javascript - Apollo "Subscription field must return Async Iterable. Received: undefined"

Question

我有一个触发 channel 事件“countIncr”的突变，但我没有看到事件的相应订阅与事件负载一起触发。

更新:我已经对这篇文章进行了多次更新，现在我正在更改标题以更能代表我所在的位置。

我收到 graphqlPlayground 错误

"Subscription field must return Async Iterable. Received: undefined"

我遇到问题的 TGRstack 复制: https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/

没有 TGRstack 的工作再现: https://github.com/Falieson/fullstack-apollo-subscription-example

前端: https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/blob/master/counter-ui/src/app/routes/Home/HomePage.tsx

const COUNTER_SUBSCRIPTION = gql`
subscription onCountIncr {
  count
}
`

const Counter = () => (
  <Subscription
    subscription={COUNTER_SUBSCRIPTION}
  >
    {({ data, loading }) => {
      console.log({loading, data})
      return loading
        ? <h1>Loading ...</h1>
        : data.count
          ? <h2>Counter: {data.count}</h2>
          : <h1>Counter Subscription Not Available</h1>
    }}
  </Subscription>
)

BE 解析器:https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/blob/master/counter-service/src/gql/Resolvers.ts

BE 架构:https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/blob/master/counter-service/src/gql/Schema.ts

BE Controller :https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/blob/master/counter-service/src/gql/Counter.ts

const count = {
  resolve: data => {
    console.log('CounterSub>', {data})
    return data
  },
  subscribe: () => pubsub.asyncIterator(['countIncr'])
}

const CounterSubscriptions = {
  count
}

async function countIncr(root: any, args: any, context: any) {
  const count = Counter.increment()
  await pubsub.publish('countIncr', count )
  console.log('countIncr', '>>>', { count })
  return count
}

这是运行完 Readme.md 中的#getting started 说明后的服务日志

[FE] GET /favicon.ico 200 2.465 ms - 1551                   # WEBCLIENT LOADED
[BE] CounterSub> { data: undefined }                        # SUBSCRIPTION REQUEST
[BE] { data: [Object: null prototype] { count: null } }     # SUBSCRIPTION RESULT
[BE] POST / 200 21.254 ms - 24
[BE] 2019-05-10 11:37:20 [info]:     HELLO                  # APOLLO CLIENT CONNECTED AGAIN (why always 2?)
[BE] countIncr >>> { count: 1 }                             # MUTATION REQUEST
[BE] { data: [Object: null prototype] { countIncr: 1 } }    # MUTATION RESPONSE
[BE] POST / 200 13.159 ms - 25
[BE] countIncr >>> { count: 2 }                             # MUTATION REQUEST
[BE] { data: [Object: null prototype] { countIncr: 2 } }    # MUTATION RESPONSE
[BE] POST / 200 4.380 ms - 25

更新

如果您尝试克隆存储库，但在运行 nps 后它无法正常工作，因为 nps setup 中缺少一个步骤。我已通过改进的 nps 设置 将更新推送到堆栈。

更新 2

根据最新提交更新相关代码和链接

更新 3

有些人建议 pubsub 应该是单一导入。我已经更新了代码，但这会产生一个新错误:

Error: Apollo Server requires either an existing schema, modules or typeDefs

更新 4

许多试图寻找导入/导出错误(？)的小改动现在都出现了错误。我通过强化导入修复了此错误(索引文件未正确导出存在一些问题)。

"message": "Subscription field must return Async Iterable. Received: undefined"

没有 TGRstack 的工作复制:https://github.com/Falieson/fullstack-apollo-subscription-example

更新 5

我解模块化/分解了一堆东西，以便更容易跟踪发生了什么，但仍然遇到相同的错误

Answer 1

我在两个地方解决了这个问题

1. ApolloServer.installSubscriptionHandler() 暂时 替换 middleware.apolloSubscriptions() 。我按照本指南配置订阅中间件:https://www.apollographql.com/docs/graphql-subscriptions/express所以我猜测其中一个软件包或指南本身的版本有问题。

    ApolloServer.installSubscriptionHandlers(ws)

    const listener = ws.listen({port: config.PORT}, () => {
      middleware.apolloSubscriptions(ws)
      // middleware.apolloSubscriptions(ws)

1. terminatingLink 和 getMainDefinition 是客户端所必需的 https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/commit/75b6165f2dc1d035a41f1129f7386a1e18c7ba53#diff-2c47ef33b8ed0e4c893cbc161bcf7814R37

  private _terminatingLink = split(
    ({ query }) => {
      const { kind, operation } = getMainDefinition(query)
      return (
        kind === 'OperationDefinition' && operation === 'subscription'
      )
    },
    this._wsLink,
    this._httpLink,
  )