每个 then() 都应该在 firebase 云函数中返回一个值或抛出错误

Question

我正在使用 javascript 为 firebase 编写云函数，而我部署函数时发生错误并终止部署过程。

错误：每个 then() 都应该返回一个值或抛出

如何解决此错误？

下面我附上了我的代码。

exports.sendNotificationForLikeOrFollow = functions.database.ref('/USER_MANAGEMENT/USER_ACTIVITY/{activityId}').onCreate((snap, context) => {

  var type = snap.val().ACTIVITY_TYPE;

  if (type=='Comment') {
    return; //There is a separate function for comment notification
  }

  if (type=='Like') {

    const likeUserId = snap.val().BY_USER_NODE_NAME;
    const publishedUserId = snap.val().PUBLISHED_USER_NODE_NAME;
    const puplishedContentId = snap.val().LIKE_PUBLISHED_CONTENT_NODE_NAME;
    const likedUserName = snap.val().BY_USER_NAME;
    const likedUserPhotoUrl = snap.val().BY_USER_PHOTO_URL;

    // var publishedUserRef = event.data.ref.parent.parent.child('USERS/'+publishedUserId);
    // var likedUserRef = event.data.ref.parent.parent.child('USERS/'+likeUserId);
    var publishedUserRef = db.ref("USER_MANAGEMENT/USERS/"+publishedUserId);
    var likedUserRef = db.ref("USER_MANAGEMENT/USERS/"+likeUserId);

    return Promise.all([publishedUserRef.once('value')]).then(function(snaps) {

        var data = snaps[0].val();
        const fcmToken = data.FCM_TOKEN;

          // Notification details.
          const payload = {
            notification: {
              title: '❤️ You got a new like!',
              body: likedUserName+` liked your artwork.`,
              sound: 'default',
              icon: '',
              byUserId: likeUserId,
              byUserName: likedUserName,
              type: 'Like',
              likedPuplishedContentId: puplishedContentId,
              publishedUserId: publishedUserId,
              byUserPhotoUrl: likedUserPhotoUrl,
              badge : '1'
            }
          };

          // Listing all tokens.
          const tokens = fcmToken;

          // Send notifications to all tokens.
          return admin.messaging().sendToDevice(tokens, payload).then(response => {
            // For each message check if there was an error.
            response.results.forEach((result, index) => {
              console.log('FcmToken: ', tokens);
              const error = result.error;
              if (error) {
                console.log('Error Occured:', error);
              }
            });
            console.log('User Liked');
          });
    });
  }

  if (type=='Follow') {
    const followerUserId = snap.val().BY_USER_NODE_NAME;
    const followeeUserId = snap.val().FOLLOWING_USER_NODE_NAME;
    const followerUserName = snap.val().BY_USER_NAME;
    const followerPhotoUrl = snap.val().BY_USER_PHOTO_URL;

    // var followerUserRef = event.data.ref.parent.parent.child('USERS/'+followerUserId);
    // var followeeUserRef = event.data.ref.parent.parent.child('USERS/'+followeeUserId);
    var followerUserRef = db.ref('USER_MANAGEMENT/USERS/'+followerUserId);
    var followeeUserRef = db.ref('USER_MANAGEMENT/USERS/'+followeeUserId);
    var isFollow;

    //const followeeFollowingRef = event.data.ref.parent.parent.child('FOLLOWING/'+followeeUserId+'/'+followerUserId);
    const followeeFollowingRef = db.ref('USER_MANAGEMENT/FOLLOWING/'+followeeUserId+'/'+followerUserId);

    return Promise.all([followeeUserRef.once('value')]).then(function(snaps) {

        var data = snaps[0].val(); // Get whole USER_MANAGEMENT snapshot

        const fcmToken = data.FCM_TOKEN

        followeeFollowingRef.once('value').then(function(followeeSnapshot) {

          if (followeeSnapshot.exists()) {
            isFollow = 'YES';
            console.log('FOLLOW YES');
          }else{
            isFollow = 'NO';
            console.log('FOLLOW NO');
          }

            // Notification details.
            const payload = {
              notification: {
                title: '???? You have a new follower!',
                body: followerUserName+` is now following you.`,
                sound: 'default',
                icon: '',
                byUserId: followerUserId,
                byUserName: followerUserName,
                type: 'Follow',
                isFollow: isFollow,
                byUserPhotoUrl: followerPhotoUrl,
                badge : '1'
              }
            };

            // Listing all tokens.
            const tokens = fcmToken;
            console.log('FcmToken: ', tokens);
            // Send notifications to all tokens.
            return admin.messaging().sendToDevice(tokens, payload).then(response => {
              // For each message check if there was an error.
              response.results.forEach((result, index) => {
                const error = result.error;
                if (error) {

                  console.log('Error Occured:', error);
                }
              });
              console.log('User Followed');
            });
      });    
    });
  }
});

该功能在几年前就已经部署并且运行良好。但现在我尝试将相同的代码部署到另一个项目，但由于上述错误而停止。

Answer 1

您没有正确chain Firebase 异步方法返回的不同承诺。

另外，请注意您不需要使用Promise.all()，因为once() 方法只返回一个Promise。同样，您应该正确链接 Promises，而不是使用Promise.all()，它应该用于并行而不是按顺序执行异步方法。

因此，以下应该可以解决问题（未经测试）：

exports.sendNotificationForLikeOrFollow = functions.database.ref('/USER_MANAGEMENT/USER_ACTIVITY/{activityId}').onCreate((snap, context) => {

    var type = snap.val().ACTIVITY_TYPE;

    if (type == 'Comment') {
        return null; //There is a separate function for comment notification
    }

    if (type == 'Like') {

        const likeUserId = snap.val().BY_USER_NODE_NAME;
        const publishedUserId = snap.val().PUBLISHED_USER_NODE_NAME;
        const puplishedContentId = snap.val().LIKE_PUBLISHED_CONTENT_NODE_NAME;
        const likedUserName = snap.val().BY_USER_NAME;
        const likedUserPhotoUrl = snap.val().BY_USER_PHOTO_URL;

        var publishedUserRef = db.ref("USER_MANAGEMENT/USERS/" + publishedUserId);

        return publishedUserRef.once('value')
            .then(snaps => {

                var data = snaps[0].val();
                const fcmToken = data.FCM_TOKEN;

                // Notification details.
                const payload = {
                    notification: {
                        title: '❤️ You got a new like!',
                        body: likedUserName + ` liked your artwork.`,
                        sound: 'default',
                        icon: '',
                        byUserId: likeUserId,
                        byUserName: likedUserName,
                        type: 'Like',
                        likedPuplishedContentId: puplishedContentId,
                        publishedUserId: publishedUserId,
                        byUserPhotoUrl: likedUserPhotoUrl,
                        badge: '1'
                    }
                };

                // Listing all tokens.
                const tokens = fcmToken;

                // Send notifications to all tokens.
                return admin.messaging().sendToDevice(tokens, payload);
            })
            .then(response => {
                // For each message check if there was an error.
                response.results.forEach((result, index) => {
                    console.log('FcmToken: ', tokens);
                    const error = result.error;
                    if (error) {
                        console.log('Error Occured:', error);
                    }
                });
                console.log('User Liked');
                return null;
            });
    }

    if (type == 'Follow') {
        // See above, it is similar
    }
});