateTimeField()
BuildPlanStatusID = models.ForeignKey(GlobalStatus, on_delete=models.CASCADE)
class BuildPlanListNew(models.Model):
BuildPlanID = models.ForeignKey(BuildPlanNew, on_delete=models.CASCADE, null=True, blank=True, related_name="build_plan_list_new")
ProductID = models.ForeignKey(Product, on_delete=models.CASCADE)
TotalPlanQty = models.IntegerField()
TotalBuiltQty = models.IntegerField())
QtyPreset = models.IntegerField(default=None, max_length=256)
Objective = models.IntegerField(default=None, max_length=256)
QtyAssigned = models.IntegerField(default=None, max_length=256)
view.py
class BuildPlanNewView(viewsets.ModelViewSet):
queryset = BuildPlanNew.objects.all()
serializer_class = BuildPlanNewSerializer
class BuildPlanListNewView(viewsets.ModelViewSet):
queryset = BuildPlanListNew.objects.all()
serializer_class = BuildPlanListNewSerializer
Result i am getting:
[{
"StatusName": "1234",
"total_build_plan_list": 0
}]
Result i am expecting:
[{
"StatusName": "1234",
"total_build_plan_list": 0,
"QtyPreset_count":20,
"Objective_count":30
}]
Here i wants to fetch aggregated sum and average from foreign key table.
Need QtyPreset_count sum as QtyPreset_count
Need Objective_count sum as as Objective_count
I have shared my models views and serializers
Please have a look

Answer 1

just add fields to your serializer like you have done so far
from django.db.models import Sum, Avg
class BuildPlanNewSerializer(serializers.ModelSerializer):
StatusName = serializers.CharField(source='BuildPlanStatusID.StatusName', read_only=True)
# build_plan_list_new = serializers.StringRelatedField(many=True, read_only=True)
total_build_plan_list = serializers.SerializerMethodField()
QtyPreset_count = serializers.SerializerMethodField()
Objective_count = serializers.SerializerMethodField()
def get_total_build_plan_list(self, language):
return language.build_plan_list_new.count()
def get_QtyPreset_count(self, language):
return language.build_plan_list_new.aggregate(Sum('QtyPreset'))
# return language.build_plan_list_new.aggregate(Avg('QtyPreset')) if you need it's average
def get_Objective_count(self, language):
return language.build_plan_list_new.aggregate(Sum('Objective'))
class Meta:
model = BuildPlanNew
fields = ('StatusName', 'total_build_plan_list')