Basic Django REST framework - Write only resource - python

I am trying to create a simple service which allows anonymous users to submit their name and email. I want to AllowAny on adding their info, and IsAuthenticated on everything else. I'm having trouble getting this granularity.
models.py
from django.db import models
class Invitee(models.Model):
name = models.CharField(max_length=255)
email = models.EmailField(max_length=70,blank=True)
modified = models.DateTimeField(auto_now=True)
serializers.py
class InviteeSerializer(serializers.HyperlinkedModelSerializer):
class Meta:
model = Invitee
fields = ('name', 'email')
def create(self, validated_data):
return Invitee(**validated_data)
views.py
class InviteeViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows groups to be viewed or edited.
"""
queryset = Invitee.objects.all()
serializer_class = InviteeSerializer
What and where should I put to make it so users can submit their name and email, but only admins can read, update, delete? Thanks any help.

The easiest and safest way to do this is with multiple serializers, one of each user class you need. You will also need to use custom permissions to enforce the read/write difference between authenticated and anonymous users.
class InviteeSerializer(serializers.HyperlinkedModelSerializer):
def create(self, validated_data):
return Invitee(**validated_data)
class LimitedInviteeSerializer(InviteeSerializer):
class Meta:
model = Invitee
fields = ('name', 'email', ) # a limited subset of the fields
class FullInviteeSerializer(InviteeSerializer):
class Meta:
model = Invitee
fields = ('name', 'email', "modified", ) # all of the fields
While right now it only looks like you need read/write, if you need full read/write/delete permissions I would recommend reading this Stack Overflow question.
You will also need to control what serializer is being used on the view level. This needs to be done using a combination of permissions and overridden view methods.
class InviteeViewSet(viewsets.ModelViewSet):
"""
API endpoint that allows groups to be viewed or edited.
"""
queryset = Invitee.objects.all()
serializer_class = LimitedInviteeSerializer
def get_serializer_class(self):
if self.request.user.is_active:
return FullInviteeSerializer
return super(InviteeViewSet, self).get_serializer_class()
On the view you will need to override get_serializer_class to determine what serializer should be used based on if the user is active. Anonymous users should never be marked as active, so this is the best way to check while excluding deactivated accounts.
You will also need to create a custom permissions class that will do the opposite of the built-in IsAuthenticatedOrReadOnly permission. You are looking for authenticated users to do everything, and anonymous users to only be write-only. I've called this class IsAuthenticatedOrWriteOnly to match the other permission class.
class IsAuthenticatedOrWriteOnly(BasePermission):
"""
The request is authenticated as a user, or is a write-only request.
"""
def has_permission(self, request, view):
WRITE_METHODS = ["POST", ]
return (
request.method in WRITE_METHODS or
request.user and
request.user.is_authenticated()
)
You just need to add this your existing list of permission classes, or override it manually it on the view using permission_classes.

Related

DRF - Prevent users from referencing objects that do not belong to them

I have two models like so with a parent child relation:
models.py
class Bank(...):
user = models.ForeignKey('User', ...)
class Account(...)
bank = models.ForeignKey('Bank', ...)
user = models.ForeignKey('User', ...)
I am using DRF and want to provide API access to these models. I want to ensure that Users can only access their own data. On the viewsets I can retrict the querysets to just the objects the user "owns" like so:
views.py
class BankViewSet(...):
def get_queryset(self):
return self.queryset.filter(
user = request.user
)
And I can do the same for Accounts.
However, how can I stop a user from creating an Account via POST request with a Bank that they do not own? I want to ensure that users can only create Accounts that belong to a Bank that they own.
How can I enforce/check that the Bank in the Account POST request contains the same user as the requestor?
You can create a field-level validation on the AccountSerializer class, as
class AccountSerializer(serializers.ModelSerializer):
class Meta:
model = Account
fields = (
"bank",
"field_1",
"field_2"
)
def validate_bank(self, bank_instance: Bank):
if bank_instance.user == self.context["request"].user:
return bank_instance
raise serializers.ValidationError("Not belongs to you!!!")

How can I set permission for seperate request methods in DRF ModelViewSet?

