Firebase 云功能无法正确记录

Question

我在每两分钟运行一次的 firebase 函数上运行 pubsub 计划函数。 我尝试记录快照循环收集的事件，但有些事情不正常。

exports.check_event_ended_notification = functions.pubsub.schedule('every 2 minutes').onRun((context) => {
        let default_lineup = "default";
        let events = [];

        return admin.database().ref("Events").once('value')
            .then(snapshot => {
                console.log(("EVENTS number : " + snapshot.numChildren()));
                snapshot.forEach(event_snapshot => {
                    let event_key = event_snapshot.key;
                    let event = event_snapshot.val();
                    events.push(event_key);
                    console.log("EVENT_UID : " + event_key);
                    console.log(("EVENTS : " + events));
                    // iterate through all events and check if they're marked as ended
                    // if not, check if ended
                    let event_status = event[['ended_status']];
                    if (event_status === '0') {
                        // get event date
                        let event_day = event[['date']]['0'];
                        let event_month = event[['date']]['1'];
                        let event_year = event[['date']]['2'];
                        let event_full_date = event_year + "-" + event_month + "-" + event_day;
                        // get today date
                        let today = new Date();
                        let today_day = today.getDate();
                        let today_month = (today.getMonth() + 1);
                        let today_year = today.getFullYear();
                        let today_full_date = today_year + "-" + today_month + "-" + today_day;
                        //create date objects to compare
                        let event_date = new Date(event_full_date);
                        let today_date = new Date(today_full_date);

                        // if event date is in the past
                        // check to see if its marked as ended.
                        if (event_date.getTime() < today_date.getTime()) {
                            console.log("EVENT : past event :  " + event_key);
                            if (event[['ended_status']] === "0") {
                                console.log("EVENT : ended 0  :  " + event_key);
                                //mark as ended
                                // admin.database().ref("Events/"+event_key+"/ended_status").set("1");
                                //create notifications for participation artists
                                for (let artist_key in event[['lineup']]) {
                                    console.log("ARTIST before: " + artist_key);

                                    if (artist_key !== default_lineup) {
                                        console.log("ARTIST after: " + artist_key);

                                        let approved_invitation = event[['lineup']][artist_key]['approved_invitation'];
                                        let handshake_status = event[['lineup']][artist_key]['handshake_status'];
                                        let quit = event[['lineup']][artist_key]['quit'];
                                        let removed = event[['lineup']][artist_key]['removed'];
                                        let event_publish_status = event[['publish_status']];
                                        let owner_uid = event[['owner_uid']];

                                        if (approved_invitation === '1' && handshake_status === '1' && quit === '0' && removed === '0' && event_publish_status === '1') {
                                            return admin.database().ref("Notifications/" + artist_key + "/" + owner_uid + "/" + event['uid']).push({
                                                notification_type: "ended",
                                                seen_status: "0",
                                                timestamp: new Date().getTime()
                                            })
                                        }
                                    }
                                }
                            }
                        }
                    }

                    return null;
                })
            })
    }

虽然开头的 numChildren() 日志显示快照下有 4 个孩子（这是正确的），但 foreach() 方法似乎只运行了两次，收集前两个孩子并将它们添加到“事件”列表。

在此之后日志停止：

2020-07-29T14:22:00.593Z ? check_event_ended_notification: EVENTS number : 4
2020-07-29T14:22:00.593Z ? check_event_ended_notification: EVENT_UID : 3853c2db-f31a-4f46-8c1b-740ca4e3407b
2020-07-29T14:22:00.593Z ? check_event_ended_notification: EVENTS : 3853c2db-f31a-4f46-8c1b-740ca4e3407b
2020-07-29T14:22:00.594Z ? check_event_ended_notification: EVENT_UID : 4253c2db-f31a-4f46-8c1b-740ca4e3407s
2020-07-29T14:22:00.594Z ? check_event_ended_notification: EVENTS : 3853c2db-f31a-4f46-8c1b-740ca4e3407b,4253c2db-f31a-4f46-8c1b-740ca4e3407s

Answer 1

您没有正确管理 Cloud Function 的生命周期。正如doc 中所述，您需要“通过返回 JavaScript 承诺来解析执行异步处理的函数（也称为“后台函数”）。

另外，在一个云函数中，不推荐使用on()方法，它设置了一个监听器，而是once()一个，它“只监听一个指定事件类型的事件，然后停止听。”。

所以以下应该可以解决问题：

exports.check_event_ended_notification = functions.pubsub.schedule('every 2 minutes').onRun((context) => {
    let default_lineup = "default";
    let events = [];

    return admin.database().ref("Events").once('value')  // Note the return here
        .then(snapshot => {

            snapshot.forEach(event_snapshot => {
                let event_key = event_snapshot.key;
                let event = event_snapshot.val();
                events.push(event_key)
                console.log("EVENT_UID : " + event_key);
                console.log(("EVENTS : " + events));
            });
            
            // Do something with events... We don't have enough details
            
            return null;  // Or return a promise

        });

});

---

根据您的评论更新

如果你想在forEach()中写入数据库（这是一个异步过程），你应该使用Promise.all()，以便在所有并行调用异步push()时返回一个promise方法完成。

这里是代码的框架，你应该适应所有的细节：

exports.check_event_ended_notification = functions.pubsub.schedule('every 2 minutes').onRun((context) => {
    let default_lineup = "default";
    let events = [];

    return admin.database().ref("Events/").once('value')
        .then(snapshot => {

            const promises = [];

            snapShot.forEach(event_snapshot => {
                let event_key = event_snapshot.key;
                let event = event_snapshot.val();
                events.push(event_key)
                console.log("EVENT_UID : " + event_key);
                console.log(("EVENTS : " + events));

                promises.push(

                    admin.database().ref("Notifications/" + artist_key + "/" + owner_uid + "/" + event['uid']).push({
                        notification_type: "ended",
                        seen_status: "0",
                        timestamp: new Date().getTime()
                    })

                );

            });
    
            return Promise.all(promises);   // This returns a promise!!

        });

});