使用Express GraphQL和React-GraphQL订阅Apollo

Question

我按照Apollo的文档在客户端和服务器上设置GraphQL订阅，虽然我已经完成了90%，但我不知道如何设置订阅通道以及如何将突变连接到这些通道，以便每当突变发生时，服务器都会将新html" target="_blank">数据推送到客户端。（对于内容，我正在制作一个Reddit克隆，人们可以在其中发布主题，其他人可以对其发表评论。所以当你看到“Topics”或“TopicList”时，把它们想象成帖子。）

到目前为止，我已经成功地为订阅设置了Apollo客户端：

const wsClient = new SubscriptionClient('ws://localhost:3001/subscriptions', {
  reconnect: true
});

const networkInterface = createNetworkInterface({
    uri: '/graphql',
    opts: {
        credentials: 'same-origin'
    }
});

const networkInterfaceWithSubscriptions = addGraphQLSubscriptions(
  networkInterface,
  wsClient,
);

const client = new ApolloClient({
    networkInterface: networkInterfaceWithSubscriptions,
    dataIdFromObject: o => o.id
});

我还为订阅设置了后端。这是我的服务器。js文件：

//===========================================================
//Subscription Managaer
//===========================================================
const pubsub = new PubSub();
const subscriptionManager = new SubscriptionManager({
  schema: schema,
  pubsub: pubsub
});

//=====================================
//WebSocket + Express Server
//=====================================

const server = createServer(app);

//setup listening port
server.listen(3001, ()=>{
    new SubscriptionServer(
    {
        subscriptionManager: subscriptionManager,
        onConnect: (connectionParams, webSocket) => {
            console.log('Websocket connection established');
        },
        onSubscribe: (message, params, webSocket) => {
            console.log("The client has been subscribed", message, params);
        },
        onUnsubsribe: (webSocket) => {
            console.log("Now unsubscribed");
        },
        onDisconnect: (webSocket) => {
            console.log('Now disconnected');
        }
    }, 
    {
        server: server,
        path: '/subscriptions',
    });
    console.log('Server is hot my man!');
})

我知道这些都是成功的，因为我在终端中记录了“Websocket连接已建立”消息。

接下来是实际订阅-我创建了一个订阅模式类型（就像查询和突变）：

const SubscriptionType = new GraphQLObjectType({
    name: 'Subscription',
    fields: () => ({
        topicAdded: {
            type: TopicType,
            args: {repoFullName: {type: GraphQLString}}, //I don't understand what repoFullName is - I was trying to follow the Apollo docs, but they never specified that
            resolve(parentValue, args){
                return parentValue;
            }

        }
    })
});

module.exports = SubscriptionType;

并将其合并到我的根模式中。因此，当我签出GraphiQL时，我看到：这个订阅在Docs侧菜单中可用，我的GraphiQIL UI成功地显示了订阅模式

在我的React组件中，我使用Apollo的subscribeToMore方法成功地“订阅”了它：

const TOPICS_SUBSCRIPTION = gql`
    subscription OnTopicAdded($repoFullName: String){
        topicAdded(repoFullName: $repoFullName){
            id
        }
    }
`;

class TopicList extends Component {
    componentDidMount() {
        this.createMessageSubscription = this.props.data.subscribeToMore({
          document: TOPICS_SUBSCRIPTION,
          // updateQuery: (previousState, {subscriptionData}) => {
          //   const newTopic = subscriptionData.data.Topic.node
          //   const topics = previousState.findTopics.concat([newTopic])
          //   return {
          //     findTopics: topics
          //   }
          // },
          onError: (err) => console.error(err)
        })

      } //...

我会在终端上收到“客户端已订阅”的消息。但这就是我被困的地方。我已经阅读了SubscriptionManager的SetupFunction，但它没有包含在Apollo的文档中。而且我找不到如何将“createTopic”变体映射到这个订阅，以便每当有人添加新主题时，它都会在TopicList中弹出。

我意识到这真的很长，但我一直在想下一步该怎么做。任何帮助都将不胜感激！！感谢您的阅读！

Answer 1

是的，您缺少设置功能。您可以查看此链接GraphQL订阅文档或此示例。

工作原理：首先，您需要发布更改数据的通道。在您的情况下，它可能如下所示：

const manager = new sub.SubscriptionManager({
  schema,
  pubSub,

  setupFunctions: {
    topicAdded: (options, args) => ({ // name of your graphQL subscription
      topicAddedChannel: { // name of your pubsub publish-tag
        filter: (topic) => {
          console.log(topic); //should always show you the new topic if there is a subscribed client
          return true; // You might want to add a filter. Maybe for guest users or so
        },
      },
    }),
  },
});