I'm fairly new to Django and Django Rest Framework and I can't figure out why my code isn't working.
I have a Biz model that has a few fields:
class Biz(models.Model):
uuid = models.UUIDField(default=uuid.uuid4, editable=False)
title = models.CharField(max_length=200)
description = models.TextField()
address = models.CharField(max_length=255, blank=True)
city = models.CharField(max_length=100)
phone = PhoneNumberField()
which I serializer using ModelSerializer:
class BizSerializer(serializers.ModelSerializer):
class Meta:
model = Biz
fields = "__all__"
And I use ModelViewSet to have an endpoint for it:
class BizViewSet(viewsets.ModelViewSet):
queryset = Biz.objects.all()
authentication_classes = (authentication.TokenAuthentication,)
permission_classes = [HasGroupPermission]
required_groups = {
"GET": ["__all__"],
"POST": ["member", "biz_post"],
"PUT": ["member", "biz_edit"],
"PATCH": ["member", "biz_edit"],
}
serializer_class = BizSerializer
You probably noticed HasGroupPermission. It is a custom permission I made to confirm the requesting user is in required group(s) the code is:
def is_in_group(user, group_name):
"""
Takes a user and a group name, and returns `True` if the user is in that group.
"""
try:
return Group.objects.get(name=group_name).user_set.filter(id=user.id).exists()
except Group.DoesNotExist:
return None
class HasGroupPermission(permissions.BasePermission):
"""
Ensure user is in required groups.
"""
def has_permission(self, request, view):
# Get a mapping of methods -> required group.
required_groups_mapping = getattr(view, "required_groups", {})
# Determine the required groups for this particular request method.
required_groups = required_groups_mapping.get(request.method, [])
# Return True if the user has all the required groups or is staff.
return all(
[
is_in_group(request.user, group_name)
if group_name != "__all__"
else True
for group_name in required_groups
]
) or (request.user and request.user.is_staff)
However, when I make a GET request, the permission function works like it's supposed to and allows everyone to make the request, and when i make a POST request, the permission function also works perfectly (if user isn't in both "member" and "biz_post" groups the request is denied).
The problem arises when I try other methods such as PUT, PATCH, and DELETE. Why is this issue happening? Half the methods work and the other half (sorta) don't. My knowledge in DRF is limited at the moment, and I can't seem to solve the issue.
I realized my problem which I found very silly. My BizViewSet is actually a ViewSet and I didn't realize that I have to make PATCH, PUT, and DELETE requests to the object link (as in localhost:8000/api/biz/$id). Since my User serializer isn't a ViewSet I thought the patch method works the same way which was I pass a primary key in JSON along with the data I wanted to patch but ViewSets are different and I didn't know that. Silly.
Hi you can use DjangoModelPermissions instead of HasGroupPermission
(at the first you must import it)
from rest_framework.permissions import DjangoModelPermissions
This permission check that user have permission for PUT, POST and DELETE
All user have GET permission
You must set permission for user in admin or set permission for group of user
I hope it helps you
has_permission method not provide object-level permission and PUT and PATCH need object-level permission.
You must create object-level permissions, that are only run against operations that affect a particular object instance by using has_object_permission method of permissions.BasePermission class.
See this link.
Hope it helped.

Rest Framework serializers, forbid users to change others password

I'm creating a simple web app and I cannot find any way to forbid other users from changing your password. This is minimal code:
# serializers.py
from rest_framework import serializers
class UserSerializer(serializers.ModelSerializer):
def create(self, validated_data):
# have to use custom create method because default method calls `User.objects.create()` which doesn't take care of password hashing and other important stuff
return User.objects.create_user(**validated_data)
class Meta:
model = User
fields = ('id', 'username', 'email', 'password')
read_only_fields = ('id', 'username')
# password is set to write_only because I don't want to send it to anybode (even though it's just a hash)
extra_kwargs = {'password': {'write_only': True}}
# views.py
from .serializers import UserSerializer
from rest_framework import generics
from django.contrib.auth.models import User
class UserDetails(generics.RetrieveUpdateAPIView):
queryset = User.objects.all()
serializer_class = UserSerializer
I could take care of this myself by using APIView.
# views.py
from .serializers import UserSerializer
from rest_framework.views import APIView
from django.contrib.auth.models import User
class UserDetails(APIView):
def put(self, request, format=None):
serialized = UserSerializer(data=request.DATA)
if not serialized.is_valid():
return # probably HTTP 400 Error code
if request.user.id != serialized.data['id']:
# this if is what I'm trying to achieve
return # probably HTTP 403 Error code
user = User.objects.update(
id=serialized.data['id'],
email=serialized.data['email']
)
if 'password' in request.DATA:
user.set_password(request.DATA['password'])
return # probably HTTP 200 Error code
Unfortunately, that would have caused that scheme generated by rest_framework.schemas.get_schema_view would be incomplete. And I use for communication CoreAPI (which cannot communicate with something that is not described in the scheme) so I cannot do that. I haven't found anything in the official documentation.
This seems to be a too basic problem that has a super easy solution that I missed. Thanks for any ideas or places where to look.
PS: I'm using django2.1 with python3.6
Edit: osobacho's solutions is clean and works like charm. Anyway I also need to allow modifications (let's say of TODO-list) only to creator of that todo list. Thought that solution for password problem would be applicable but it's not.
You can get the user in the request. That way each user will only be able to change their own password.
class UserDetails(generics.RetrieveUpdateAPIView):
queryset = User.objects.all()
serializer_class = UserSerializer
def get_object(self):
return self.request.user
For your second question take a look at django_restframework http://www.django-rest-framework.org/api-guide/permissions/ permissions here is an example:
class IsOwnerOrReadOnly(permissions.BasePermission):
"""
Object-level permission to only allow owners of an object to edit it.
Assumes the model instance has an `owner` attribute.
"""
def has_object_permission(self, request, view, obj):
# Read permissions are allowed to any request,
# so we'll always allow GET, HEAD or OPTIONS requests.
if request.method in permissions.SAFE_METHODS:
return True
# Instance must have an attribute named `owner`.
return obj.owner == request.user
then you need to add to your view:
permission_classes = (IsOwnerOrReadOnly,)
hope it helps

