User creation with unique constraint in Django Rest framework - django

Question

I researched about it in Google, and have tried in lot of ways but still not able to get it right. Here are the requirements:
A one to one field for extending User model, so this has been achieved and the new model is called Customer.
Now, with new user 201 response is returned BUT not all the data is serialized, only date_of_birth is coming in json format, I want even the User to be in that json response.
If I try to add a user with a username which already exists it plays up really bad. I am trying with Try and Except but it really doesnt work. I want a response of 409 conflict to be sent if the username already exists.
Here is UserSerializer.py:
-
from django.contrib.auth.models import User
from rest_framework import serializers
class UserSerializer(serializers.HyperlinkedModelSerializer):
new_username = serializers.SerializerMethodField()
class Meta:
model = User
fields = ('url', 'pk', 'username', 'email', 'is_staff', 'new_username')
extra_kwargs = {
'username': {'validators': []},
}
def get_new_username(self, obj):
return obj.username
Here is Customer model:
from django.db import models
from django.contrib.auth.models import User
class Customer(models.Model):
user = models.OneToOneField(User, related_name="customer", on_delete=models.CASCADE)
date_of_birth = models.DateField(max_length=8)
def __unicode__(self):
return u'%s' % self.user.username
Here is CustomerSerializer class:
from django.contrib.auth.models import User
from django.contrib.auth import get_user_model
from rest_framework import serializers, status
from rest_framework.response import Response
from customers.models import Customer
from api.serializers import UserSerializer
class CustomerSerializer(serializers.HyperlinkedModelSerializer):
user = UserSerializer()
class Meta:
model = Customer
fields = ('url', 'date_of_birth', 'user')
def create(self, validated_data):
print "coming inside serializer create"
user_data = validated_data.pop("user")
print user_data
try:
userinstance = User.objects.get_or_create(**user_data)[0]
print "user..."
print userinstance
print validated_data
customer = Customer.objects.create(user=userinstance, **validated_data)
print customer.user
return customer
except Exception as exception:
print exception
# print "customer --> %s " % customer
return customer
def update(self, instance, validated_data):
print "coming inside update"
user_data = validated_data.pop("user")
username = user_data.pop('username')
user = get_user_model().objects.get_or_create(username=username)[0]
user.username = username
user.email = user_data.get('email', user.email)
user.save()
# instance.user = user
instance.date_of_birth = validated_data.get('date_of_birth', instance.date_of_birth)
instance.save()
And here is view set for Customer:
from rest_framework import viewsets
from customers.models import Customer
from customers.serializers import CustomerSerializer
from api.permissions import IsOwnerOrAdmin
from rest_framework import authentication, permissions, status
from rest_framework.response import Response
class CustomerViewSet(viewsets.ModelViewSet):
serializer_class = CustomerSerializer
queryset = Customer.objects.all()
authentication_classes = (authentication.TokenAuthentication,
authentication.SessionAuthentication,
authentication.SessionAuthentication, )
def get_permissions(self):
if self.action == 'list':
self.permission_classes = (permissions.IsAdminUser,)
elif self.action == 'create':
self.permission_classes = (permissions.AllowAny,)
return super(self.__class__, self).get_permissions()
def create(self, request, *args, **kwargs):
print "This is view create -----------------------------"
serializer = self.get_serializer(data=request.data)
# print serializer
if serializer.is_valid(): # It passes because here there are no new objects created yet
print "serializer is valid ......"
# self.pre_save(serializer.object)
# user_data = serializer.validated_data.get("user")
# print user_data
self.object = serializer.create(serializer.validated_data) # It creates the User (triggering the signal) instance and then when saving UserProfile, it give the integrity error
# self.post_save(self.object, created=True)
# headers = self.get_success_headers(serializer.data)
print 'coming here ....1'
print self.object
return Response(serializer.validated_data, status=status.HTTP_201_CREATED)
print 'coming here..'
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
So, basically I would like to create new customers with all data returned as response and status 201 and if username already exists, then 409 or status code which I define and the some data which DRF should not complaint about i.e; right now it says that OrderDict does not contain PK if I modify the serializer.
Thanks
Edit 1
Here is updated serilizer with custom exception:
from django.contrib.auth.models import User
from django.contrib.auth import get_user_model
from django.db import IntegrityError
from rest_framework import serializers, status
from rest_framework.response import Response
from rest_framework.exceptions import APIException
from customers.models import Customer
from api.serializers import UserSerializer
class CustomerSerializer(serializers.HyperlinkedModelSerializer):
user = UserSerializer()
class Meta:
model = Customer
fields = ('url', 'pk', 'date_of_birth', 'user')
def create(self, validated_data):
print "coming inside serializer create"
user_data = validated_data.pop("user")
print user_data
try:
userinstance = User.objects.create_user(**user_data)
print "user..."
print userinstance
print validated_data
customer = Customer.objects.create(user=userinstance, **validated_data)
print customer.user
return customer
# except TypeError as exception:
# print exception
# # print "customer --> %s " % customer
# raise TypeError(exception)
except IntegrityError as exception:
raise Custom409(exception)
def update(self, instance, validated_data):
print "coming inside update"
user_data = validated_data.pop("user")
username = user_data.pop('username')
user = get_user_model().objects.get_or_create(username=username)[0]
user.username = username
user.email = user_data.get('email', user.email)
user.save()
# instance.user = user
instance.date_of_birth = validated_data.get('date_of_birth', instance.date_of_birth)
instance.save()
return instance
class Custom409(APIException):
status_code = status.HTTP_409_CONFLICT
default_detail = "User already there."
But still get :
Traceback (most recent call last):
File "/home/naveen/projects/gratis/customers/tests.py", line 37, in test_if_anyone_could_create_customers
format='json')
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/test.py", line 299, in post
path, data=data, format=format, content_type=content_type, **extra)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/test.py", line 221, in post
return self.generic('POST', path, data, content_type, **extra)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/django/test/client.py", line 379, in generic
return self.request(**r)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/test.py", line 288, in request
return super(APIClient, self).request(**kwargs)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/test.py", line 240, in request
request = super(APIRequestFactory, self).request(**kwargs)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/django/test/client.py", line 466, in request
six.reraise(*exc_info)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
return view_func(*args, **kwargs)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/viewsets.py", line 83, in view
return self.dispatch(request, *args, **kwargs)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/views.py", line 477, in dispatch
response = self.handle_exception(exc)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/views.py", line 437, in handle_exception
self.raise_uncaught_exception(exc)
File "/home/naveen/.virtualenvs/gratis/local/lib/python2.7/site-packages/rest_framework/views.py", line 448, in raise_uncaught_exception
raise exc
IntegrityError: duplicate key value violates unique constraint "auth_user_username_key"
DETAIL: Key (username)=(user2) already exists.
And also the test case is as follows:
def test_if_anyone_could_create_customers(self):
create_user = self.client.post('/api/customers/',
{'user':{'username': 'user2', 'email': 'user2#gmail.com'}, 'date_of_birth':"1982-10-20"},
format='json')
print create_user
self.assertEqual(create_user.status_code, 201)
create_user = self.client.post('/api/customers/',
{'user': {'username': 'user2', 'email': 'user2#gmail.com'},'date_of_birth': "1982-10-20"},
format='json')
print create_user
# no duplicates
user = User.objects.all()
print user
self.assertEqual(create_user.status_code, 409)

