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The serializer field might be named incorrectly and not match any attribute or key on the `QuerySet` instance

I am using Django Rest and my request parameter contains:
[
{
"job_role": 2,
"technology": 1
},
{
"job_role": 1,
"technology": 1
},
{
"job_role": 2,
"technology": 1
}
]
My models are:
class Technology(models.Model):
name = models.CharField(max_length=50)
def __str__(self):
return self.name
class JobRole(models.Model):
role_name = models.CharField(max_length=100)
def __str__(self):
return self.role_name
class ExpertPricing(models.Model):
role_name = models.OneToOneField(JobRole, related_name="role", on_delete=models.SET_NULL, null=True)
experience_in_years = models.PositiveBigIntegerField()
technology = models.OneToOneField(Technology, related_name="technology", on_delete=models.SET_NULL, null=True)
salary_per_month = models.PositiveBigIntegerField()
My view looks like this:
class PricingView(APIView):
def post(self, request):
datas = request.data
data_list = []
for data in datas:
job_role_id = data["job_role"]
technology_id = data["technology"]
job_role = JobRole.objects.get(pk=job_role_id)
technology = Technology.objects.get(pk=technology_id)
expert_pricing = ExpertPricing.objects.filter(role_name=job_role, technology=technology)
if expert_pricing:
data_list.append(expert_pricing)
serializer = ExpertPricingSerializer(data_list, many=True)
return Response(serializer.data, status=status.HTTP_200_OK)
serializers.py
class TechnologySerializer(serializers.ModelSerializer):
class Meta:
model = Technology
fields = ("id", "name")
class JobRoleSerializer(serializers.ModelSerializer):
class Meta:
model = JobRole
fields = ("id","role_name")
class ExpertPricingSerializer(serializers.ModelSerializer):
role = JobRoleSerializer(many=False, read_only=True)
technology = TechnologySerializer(many=False, read_only=True)
class Meta:
model = ExpertPricing
fields = "__all__"
I am unable to understand why data_list is not being serialized.
the error says:
AttributeError: Got AttributeError when attempting to get a value for field `experience_in_years` on serializer `ExpertPricingSerializer`.
The serializer field might be named incorrectly and not match any attribute or key on the `QuerySet` instance.
Original exception text was: 'QuerySet' object has no attribute 'experience_in_years'.

Since you defined in your model that those two fields (experience_in_years and salary_per_month) can not be empty, it seems like you need to do one of these things:
Send experience_in_years and salary_per_month fields in your request too.
Give a default value to those fields
Make it null=True, blank=True
If you do 2 or 3 those solutions require migration, keep that in mind, after doing one of those things you should be good to go

Django ManyToMany field as json format

I'm trying to get data as json format. I've one ManyToMany field which is returning just id. But I need that contents too. Here is my models.py
class Pricing(models.Model):
name = models.CharField(max_length = 100)
price = models.CharField(max_length = 100)
def __str__(self):
return self.name+' and '+self.price
class Service(models.Model):
name = models.CharField(max_length=100)
price = models.ManyToManyField(Pricing, blank=True)
def __str__(self):
return self.name
And also the views.py which is returning json format data
def all_service_json(request, name):
data = serializers.serialize("json", Service.objects.filter(name__icontains=name))
return HttpResponse(data)
Now Getting the output like below
[
{
"model": "myapp.service",
"pk": 2,
"fields":
{
"name": "Service name",
"price": [1, 2]
}
}
]
But want like below
[
{
"model": "myapp.service",
"pk": 2,
"fields":
{
"name": "Service name",
"price":
{
1: "Price 1",
2: "Price 2"
}
}
}
]

Creating ModelSerializer objects from within Django Rest Framework will let you display nested object data:
http://www.django-rest-framework.org/api-guide/serializers/#dealing-with-nested-objects
# myapp/serializers.py
...
from rest_framework import serializers
class PricingSerializer(serializers.ModelSerializer):
class Meta:
fields = '__all__'
model = Pricing
class ServiceSerializer(serializers.ModelSerializer):
price = PricingSerializer(read_only=True, many=True)
class Meta:
fields = '__all__'
model = Service
# myapp/views.py
def all_service_json(request, name):
services = Service.objects.filter(name__icontains=name)
data = ServiceSerializer(services, many=True).data
return HttpResponse(data)

As #robert mentioned using nested serializers will fix your issue.
But note that by default nested serializers are read-only. So If you
want to support write operations to a nested serializer field you'll
need to add create() and/or update() methods in order to explicitly
specify how the child relationships should be saved.
Writable Service Serializer
class ServiceSerializer(serializers.ModelSerializer):
price = PricingSerializer(many=True)
class Meta:
fields = '__all__'
model = Service
# sample create
def create(self, validated_data):
prices_data = validated_data.pop('price')
service = Service.objects.create(**validated_data)
for price_data in prices_data:
Price.objects.create(service=service, **price_data)
return service
# add update here
myapp/views.py
def all_service_json(request, name):
services = Service.objects.filter(name__icontains=name)
serializer = ServiceSerializer(services)
return HttpResponse(serializer.data)

