Django choice fields cannot be blank, even if field is not required -- graphene-django 2.1.0 / graphql-core 2.1 regression

[picturedots]

This seems to be a regression in the upgrade of graphql-core to 2.1 together withj graphene-django to 2.1.0.

Prior to the upgrade, I could create an optional choice field in Django, and could query the value if the value of the choice field was blank.

For example, assume that I have a Django model MyModel with an optional choice field my_choices_field, and a query handler that would accept a query like

{
  myModel(id: 1) {
    id
    myChoicesField
  }
}

With the updated versions, if the value of my_choices_field is blank, this query throws a handled exception like:

 Traceback (most recent call last):
   File "/usr/local/lib/python3.7/site-packages/promise/promise.py", line 65, in try_catch
     return (handler(*args, **kwargs), None)
   File "/usr/local/lib/python3.7/site-packages/graphql/execution/executor.py", line 527, in <lambda>
     exe_context, return_type, field_asts, info, path, resolved
   File "/usr/local/lib/python3.7/site-packages/graphql/execution/executor.py", line 556, in complete_value
     return complete_leaf_value(return_type, path, result)
   File "/usr/local/lib/python3.7/site-packages/graphql/execution/executor.py", line 622, in complete_leaf_value
     path=path,
 graphql.error.base.GraphQLError: Expected a value of type "MyModelMyChoicesField" but received:

And the output of the query includes errors when the value of the field is blank:

{
  "errors": [
    {
      "message": "Expected a value of type \"MyModelMyChoicesField\" but received: ",
      "path": [
        "myModel",
        "myChoicesField"
      ]
    }
  ],
  "data": {
    "myModel": {
      "id": "1",
      "myChoicesField": null
    }
  }
}

I imagine the issue is related to the work in graphql-core to related to enum fields

Improved GraphQLEnumType serialization allowing python Enum values 0cef6fb 24687b6

[atomboulian]

I am experiencing the same thing - only started noticing it Monday morning when we got in - Friday it was working perfectly. Thank you for opening this @picturedots.

[picturedots]

It seems like the real issue is with graphql-core 2.1 -- I've tried to track down the issue a bit and added an issue there.

[atomboulian]

Thank you @picturedots. I'll chime in.

[sciyoshi]

I wasn't able to reproduce this, here's a test case:

import graphene
from graphene_django import DjangoObjectType
from django.db import models

class Car(models.Model):
    class Meta:
        app_label = 'app'

    choice = models.IntegerField(choices=[(1, 'Blue'), (2, 'Green')], null=True)

class CarNode(DjangoObjectType, model=Car):
    pass

class Query(graphene.ObjectType):
    car = graphene.Field(CarNode)

    def resolve_car(self, info):
        return Car(choice=None)
    
schema = graphene.Schema(query=Query)
result = schema.execute('{ car { choice } }')

print(result.data, result.errors)

[atomboulian]

@sciyoshi This is happening for CharField's, not IntegerField's (as far as I can tell, since I don't have IntegerField's in my application). The major difference I am noticing is that for CharFields, they must be blank=True instead of null=True.

@picturedots is your myChoicesField a CharField or some other field?

[picturedots]

@atomboulian Yes I can confirm that it's a CharField, For example, I have a field defined like

PERIODIC_INTERVAL_CHOICES = (('Weekly', 'Weekly'),
     ('Bi-Weekly', 'Bi-Weekly'),
      ('Monthly', 'Monthly'),
      ('Quarterly', 'Quarterly'),
      ('Semi-Annually', 'Semi-Annually'),
      'Annually', 'Annually'))

payment_frequency = models.CharField(
    blank=True,
    null=True,
    choices=PERIODIC_INTERVAL_CHOICES,
    max_length=13)

I get the error whenever fetching "payment_frequency" and there is a blank or null value for that object.

I also get the error if null=True is removed, which is actually the correct way to represent an empty value in this case.

[atomboulian]

Yep, exactly.

[ikedumancas]

@sciyoshi I'm having this issue as well.

The code below will give me an error saying Cannot return null for non-nullable field ModelObjectType.frequency.

FREQUENCIES = (
    ('TWO_WEEKS', 'Every Two Week'),
    ('FOUR_WEEKS', 'Every Four Weeks')
)

frequency = models.CharField(choices=FREQUENCIES, blank=True)

If I add a null=True to the choice field, it will return a null value instead of an empty string.

If I add an empty string to the choices like this:

FREQUENCIES = (
    ('', '----'),
    ('TWO_WEEKS', 'Every Two Week'),
    ('FOUR_WEEKS', 'Every Four Weeks')
)

frequency will return A_

[atomboulian]

@ikedumancas Yep not good to put null=True on CharFields in Django - https://docs.djangoproject.com/en/2.1/ref/models/fields/#null

We should be able to use blank=True though, and it's not working.

I was curious about trying the empty string case as you did. You're literally getting "A_" in your responses that have an empty string though? Can you post your response? That is so weird!

Thanks for posting!

[ikedumancas]

@atomboulian Yeah. It's weird. It has to do with this code in converter.py

[picturedots]

I've experienced the issue with blank=True as well. In order to not confuse issues I've created a separate (but related) issue. #503 .

[eamigo86]

Hi @picturedots, I have tried your solution but still the error reported.

[picturedots]

The same error as reported is also an issue with graphene-django 2.2.0