Django serializer read and write multiple model field with - django

Question

How to read and write multiple models in Django rest framework Model Serializer. like I have created a user-create model view set API, for that, I create a Model Serializer. there I need to give multiple permissions. for that, I pass the user_permissions field with an array of permission's id. now, how can I define a field in the user Model Serializer that can create a user with this permission and then get the user with permission's data?
class UserSerializer(serializers.ModelSerializer):
class Meta:
model = AbstractUser
fields = "__all__"
extra_kwargs = {'password': {'write_only': True},}
extra_fields = ['user_permissions']
#view
class RegistrationView(viewsets.ModelViewSet):
serializer_class = UserSerializer
queryset = AbstractUser.objects.all()
parser_classes = (FormParser, MultiPartParser)
permission_classes_by_action = [IsAdminUser, ]
def create(self, request, *args, **kwargs):
response_data = super(RegistrationView, self).create(request,*args,**kwargs)
return Response({"data": response_data.data})
request body
{
"username": "testuser",
"email": "testuser#example.com",
"first_name": "test",
"last_name": "test",
"password": "Abcd#123456",
"user_permissions": [1, 2, 3, 4, 5]
}
required response
{
"id": 1,
"email": "testuser#example.com",
"username": "testuser",
"first_name": "test",
"last_name": "test",
"is_superuser": false,
"is_staff": false,
"is_active": true,
"date_joined": "2022-08-17T10:25:48.446821Z",
"user_permissions": [
{
"id": 1,
"name": "Can add User",
"codename": "add_user",
"content_type": "account"
},
{
"id": 2,
"name": "Can change User",
"codename": "change_user",
"content_type": "account"
},
{
"id": 3,
"name": "Can delete User",
"codename": "delete_user",
"content_type": "account"
},
{
"id": 4,
"name": "Can view User",
"codename": "view_user",
"content_type": "account"
},
{
"id": 5,
"name": "Can view log entry",
"codename": "view_logentry",
"content_type": "admin"
}
],
"groups": []
}

Answer 1

now, how can I define a field in the user Model Serializer that can create a user with this permission and then get the user with permission's data?
You can override the create() method in Serializer Class
def create(self, validated_data):
instance = super().create(validated_data) #save instance first
for permission_id in validated_data['user_permissions']:
... #do something for associate user_permission to user
return instance
I have some doubts about extra_fields = ['user_permissions'].
I think you have to add a ListField in serializer named user_permissions, in this way the serializer recognize the field, validate it and you can find the field in validated_data dictionary.