IntegrityError in djnago - django

Question

Can't find a solution to this error please help or show me how to fix this.
The error is showing as follows:
(1048, "Column 'targetDefn_id' cannot be null") this error is showing when I post data.
This is my views.py in Post method I m getting this error:
def setTarget(request):
if request.method == 'POST':
data=JSONParser().parse(request)
print(data)
serial=TargetSerializers(data=data)
print(serial)
if serial.is_valid():
serial.save()
print("done")
return JsonResponse(serial.data,status=status.HTTP_200_OK,safe=False)
return JsonResponse(serial.errors, status=status.HTTP_400_BAD_REQUEST)
This is my Serializer.py as follows:
class TargetSerializers(serializers.ModelSerializer):
targetDefn=serializers.SerializerMethodField()
roleId=serializers.SerializerMethodField()
empId=serializers.SerializerMethodField()
class Meta:
model = Target
fields = (
'id',
'targetDefn',
'roleId',
'empId',
'startDate',
'endDate',
'value'
)
def get_targetDefn(self,obj):
trgt = TargetDefination.objects.get(id=obj.targetDefn_id)
serial = TargetDefinationSerializers(trgt)
return serial.data
def get_empId(self,obj):
emp= Employee.objects.get(id=obj.empId_id)
serial= OnlyEmployeeSerializers(emp)
return serial.data
def get_roleId(self,obj):
role=Role.objects.get(id=obj.roleId_id)
serial=RoleSerializers(role)
return serial.data
This is models.py as follows:
class Target(models.Model):
targetDefn=models.ForeignKey(TargetDefination,on_delete=models.CASCADE)
roleId=models.ForeignKey(Role,on_delete=models.CASCADE)
empId=models.ForeignKey(Employee,on_delete=models.CASCADE)
startDate= models.DateField(default=datetime.date.today)
endDate= models.DateField(null=True,blank=True)
value=models.PositiveIntegerField(default=0)
def __str__(self):
return str(self.empId) + ' ' +str(self.targetDefn)
Updated:
My Post query:
{
"targetDefn": {
"id": 1,
"targetName": "MIN SALES",
"displayName": "MIN SALES"
},
"roleId": {
"id": 3,
"roleName": "CIO",
"description": "chief information officer",
"roleReportsTo": 5,
"roleReportsToName": "SeniorVP(M)"
},
"empId": {
"id": 2,
"empName": "Emp02",
"startDate": "2021-04-01",
"termDate": null
},
"startDate": "2021-05-11",
"endDate": "2021-05-20",
"value": "123"
}

Answer 1

Know that the SerializerMethodField is READ-ONLY. It means that the data of those fields will not be written in the database. They will be computed and sent to your user, but never written in the DB. So, when you're saving your serializer, those fields are ignored.
I've noticed that you've created SerializerMethodField for all your foreign keys, only for their get_[field] method to return literally the serialized object. So why not simply use their nested-serializer right away?
class TargetSerializers(serializers.ModelSerializer):
targetDefn=TargetDefinationSerializers()
roleId=OnlyEmployeeSerializers()
empId=serializers.SerializerMethodField()
class Meta:
model = Target
fields = (
'id',
'targetDefn',
'roleId',
'empId',
'startDate',
'endDate',
'value'
)
If you cannot get it to work or wish to keep your SerializerMethodField structure, then we must add the data of those 3 fields before saving. You can either pass the data as parameter in the serializer, like so:
serializer.save(targetDefn=variable_1, roleId=variable_2, empId=variable_3)
Or you can override the create and update serializer methods to do it there, example:
def create(self, validated_data):
targetDefn = validated_data["targetDefn"]
roleId = validated_data["roleId"]
emp_id = validated_data["emp_id"]
# preprocess those data if needed
# Then create your model
Target.objects.create(targetDefn=targetDefn, ...)