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

Question

我有一个触发频道事件的突变 'countIncr'，但我没有看到活动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"

TGRstack 复制我遇到了问题： https://github.com/TGRstack/tgr-apollo-subscription-example-microservice/

没有 TGRstack 的工作复制： 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 控制器：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
}

这是您运行通过 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ning nps 之后它无法正常工作，因为 nps setup 中缺少一个步骤。我已将更新推送到堆栈，改进了 nps setup。

更新 2

根据最新提交更新了相关代码和链接

更新 3

有人建议 pubsub 应该是单个导入。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

试图追捕 import/export 错误（？）的许多小改动现在出现错误。我通过强化导入修复了此错误（索引文件未正确导出时存在一些问题）。

"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 demodularized/decomposed 一堆东西可以更容易地跟踪发生了什么但仍然得到相同的错误

Answer 1

我在两个地方解决了这个问题

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 所以我猜这些包之一的版本或指南本身有问题。


    ApolloServer.installSubscriptionHandlers(ws)

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

客户端需要 terminatingLink 和 getMainDefinition 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,
  )

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

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

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