Django Rest Framework - to_internal_value Error Inconsistency - python-3.x

Question

I have a model, User, in which the primary unique field is email. I have a separate Organization model which allows users to map to organizations through a many-to-many mapping.
I want the serializer to allow users to be created if they have an existing email but no organization association (organization is taken from the user making the request so is not in the payload).
The standard ModelSerializer includes a check against the field in to_internal_value(). I am consequently trying to override it like so:
def to_internal_value(self, data):
"""
Dict of native values <- Dict of primitive datatypes.
"""
fields = self._writable_fields
for field in fields:
validate_method = getattr(self, 'validate_' + field.field_name, None)
primitive_value = field.get_value(data)
try:
if validate_method == self.validate_email:
if User.objects.filter(email=primitive_value).exists():
if not self.active_organization.members.filter(email=primitive_value).exists():
continue
else:
validated_value = field.run_validation(primitive_value)
if validate_method is not None:
validated_value = validate_method(validated_value)
except ValidationError as exc:
errors[field.field_name] = exc.detail
except DjangoValidationError as exc:
errors[field.field_name] = get_error_detail(exc)
except SkipField:
pass
else:
set_value(ret, field.source_attrs, validated_value)
return super().to_internal_value(data)
This works, but the error that is returned if the object already has a record in User and Organization does not correctly map as a dictionary. For example, the validation error shows this:
[ErrorDetail(string='User with this Email already exists.', code='unique')]
Instead of what it should show, this:
{'email': [ErrorDetail(string='User with this Email already exists.', code='unique')]}
I tested by overriding the method and trying both my custom called code vs. the original, and it replicates the above findings:
def to_internal_value(self, data):
"""
Dict of native values <- Dict of primitive datatypes.
"""
try:
print('trying custom')
for field in self._writable_fields:
if field.field_name == 'email':
print(field.run_validation)
validated_value = field.run_validation(field.get_value(data))
except Exception as e:
print('error custom')
print(str(e))
try:
print('Trying original')
value = super().to_internal_value(data)
except Exception as e:
print('Exception - original')
print(str(e))
Output:
trying custom
<bound method CharField.run_validation of EmailField(max_length=254, validators=[<UniqueValidator(queryset=User.objects.all())>])>
error custom
[ErrorDetail(string='User with this Email already exists.', code='unique')]
Trying original
Exception - original
{'email': [ErrorDetail(string='User with this Email already exists.', code='unique')]}
Can anyone help me understand why this is happening please? I'm really stuck as to how this is happening.

Answer 1

I was not able to figure out why exactly the errors generated by to_internal_value(self, data) change when I copy the code from the underlying ModelSerializer vs calling super(). However, I did find a kind-of hackish workaround.
Because I strip out all the other related info (nested serializers, kind of) before hand, I'm really just worried about the email. Therefore, I traverse the _writable_fields twice: the first time I look for an existing email where it isn't in the organization. If those conditions are true, I return a dictionary and proceed to the create() method. If they fail, I call super. So far this seems to work. Here is my simplified class.
def to_internal_value(self, data):
"""
Dict of native values <- Dict of primitive datatypes.
"""
try:
for field in self._writable_fields:
if field.field_name == 'email':
primitive_value = field.get_value(data)
validator = EmailValidator()
validator(primitive_value)
if User.objects.filter(email=primitive_value).exists():
if not self.active_organization.members.filter(email=primitive_value).exists():
self.email_already_exists = True
return {'email': primitive_value}
except:
pass
return super().to_internal_value(data)
For reference, this is the complete ViewSet and Serializer I'm using:
class AdminUsersSerializer(serializers.ModelSerializer):
"""User serializer for the admin user view"""
groups = GenericGroupSerializer(source='group_set', many=True, required=False)
permission_sets = GenericPermissionSetSerializer(source='permissionset_set', many=True, required=False)
active_organization = None
email_already_exists = False
class Meta:
model = User
fields = ['pk', 'email', 'groups', 'permission_sets'] # , 'permissions']
def set_active_organization(self, organization):
self.active_organization = organization
def create(self, validated_data):
if not self.email_already_exists:
user = User.objects.create(
email=validated_data['email']
)
user.set_password(None)
user.save()
else:
user = User.objects.get(email=validated_data['email'])
return user
def to_internal_value(self, data):
"""
Dict of native values <- Dict of primitive datatypes.
"""
try:
for field in self._writable_fields:
if field.field_name == 'email':
primitive_value = field.get_value(data)
validator = EmailValidator()
validator(primitive_value)
if User.objects.filter(email=primitive_value).exists():
if not self.active_organization.members.filter(email=primitive_value).exists():
self.email_already_exists = True
return {'email': primitive_value}
except:
pass
return super().to_internal_value(data)
class AdminUsersViewSet(viewsets.ModelViewSet):
queryset = User.objects.all()
serializer_class = AdminUsersSerializer
permission_classes = [account_permissions.IsAdminRequired]
http_method_names = ['get', 'post']
active_organization = None
def create(self, request, *args, **kwargs):
self.active_organization = self.request.user.activeorganization.organization
groups = None
permission_sets = None
serializer = self.get_serializer(data=request.data)
serializer.set_active_organization(self.active_organization)
if 'groups' in serializer.initial_data:
if serializer.initial_data.get('groups'):
groups = serializer.initial_data.pop('groups')
else:
serializer.initial_data.pop('groups')
if 'permission_sets' in serializer.initial_data:
if serializer.initial_data.get('permission_sets'):
permission_sets = serializer.initial_data.pop('permission_sets')
else:
serializer.initial_data.pop('permission_sets')
# Normal method functions
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
headers = self.get_success_headers(serializer.data)
# Created user
user = User.objects.get(email=serializer.data['email'])
# Add user to organization
self.active_organization.members.add(user)
# Make sure to format the ajax groups data properly
if groups:
try:
group = Group.objects.get(
id=groups,
organization=self.active_organization
)
group.members.add(user)
except:
pass
if permission_sets:
try:
permission_set = PermissionSet.objects.get(
id=permission_sets,
organization=self.active_organization
)
permission_set.members.add(user)
except:
pass
return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
def get_queryset(self):
return self.queryset.filter(
userorganizationmembership__organization=self.request.user.activeorganization.organization
).all()
It does feel hackish, but it seems to be getting the job done.