Delete mutation in Django GraphQL - django

Question

The docs of Graphene-Django pretty much explains how to create and update an object. But how to delete it? I can imagine the query to look like
mutation mut{
deleteUser(id: 1){
user{
username
email
}
error
}
}
but i doubt that the correct approach is to write the backend code from scratch.

Answer 1

Something like this, where UsersMutations is part of your schema:
class DeleteUser(graphene.Mutation):
ok = graphene.Boolean()
class Arguments:
id = graphene.ID()
#classmethod
def mutate(cls, root, info, **kwargs):
obj = User.objects.get(pk=kwargs["id"])
obj.delete()
return cls(ok=True)
class UserMutations(object):
delete_user = DeleteUser.Field()

Answer 2

Here is a small model mutation you can add to your project based on the relay ClientIDMutation and graphene-django's SerializerMutation. I feel like this or something like this should be part of graphene-django.
import graphene
from graphene import relay
from graphql_relay.node.node import from_global_id
from graphene_django.rest_framework.mutation import SerializerMutationOptions
class RelayClientIdDeleteMutation(relay.ClientIDMutation):
id = graphene.ID()
message = graphene.String()
class Meta:
abstract = True
#classmethod
def __init_subclass_with_meta__(
cls,
model_class=None,
**options
):
_meta = SerializerMutationOptions(cls)
_meta.model_class = model_class
super(RelayClientIdDeleteMutation, cls).__init_subclass_with_meta__(
_meta=_meta, **options
)
#classmethod
def get_queryset(cls, queryset, info):
return queryset
#classmethod
def mutate_and_get_payload(cls, root, info, client_mutation_id):
id = int(from_global_id(client_mutation_id)[1])
cls.get_queryset(cls._meta.model_class.objects.all(),
info).get(id=id).delete()
return cls(id=client_mutation_id, message='deleted')
Use
class DeleteSomethingMutation(RelayClientIdDeleteMutation):
class Meta:
model_class = SomethingModel
You can also override get_queryset.

Answer 3

I made this library for simple model mutations: https://github.com/topletal/django-model-mutations , you can see how to delete user(s) in examples there
class UserDeleteMutation(mutations.DeleteModelMutation):
class Meta:
model = User

Answer 4

Going by the Python + Graphene hackernews tutorial, I derived the following implementation for deleting a Link object:
class DeleteLink(graphene.Mutation):
# Return Values
id = graphene.Int()
url = graphene.String()
description = graphene.String()
class Arguments:
id = graphene.Int()
def mutate(self, info, id):
link = Link.objects.get(id=id)
print("DEBUG: ${link.id}:${link.description}:${link.url}")
link.delete()
return DeleteLink(
id=id, # Strangely using link.id here does yield the correct id
url=link.url,
description=link.description,
)
class Mutation(graphene.ObjectType):
create_link = CreateLink.Field()
delete_link = DeleteLink.Field()