Question

我正在尝试在firebase函数中运行下一个代码，但它给出了无法识别datasnapshot的错误。是什么原因引起的？

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();


exports.updateVotes = functions.database.ref('travels/{travelId}/locations/{locationId}/voting/users')
.onUpdate((userVotes, context) => {
    var travelId = context.params.travelId;
    var locationId = context.params.locationId
    var sumVotes = 0;

    userVotes.forEach((userVote) => {
        sumVotes += userVote.val().userVote;

    })
    // var votes = userVotes.val();
    // for (var vote in votes) {
    //     if (votes.hasOwnProperty(vote)) {
    //         sumVotes += votes[vote].userVote;
    //     }
    // }

    return admin.database()
        .ref('travels/' + travelId + '/locations/' + locationId + '/voting')
        .update({ votes: sumVotes })

})

错误是：

TypeError：userVotes.forEach不是exports.updateVotes.functions.database.ref.onUpdate上的函数

Answer 1

onUpdate不返回DataSnapshot，而是返回Change对象。

您需要选择after或before属性-在写入之前还是写入之后（通常是之后的-这是Firebase中的新数据）需要信息吗？

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();


exports.updateVotes = functions.database.ref('travels/{travelId}/locations/{locationId}/voting/users')
.onUpdate((change, context) => {
    var travelId = context.params.travelId;
    var locationId = context.params.locationId
    var sumVotes = 0;

    var userVotes = change.after;

    userVotes.forEach((userVote) => {
        sumVotes += userVote.val().userVote;

    })

    return admin.database()
        .ref('travels/' + travelId + '/locations/' + locationId + '/voting')
        .update({ votes: sumVotes })

})

Firebase功能datasnapshot不起作用

1 个答案: