当有人使用 Firebase 关注其他人时，如何触发云功能？我正在使用 Atom 和 Xcode

Question

我正在使用 Firebase，我想在“A 人”关注“B 人”时触发通知。

这是我的代码：

exports.observeFollowing = functions.database.ref('/added/{followerID}/{followingID}').onCreate((snapshot, context) => {
var followerID = context.params.followerID;
var followingID = context.params.followingID;

console.log('User: ' + followerID + ' is following: ' + followingID);

//trying to figure out fcmtoken to send a notification
return admin.database().ref('/users/' + followingID).once('value', snapshot => {

var userWeAreFollowing = snapshot.val();

return admin.database().ref('/users/' + followerID).once('value', snapshot => {

  var userDoingTheFollowing = snapshot.val();

  var payload = {
    notification: {
      title: "Someone added you as a friend",
      body: userDoingTheFollowing.username + ' is now following you'
    }
  }

  return admin.messaging().sendToDevice(userWeAreFollowing.fcmToken, payload)
    .then(response => {
      console.log("Successfully sent message:", response);
      return response
    }).catch(function(error) {
      console.log("Error sending message:", error);
    });
   })
  })
 });

控制台打印

('User: ' + followerID + ' is following: ' + followingID)

部分，但不显示通知。我之前测试过云通知，它们有效，但由于某种原因不起作用。在日志中，它说：

成功发送消息：{ 结果：[ { 错误： [FirebaseMessagingError] } ]," "failureCount: 1," "successCount: 0,"

所以我知道直到

console.log('User: ' + followerID + ' is following: ' + followingID);

为止一切都有效。但我不确定通知功能是否被调用。我是否缺少分号或其他内容？我实在想不通。另外，

failureCount

是什么意思？是说通知功能吗？

Answer 1

如 Cloud Functions doc 中所述，您需要使用 Promise 来管理异步 Firebase 操作。您正在使用

once()

方法的回调版本：您需要使用 Promise 版本，如下所示：

exports.observeFollowing = functions.database.ref('/added/{followerID}/{followingID}').onCreate((snapshot, context) => {

    const followerID = context.params.followerID;
    const followingID = context.params.followingID;

    let userWeAreFollowing;

    console.log('User: ' + followerID + ' is following: ' + followingID);


    return admin.database().ref('/users/' + followingID).once('value')
        .then(snapshot => {

            userWeAreFollowing = snapshot.val();

            return admin.database().ref('/users/' + followerID).once('value')

        })
        .then(snapshot => {

            const userDoingTheFollowing = snapshot.val();

            const payload = {
                notification: {
                    title: "Someone added you as a friend",
                    body: userDoingTheFollowing.username + ' is now following you'
                }
            }

            return admin.messaging().sendToDevice(userWeAreFollowing.fcmToken, payload)

        }).catch(function (error) {
            console.log("Error sending message:", error);
            return null;
        });

});

---

如果您想在成功后在控制台中记录一条消息，请执行以下操作：

    // ...
    .then(snapshot => {

        const userDoingTheFollowing = snapshot.val();

        const payload = {
            notification: {
                title: "Someone added you as a friend",
                body: userDoingTheFollowing.username + ' is now following you'
            }
        }

        return admin.messaging().sendToDevice(userWeAreFollowing.fcmToken, payload)
    })
    .then(response => {
         console.log("Successfully sent message:", response);
         return null;
    }).catch(function (error) {
         console.log("Error sending message:", error);
         return null;
    });