Answer 1

This is because you are catching exceptions far too broadly in your create method. In fact you should never do this (regardless of whether you use DRF or not)
except Exception as exception:
print exception
# print "customer --> %s " % customer
return customer
You should only catch the specific exceptions that you need to catch. And you shouldn't be returning a customer at all. In this case, examination of ModelSerializer tells us that the only one you really should catch is TypeError. Even that is raised again for the caller to handler.
except TypeError as exception:
print exception
# print "customer --> %s " % customer
raise TypeError(exception)
Now you should get what you want but according to your comments, you are not so try raising a custom error.
from rest_framework.exceptions import APIException
from django.utils.encoding import force_text
class Custom409(APIException):
status_code = status.HTTP_409_CONFLICT
default_detail = 'A conflict occurred'
And then
except IntergrityError as ext:
print exception
# print "customer --> %s " % customer
raise Custom409(ext)

Answer 2

The your code is raising IntegrityErorr because you are violated unique constraint while creating profile.
You should use get_or_create while creating user profile/customer instance. Something like this should work.
# CustomerSerializer
def create(self, validated_data):
"""...snip..."""
try:
userinstance = User.objects.get_or_create(**user_data)[0]
customer = Customer.objects.get_or_create(
user=userinstance, defaults=validated_data)[0]
return customer
except Exception as exception:
# custom validationerror
raise ConflictError({"user": "User already exists"})

Answer 3

Maybe you should try to catch it in your view directly:
views.py
from rest_framework import viewsets
from customers.models import Customer
from customers.serializers import CustomerSerializer
from api.permissions import IsOwnerOrAdmin
from rest_framework import authentication, permissions, status
from rest_framework.response import Response
class CustomerViewSet(viewsets.ModelViewSet):
serializer_class = CustomerSerializer
queryset = Customer.objects.all()
authentication_classes = (authentication.TokenAuthentication,
authentication.SessionAuthentication,
authentication.SessionAuthentication, )
def get_permissions(self):
if self.action == 'list':
self.permission_classes = (permissions.IsAdminUser,)
elif self.action == 'create':
self.permission_classes = (permissions.AllowAny,)
return super(self.__class__, self).get_permissions()
def create(self, request, *args, **kwargs):
print "This is view create -----------------------------"
serializer = self.get_serializer(data=request.data)
# print serializer
try:
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
except ValidationError as e:
if e.detail.get('username') == ['user with this username already exists.']:
raise Custom409()
return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
And removing the logic you put in the serializer create. DRF exceptions are meant to be used in views not serializer.