integrate django password validators with django rest framework validate_password

Question

I\'m trying to integrate django validators 1.9 with django rest framework serializers. But the serialized \'user\' (of django rest framework) is not compatible with the djan

Answer 1

Use Serializers! Have a validate_fieldname method!

class UserSerializer(serializers.ModelSerializer):

    class Meta:
        model = User
        fields = (
            'id', 'username', 'password', 'first_name', 'last_name', 'email'
        )
        extra_kwargs = {
            'password': {'write_only': True},
            'username': {'read_only': True}
        }

    def validate_password(self, value):
        try:
            validate_password(value)
        except ValidationError as exc:
            raise serializers.ValidationError(str(exc))
        return value

    def create(self, validated_data):
        user = super().create(validated_data)
        user.set_password(validated_data['password'])

        user.is_active = False
        user.save()
        return user

    def update(self, instance, validated_data):
        user = super().update(instance, validated_data)
        if 'password' in validated_data:
            user.set_password(validated_data['password'])
            user.save()
        return user

Answer 2

At the time of creating new user(registration) then self.instance will be none, it will work when your are resting the password, change password or updating user data with password. But if you want to check the password should not be similar to your email or username then you need to include "SequenceMatcher" in your validation

data = self.get_initial()
username = data.get("username")
email = data.get("email")
password = data.get("password") 
max_similarity = 0.7
if SequenceMatcher(a=password.lower(), b=username.lower()).quick_ratio() > max_similarity:
    raise serializers.ValidationError("The password is too similar to the username.")
if SequenceMatcher(a=password.lower(), b=email.lower()).quick_ratio() > max_similarity:
    raise serializers.ValidationError("The password is too similar to the email.")

Answer 3

You can access the user object through self.instance on the serializer object, even when doing field-level validation. Something like this should work:

 from django.contrib.auth import password_validation

 def validate_password(self, value):
    password_validation.validate_password(value, self.instance)
    return value

Answer 4

Like you mentioned, when you validate the password in validate_password method using UserAttributeSimilarityValidator validator, you don't have the user object.

What I suggest that instead of doing field-level validation, you shall perform object-level validation by implementing validate method on the serializer:

import sys
from django.core import exceptions
import django.contrib.auth.password_validation as validators

class RegisterUserSerializer(serializers.ModelSerializer):

     # rest of the code

     def validate(self, data):
         # here data has all the fields which have validated values
         # so we can create a User instance out of it
         user = User(**data)

         # get the password from the data
         password = data.get('password')

         errors = dict() 
         try:
             # validate the password and catch the exception
             validators.validate_password(password=password, user=User)

         # the exception raised here is different than serializers.ValidationError
         except exceptions.ValidationError as e:
             errors['password'] = list(e.messages)

         if errors:
             raise serializers.ValidationError(errors)

         return super(RegisterUserSerializer, self).validate(data)