integrate django password validators with django rest framework validate_password

Solution 1:

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)

Solution 2:

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

Solution 3:

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