Graphene always returning "none" in Json

Question

Im fairly new to GraphQL and Graphene so it's hard for me to grasp whats wrong with my code. I can't even succeed with the simplest of the examples with GraphQL. Here is my code:

models.py

class Task(models.Model):
task_name = models.CharField('Aufgabe', max_length=255)
project = models.ForeignKey(Project, on_delete=models.CASCADE)
done = models.BooleanField(verbose_name="Erledigt", default=False)

def __str__(self):
    return self.task_name

schema.py

class Task(models.Model):
task_name = models.CharField('Aufgabe', max_length=255)
project = models.ForeignKey(Project, on_delete=models.CASCADE)
done = models.BooleanField(verbose_name="Erledigt", default=False)

def __str__(self):
    return self.task_name

My Query in the same file:

class TaskQuery(graphene.ObjectType):

all_tasks = graphene.List(TaskType)

def resolve_all_tasks(self, info, **kwargs):
    return Task.objects.all()

Another Queryfunction:

class Query(graphene.ObjectType):
tasks = TaskQuery.all_tasks

projects = ProjectQuery.all_projects

This is my schema.py int the settings directory:

import graphene

from todo import schema 

class Query(schema.Query):
    pass

class Mutation(schema.Mutation):
    pass

schema = graphene.Schema(query=Query, mutation=Mutation)

When opening GraphiQL I can see the Query in the docs, but when I try to use this query like so (for example):

query {
  tasks{
    id
    taskName
    done
  }
}

it always returns this:

{
  "data": {
    "tasks": null
  }
}

Although I am pretty sure that I have entries in my Database that should be displayed there. I have checked the beginners Tutorial a view times and I can't even pass the first hurdle. Is there something I am missing?

frozenOne · Accepted Answer · 2020-04-10T20:09:18.450

1

So graphene relies heavily on types. I suggest making the following changes:

from graphene.relay import Node
from graphene import ObjectType, JSONField, String
from graphene_django import DjangoObjectType

from app.models import Task, Project

class TaskType(DjangoObjectType): # this is basically your nodes in the graph
    class Meta:
        filter_fields = {'id': ['exact']}
        model = Task
        interfaces = (Node,)

class ProjectType(DjangoObjectType): # FK should have a type as well
    class Meta:
        filter_fields = {'id': ['exact']}
        model = Project
        interfaces = (Node,)


class TasksQuery(ObjectType):
    task = Node.Field(TaskType)
    all_tasks = DjangoFilterConnectionField(TaskType)

In your schema.py make the following changes:

import graphene

from todo import schema

class Query(schema.TasksQuery):
    pass

class Mutation(schema.Mutation):
    pass

schema = graphene.Schema(query=Query, mutation=Mutation)

And then query using:

query {
  allTasks {
    id
    taskName
    done
  }
}

Lemme know if this works.

edited Apr 10 '20 at 20:09

answered Apr 09 '20 at 09:13

frozenOne

558
2
8

Dude thanks! I have already lost hope, that someone will help. I will test it asap. – Helmut K. Apr 10 '20 at 19:35
1

Lemme know I'm online. @Helmut – frozenOne Apr 10 '20 at 19:45
Thanks a lot. So I did everything as you told me, now it throws an error which is a huge stack trace. The last line says ```AssertionError: The type TaskType doesn't have a connection``` Should I post the whole stack trace or is this already helpful? – Helmut K. Apr 10 '20 at 19:57
1

@HelmutK. See the edit, I forgot to add the `interfaces` thing. Sorry. – frozenOne Apr 10 '20 at 20:10
Yes it works! Thanks @frozenOne. I had to tweak the query a little bit like so ```query { allTasks { edges { node { id taskName done } } } }``` but never the less, I can query my tasks from my database. Thanks a lot. Its so frustrating when you get stuck so early on in your learning process. You helped a lot. :D – Helmut K. Apr 10 '20 at 20:24
1

Next time you get stuck, try reddit as well, it's more accessible than stack overflow. They have dedicated community for graphql. And someone is bound to see your question. – frozenOne Apr 10 '20 at 20:35

Graphene always returning "none" in Json

1 Answers1