我对Apollo GraphQL的订阅有问题。尝试启动订阅时，我得到以下回报：
"Subscription field must return Async Iterable. Received: { pubsub: { ee: [EventEmitter],subscriptions: {},subIdCounter: 0 },pullQueue: [],pushQueue: [],running: true,allSubscribed: null,eventsArray: [\"H-f_mUvS\"],return: [function return] }"
我还有其他订阅设置，并且功能完全正常-因此，我可以确认网络服务器设置正确。
我很好奇，是否有人曾经遇到过这个问题。
PR diff中的源代码（这是一个开源项目）： https://github.com/astronomer/houston-api/pull/165/files
我认为这不是您发布的PR所特有的问题。如果有任何订阅按原样工作，我会感到惊讶。
您的subscribe函数应返回AsyncIterable，作为错误状态。由于它返回对createPoller的调用，因此createPoller应该返回一个AsyncIterable。但是，该函数的外观如下：
export default function createPoller(
func,pubsub,interval = 5000,// Poll every 5 seconds
timeout = 3600000 // Kill after 1 hour
) {
// Gernate a random internal topic.
const topic = shortid.generate();
// Create an async iterator. This is what a subscription resolver expects to be returned.
const iterator = pubsub.asyncIterator(topic);
// Wrap the publish function on the pubsub object,pre-populating the topic.
const publish = bind(curry(pubsub.publish,2)(topic),pubsub);
// Call the function once to get initial dataset.
func(publish);
// Then set up a timer to call the passed function. This is the poller.
const poll = setInterval(partial(func,publish),interval);
// If we are passed a timeout,kill subscription after that interval has passed.
const kill = setTimeout(iterator.return,timeout);
// Create a typical async iterator,but overwrite the return function
// and cancel the timer. The return function gets called by the apollo server
// when a subscription is cancelled.
return {
...iterator,return: () => {
log.info(`Disconnecting subscription ${topic}`);
clearInterval(poll);
clearTimeout(kill);
return iterator.return();
}
};
}
因此createPoller创建了一个AsyncIterable，但是随后创建了它的浅表副本并返回了它。 graphql-subscriptions将iterall的{{1}}用于产生您所看到的错误的检查。由于isAsyncIterable works的方式，浅拷贝不会飞行。您可以自己查看：
isAsyncIterable因此，const { PubSub } = require('graphql-subscriptions')
const { isAsyncIterable } = require('iterall')
const pubSub = new PubSub()
const iterable = pubSub.asyncIterator('test')
const copy = { ...iterable }
console.log(isAsyncIterable(iterable)) // true
console.log(isAsyncIterable(copy)) // false
不应返回浅表副本，而应直接将createPoller方法进行突变：
return