Most APIs don’t just allow you to read data, they also allow you to write.

In GraphQL, this is done using mutations. Just like queries, Relay puts some additional requirements on mutations, but Graphene nicely manages that for you. All you need to do is make your mutation a subclass of relay.ClientIDMutation.

class IntroduceShip(relay.ClientIDMutation):

    class Input:
        ship_name = graphene.String(required=True)
        faction_id = graphene.String(required=True)

    ship = graphene.Field(Ship)
    faction = graphene.Field(Faction)

    def mutate_and_get_payload(cls, input, context, info):
        ship_name = input.get('ship_name')
        faction_id = input.get('faction_id')
        ship = create_ship(ship_name, faction_id)
        faction = get_faction(faction_id)
        return IntroduceShip(ship=ship, faction=faction)

Accepting Files

Mutations can also accept files, that’s how it will work with different integrations:

class UploadFile(graphene.ClientIDMutation):
     class Input:
         # nothing needed for uploading file

     # your return fields
     success = graphene.String()

    def mutate_and_get_payload(cls, input, context, info):
        # When using it in Django, context will be the request
        files = context.FILES
        # Or, if used in Flask, context will be the flask global request
        # files = context.files

        # do something with files

        return UploadFile(success=True)