dataloader.py

class SimplyDataloader(DataLoader):
    def batch_load_fn(self, keys):
        """
        batch_load_fn accept list of keys and should return list of promises.
        assert len(keys) == len(promises)
        It calls only one time, with all the keys from the .load(key) calls.
        """
        # heavy calculations will be here. 
        ret = 5
        return Promise.resolve([ret])



class Object(graphene.ObjectType):
    multiply_2 = graphene.Int()
    multiply_3 = graphene.Int()

    @classmethod
    def resolve_multiply_2(cls, root, info, *args, **kwargs):
        def process_data(data):
            return data * 2

        return SimplyDataloader().load('').then(process_data)

    @classmethod
    def resolve_multiply_3(cls, root, info, *args, **kwargs):
        def process_data(data):
            return data * 3

        return SimplyDataloader().load('').then(process_data)

# graphene3 will be supporting more fluent async\await interface:
    @classmethod
    async def resolve_multiply_3(cls, root, info, *args, **kwargs):
        data = await SimplyDataloader().load('')
        returm data * 3