Python 3.x 测试GraphQL架构时抛出类型错误

这是我第一次接触石墨烯，我想我的问题很明显

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但当我在最后一步中测试GraphQL模式时，它抛出了一个

TypeError:“对
schema.py试试这个

import graphene
from graphene_sqlalchemy import SQLAlchemyObjectType
from models import (
    Department as DepartmentModel,
    Employee as EmployeeModel,
)


class Department(SQLAlchemyObjectType):
    class Meta:
        model = DepartmentModel


class Employee(SQLAlchemyObjectType):
    class Meta:
        model = EmployeeModel


class Query(graphene.ObjectType):
    all_employees = graphene.List(Employee)
    all_departments = graphene.List(Department)

    def resolve_employees(self, info):
        query = Employee.get_query(info)
        return query.all()

    def resolve_departments(self, info):
        query = Department.get_query(info)
        return query.all()


schema = graphene.Schema(query=Query)