So in your case all you have to do is to add depth = 1 and you will get nested representations.
Docs
The default ModelSerializer uses primary keys for relationships, but
you can also easily generate nested representations using the depth
option:
class AccountSerializer(serializers.ModelSerializer):
class Meta:
model = Account
fields = ['id', 'account_name', 'users', 'created']
depth = 1

I just start learning Django from last 8 hours and I stuck into this situation where many to many relationship is returning id instead of child data. I wrote some custom code. For me it solve my problem, hope this helps someone.
from django.core.serializers import serialize
import json
def modelToDict(model):
jsn = serialize("json", model) # convert to json
mydict = json.loads(jsn) # again convert to dictionary
return mydict
def all_service_json(request, name):
data = Service.objects.filter(name__icontains=name)
dictdata = modelToDict(data)
for i in range(len(dictdata)):
price = modelToDict(data[i].price.all())
dictdata[i]['fields']['price'] = price
return HttpResponse(json.dumps(`dictdata`), content_type="application/json")

Unable in getting data from list containing many objects

I am trying request.data.get('student_name') but it says that list has no attribute get. I just want to get the name of all students before passing to the serializer. I am sending the POST request data in the form of
[
{"student_name": "jack", "last_name": "cale", "fathers_name":"carlos"},
{"student_name": "alex", "last_name": "magasa", "fathers_name":"greg"},
{"student_name": "sia", "last_name": "gunns", "fathers_name":"brett"},
{"student_name": "jacob", "last_name": "woods", "fathers_name":"john"}
]
my views.py
#api_view(['POST'])
def add_students(request):
student_name = request.data.get('student_name')
fathers_name = request.data.get('fathers_name')
serializer = StudentsSerializer(data=request.data, many=True)
if serializer.is_valid():
serializer.save()
return Response("success")
else:
return Response(serializer.errors)
my serializers.py
class StudentsSerializer(serializers.ModelSerializer):
class Meta:
model = Students
fields = ('student_name', 'last_name', 'fathers_name')
my models.py
class Students(models.Model):
student_name = models.CharField(max_length=100, null=True)
last_name = models.CharField(max_length=100, null=True)
fathers_name = models.CharField(max_length=100, null=True)

You are trying to get value from list so you have to iterate through list
for data in request.data:
student_name = data.get('student_name')
father_name = data.get('father_name')

This seems like a question about the format of the request object. My two cents is that it's worth throwing in an import ipdb; ipdb.set_trace() at the beginning of the method, and then using print and dir to get an idea of what the object looks like. Since Django has so many django-specific objects, this helps in a lot of cases.

How to define a nested list in django for json response

I am new to Django and so I thought of creating basic app that represents operations in a shipping company. I have a WorkOrder which contains Shipments. So my models.py contains the following :
class WorkOrder (models.Model):
status = models.CharField(max_length=300,default = "New")
source = models.CharField(max_length=300)
destination = models.CharField(max_length=
material = models.CharField(max_length=300)
shipmentlist = [] //PROBLEMATIC CODE
class Shipment (models.Model):
expected_startDate = models.DateTimeField(default=timezone.now)
expected_endDate = models.DateTimeField(default=timezone.now)
shipment_status = models.CharField(max_length=300,default = "Not Started")
I have 2 serializers WorkOrderSerializer and ShipmentSerializer which i have defined in serialzers.py. I want to return a list of shipment contained within a Work Order object.
class WorkOrderSerializer
generated_date = models.DateTimeField(default=timezone.now)
status = models.CharField(max_length=300, default="New")
source = models.CharField(max_length=300)
destination = models.CharField(max_length=300)
material = models.CharField(max_length=300)
shipmentlist = ShipmentSerializer(many=True)
class ShipmentSerializer
expected_startDate = models.DateTimeField(default=timezone.now)
expected_endDate = models.DateTimeField(default=timezone.now)
shipment_status = models.CharField(max_length=300, default="Not Started")
I am following the model specified here.
http://www.django-rest-framework.org/api-guide/serializers/#dealing-with-nested-objects
In my views.py I am calling the serializer when I get the request like this
def workorder_operations(request,workorder_pk):
workorder = Work_Order.objects.filter(pk=workorder_pk)
serializer = Work_Order_Serializer(workorder)
What this produces is a json that looks like the following
{
"shipmentlist":[]
}
I am completely confused about two things :
why it shows ONLY shipment object and not the others even if it cannot parse the data or something.
why doesn't shipment get populated.
When I used the ModelSerializer instead and defined the serializer this way it all worked perfectly fine:
class ShipmentSerializer(serializers.ModelSerializer):
class Meta:
model = Shipment
fields =('expected_startDate','expected_endDate','shipment_status')
class WorkOrderSerializer(serializers.ModelSerializer):
class Meta:
model = WorkOrder
fields =('request_id','generated_date','status', 'source','destination','material')
What I want to know is how do I represent a nested list of objects so that they can be serialized properly.
I want my json for a WorkOrder object to look something like this: (Note: the variable names in the json and models might have a mismatch so please overlook that as I have stripped some of the variables to not complicate the example here.)
{
"id": "WO20170912",
"source": "BBSR",
"destination": "RKL",
"customer_id": 1,
"material": "Granite",
"weight": 19,
"status": "ALLOCATED",
"shipments": [
{
"id":"SH01234",
"work_order_id": "WO20170912",
"source": "BBSR",
"destination": "RKL"
},
{
"id":"SH01255",
"work_order_id": "WO20170912",
"source": "BBSR",
"destination": "RKL"
}
]
}

