测试 GraphQL 模式会引发 TypeError

【问题标题】：Testing GraphQL schema throws a TypeError测试 GraphQL 模式会引发 TypeError
【发布时间】：2018-07-05 09:14:37
【问题描述】：

这是我第一次接触石墨烯，我想我的问题很明显......

但是当我在最后一步在这个 step-by-step tutorial 中测试 GraphQL 架构时，它会抛出一个 TypeError: '<' not supported between instances of 'String' and 'NoneType'

我哪里错了？前面的步骤都OK了。

【问题讨论】：

标签： python-3.x graphene-python

【解决方案1】：

试试这个schema.py

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)

【讨论】：