Implement roles in django rest framework

I am building an API that should have the following kind of users
super_user - create/manage admins
admin - manage events(model) and event participants
participants - participate in events, invited to events by admins
Additional i want to have each type of user to have phone number field
I tried
class SuperUser(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
phone_number = models.CharField(max_length=20)
class Admin(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
phone_number = models.CharField(max_length=20)
class Participant(models.Model):
user = models.OneToOneField(User, on_delete=models.CASCADE)
phone_number = models.CharField(max_length=20)
But gut is telling me its a wrong way to handle this. Can someone please help.
One possible solution is:
Have only one User Model with role field, which defines what user role is.
Create a User Group and add each group needed permissions.
Add User to User Group
Limit access using a Django REST Framework (later DRF) Permission Class.
Explanation:
Using only one user model is a more simple and flexible solution. You can query all users, or filtered by feature (like user role). Standart Django auth system expects one UserModel.
Read more about Django user groups. See "Django Permissions Docs #1" and "Django Groups Docs #2". Also useful is "User groups and permissions".
You need to create a group for each user role, and add needed permissions for each group. (Django has a default model permission, created automatically, look at the docs on the given links) or create the needed permission manually in the model definition.
Manually or using a script, add User to the needed group by defining his role when a user is created or manually by Django Admin interface.
Now everything should be ready for limited access by the user's role. You can easily limit access to the DRF View using a permission class. See more information in the "DRF Permission Docs".
Let's define our own:
from rest_framework.permissions import DjangoModelPermissions
# Using DjangoModelPermissions we can limit access by checking user permissions.
# Rights need only for CreateUpdateDelete actions.
class CUDModelPermissions(DjangoModelPermissions):
perms_map = {
'GET': [],
'OPTIONS': [],
'HEAD': ['%(app_label)s.read_%(model_name)s'],
'POST': ['%(app_label)s.add_%(model_name)s'],
'PUT': ['%(app_label)s.change_%(model_name)s'],
'PATCH': ['%(app_label)s.change_%(model_name)s'],
'DELETE': ['%(app_label)s.delete_%(model_name)s'],
}
# Or you can inherit from BasePermission class and define your own rule for access
from rest_framework.permissions import BasePermission
class AdminsPermissions(BasePermission):
allowed_user_roles = (User.SUPERVISOR, User.ADMINISTRATOR)
def has_permission(self, request, view):
is_allowed_user = request.user.role in self.allowed_user_roles
return is_allowed_user
# ----
# on views.py
from rest_framework import generics
from .mypermissions import CUDModelPermissions, AdminsPermissions
class MyViewWithPermissions(generics.RetrieveUpdateDestroyAPIView):
permission_classes = [CUDModelPermissions, ]
queryset = SomeModel.objects.all()
serializer_class = MyModelSerializer
You can add additional permission class to combine access limitation.
So in Django any user has a flag is_superuser that corresponds to your 'superuser'. So just use that - e.g. User.objects.create(is_superuser=True).
For the rest you can simply use a field for a normal User model to differentiate between subroles of a normal user.
class User(AbstractBaseUser):
can_participate_event = models.Boolean(default=False)
can_create_event = models.Boolean(default=False)
Or
class User(AbstractBaseUser):
permissions = models.CharField(default='') # and populate with e.g. 'create_event,participate_event'
Still you will need to check all those fields in your view probably. The more you add to your application, the hairier this becomes so I would suggest using a 3rd party library like rest-framework-roles (I'm the author) or guardian.

Adding IsAuthenticatedOrReadOnly permission in django rest framework

Suppose I have the following model -
class Person(models.Model):
name = models.CharField(max_length=200)
clubs = models.ManyToManyField(Club,related_name = 'people')
date = models.DateTimeField(default=datetime.now)
def __str__(self):
return self.name
used to create a rest api.
views.py
class PersonDetail(generics.RetrieveUpdateDestroyAPIView):
serializer_class = PersonSerializer
def get_object(self):
person_id = self.kwargs.get('pk',None)
return Person.objects.get(pk=person_id)
How do I add permissions so that only authenticated user can add,update delete or retrieve objects from the person list in the api. And read-only permissions for non authorized users. I tried going through the docs but it is all very confusing. Can someone explain?
You need to add IsAuthenticatedOrReadOnly permission class to PersonDetail view.
From the DRF Docs:
The IsAuthenticatedOrReadOnly will allow authenticated users to perform any request. Requests for unauthorised users will only be permitted if the request
method is one of the "safe" methods; GET, HEAD or OPTIONS.
from rest_framework.permissions import IsAuthenticatedOrReadOnly
class PersonDetail(generics.RetrieveUpdateDestroyAPIView):
serializer_class = PersonSerializer
permission_classes = (IsAuthenticatedOrReadOnly,) # specify the permission class in your view
def get_object(self):
person_id = self.kwargs.get('pk',None)
return Person.objects.get(pk=person_id)

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