Add a ManyToManyField in WorkOrder model,
class Shipment (models.Model):
expected_startDate = models.DateTimeField(default=timezone.now)
expected_endDate = models.DateTimeField(default=timezone.now)
shipment_status = models.CharField(max_length=300,default = "Not Started")
class WorkOrder (models.Model):
status = models.CharField(max_length=300,default = "New")
source = models.CharField(max_length=300)
destination = models.CharField(max_length=
material = models.CharField(max_length=300)
shipments = models.ManyToManyField(Shipment, related_name='shipments')
Serializers would be like,
class ShipmentSerializer(serializers.ModelSerializer):
class Meta:
model = Shipment
fields = [f.name for f in model._meta.fields]
class WorkOrderSerializer(serializers.ModelSerializer):
shipments = ShipmentSerializer(many=True)
class Meta:
model = WorkOrder
fields = [f.name for f in model._meta.fields] + ['shipments']

In Django Rest, not able to serialize object which has One-to-Many mapping

I am beginner in Django Rest framework. I want to implement One to Many object mapping like following json schema:
{
"from_date": "2017-08-06T12:30",
"to_date": "2017-08-06T12:30",
"coupon_name": "WELCOME100",
"min_booking_value": 150,
"applicable_days": [
{
"from_time": "13:00",
"to_time": "15:00",
"applicable_day": 2
},
{
"from_time": "16:00",
"to_time": "18:00",
"applicable_day": 3
}
]
}
For above json schema, I have created following Django Model classes:
class Coupon(models.Model):
coupon_id = models.AutoField(primary_key=True)
from_date = models.DateTimeField()
to_date = models.DateTimeField()
coupon_name = models.TextField()
min_booking_value = models.FloatField()
def __unicode__(self):
return 'Coupon id: ' + str(self.coupon_id)
class CouponApplicableDays(models.Model):
from_time = models.TimeField()
to_time = models.TimeField()
applicable_day = models.IntegerField()
And following serializer class above models:
class CouponApplicableDaysSerializer(serializers.ModelSerializer):
class Meta:
model = CouponApplicableDays
fields = ('from_time', 'to_time', 'applicable_day')
class CouponSerializer(serializers.ModelSerializer):
coupon_applicable_days = CouponApplicableDaysSerializer(required=True, many=True)
class Meta:
model = Coupon
fields = ('coupon_id', 'from_date', 'to_date', 'coupon_name', 'min_booking_value', 'coupon_applicable_days',)
def create(self, validated_data):
coupon_applicable_days_data = validated_data.pop("coupon_applicable_days")
coupon = Coupon.objects.create(**validated_data)
CouponApplicableDays.objects.create(coupon=coupon, **coupon_applicable_days_data)
return coupon
When I save data using coupon-serializer. It saves only in Coupon table not in CouponApplicableDays.
I know, I have messed up somewhere but I don't know where. Can you guys please look into above code and tell me how can I solve this?

You have a list here
coupon_applicable_days_data = validated_data.pop("coupon_applicable_days")
Either iterate over the list and create the objects, like this:
for applicable_day in coupon_applicable_days_data:
CouponApplicableDays.objects.create(coupon=coupon, **applicable_day)
or use the bulk_create method
https://docs.djangoproject.com/en/1.11/ref/models/querysets/#bulk-create
CouponApplicableDays.objects.bulk_create(
[CouponApplicableDays(coupon=coupon, **aplicable_day)
for applicable_day in coupon_applicable_days_data]
)
Be aware that the bulk_create will not trigger pre_save/post_save signals.