Mutations - batch creation of objects

Question

I want to use graphene to create many people in one go. The document only mention the way to create one person like this:

class CreatePerson(graphene.Mutation):
class Input:
    name = graphene.String()
    age = graphene.Int()

ok = graphene.Boolean()
person = graphene.Field(lambda: Person)

@staticmethod
def mutate(root, args, context, info):
    person = Person(name=args.get('name'), age=args.get('age'), mobile=args.get('mobile'))
    ok = True
    return CreatePerson(person=person, ok=ok)

are there any ways to get it done?

Captious

FYI you can post your solution as an answer and accept it so people coming after you can easily see the final solution. – Chose

Answer 1

I can figure out a solution base on the answer of Jan Hančič

There is a type called graphene.InputObjectType to use in this case

The solution can be

class PersonInput(InputObjectType):
    name = graphene.String()
    age = graphene.Int()

class CreatePeople(graphene.Mutation):
    class Input:
       people = graphene.List(PersonInput)

    people = graphene.List(lambda: Person)

    @staticmethod
    def mutate(root, args, context, info):
        people = [Person.objects.create(name=person.name, age=person.age) for person in args.get('people')]
        return CreatePeople(people=people)

Captious

I created a mutation this way but I can't find a way how to write a graphql query for this. How do you do that? – Porscheporsena

@KarinaKlinkevičiūtė you can find the answer here - docs.graphene-python.org/projects/django/en/latest/queries – Captious

Answer 2

Instead of using a mutation that creates a list of objects, you can also call a mutation that creates one objects multiple times in one GraphQL request. This is accomplished using GraphQL Aliases:

mutation {
  c001: createPerson(
    name: "Donald Duck"
    age: 42
  ) {
    id
  }

  c002: createPerson(
    name: "Daisy Duck"
    age: 43
  ) {
    id
  }

  c003: createPerson(
    name: "Mickey Mouse"
    age: 44
  ) {
    id
  }
}

Zilvia

the link to the FAQ is dead. – Immunotherapy

which one is better, the batch of list or batch of alias? – Separatist

Answer 3

Make your mutation input a list and return a list of created people. Something like this:

class CreatePerson(graphene.Mutation):
    class Input:
        name = graphene.List(graphene.String)

    ok = graphene.Boolean()
    people = graphene.List(Person)

    @staticmethod
    def mutate(root, args, context, info):
        people = [Person(name=name) for name in args.get('name)]
        ok = True
        return CreatePerson(people=people, ok=ok)

Predesignate

great! but how can I deal with more than one field. E.g. name, address and age for the person? – Captious

You can have complex input types, see the docs: docs.graphene-python.org/en/latest/types/mutations – Chose

Hi Jan, I use the InputObject and it worked but the data was not saved to the db. Would you mind helping on this. Thank you very much! – Captious

Answer 4

Receive a list of input, create all instances and return them all

The model node/type should be like-

class UserType(DjangoObjectType):

    class Meta:
        model = User
        interfaces = (CustomGrapheneNode, )
        filter_fields = {}
        only_fields = (
            'name',
            'email'
        )

Define Input fields

class UserInput(graphene.InputObjectType):
    name = graphene.String(required=True)
    password = graphene.String(required=True)

Mutation class

class CreateUser(graphene.Mutation):
    users = graphene.List(UserType)

    class Input:
        data = graphene.List(UserInput)

    Output = graphene.List(UserType)

    def mutate(self, info, data):
        users = []
        for item in data:
            user = User.objects.create(name=data['name'], 
                                       password=data['password'])
            users.append(user)
        return users

make this mutation callable by main schema

class Mutation():
    create_user = CreateUser.Field()

the Mutation Query view will be as -

mutation{
    createUser(data:[{name:"john", password:"1234"},
                     {name:"john", password:"1234"}]) {
        user{
            name
        }
    }    
}

Cung

good solution. Just to add you could use the bulk_create() method there in the mutate() function as described in the docs: docs.djangoproject.com/en/3.2/ref/models/querysets – Might

in case someone else tries this answer and you run into error, in the mutate function just change for item in data: user = User.objects.create(name=data['name'], password=data['password']) to instead: for item in data: user = User.objects.create(name=item['name'], password=item['password']) – Might