带graphql的Aiohttp:字符串不能表示值

Question

我正在用graphql（aiohttp_graphql）创建一个aiohttp api，并给出了这个问题。为什么?

aiohttp版本：aiohttp==3.7.3 -吉特+https://github.com/graphql-python/aiohttp-graphql.git@5F75803010761DD7DE33B44BC92F30B2695F2D523#egg=aiohttp#U图形

这是我的代码：

import asyncio
from aiohttp import web
from aiohttp_graphql import GraphQLView
from graphql.execution.executors.asyncio import AsyncioExecutor
from graphql import (graphql, GraphQLSchema, GraphQLObjectType, GraphQLField, GraphQLString)

async def resolve_hello(root, info):
    await asyncio.sleep(3)
    return 'World!'

Schema = GraphQLSchema(
    query=GraphQLObjectType(
        name='HelloQuery',
        fields={
            'hello': GraphQLField(
                GraphQLString,
                resolve=resolve_hello),
        },
    ))

app = web.Application()

GraphQLView.attach(
    app,
    route_path='/graphql',
    schema=Schema,
    graphiql=True,
    executor=AsyncioExecutor())

if __name__ == '__main__':
    web.run_app(app)

运行GraphiQL时：

query {
  hello
}

图形结果：

{
  "errors": [
    {
      "message": "String cannot represent value: <coroutine resolve_hello>",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "hello"
      ]
    }
  ],
  "data": {
    "hello": null
  }
}

终端返回：运行时警告：从未等待协同路由“resolve\u hello”