如何在firebase cloud函数http请求中获取数据快照并更新数据库

Question

我尝试在云函数的HTTPS请求中取firebase实时数据库的数据shapshot，然后将来自查询的值添加到快照值中，再将其设置为database。

exports.addCredits = functions.https.onRequest((req, res)=>{
    console.log(req.query.UserID);
    var credits = req.query.amount
    var userId = req.query.UserID

    return admin.database().ref('/Users/' + userId).once('value').then(function(snapshot) {
        var userPoints = snapshot.val().Credit
        const databaseRef = admin.database().ref("Users").child(userId+"/Credit")
        res.send("Your Credits  "+ credits + " And User ID " + userId + " user points" + userPoints);
        var total = credits + userPoints
        databaseRef.set(total);
    })
})

在部署代码时，终端出现错误。

18:70  warning  Unexpected function expression              prefer-arrow-callback
18:70  error    Each then() should return a value or throw  promise/always-return

如何获取数据库的快照并再次写入它？

Answer 1

这些错误信息很有帮助，Ganesh，阅读它们两个...

18:70警告意外函数表达式首选-箭头-回调

是一个警告，说明您应该使用ES6箭头函数语法，而不是带有“function”一词的老式语法：

18:70 error Each then（）应该返回一个值或抛出promise/always-return

告诉您每次使用.then()时，内部函数需要返回一些内容。

return admin.database().ref('/Users/' + userId).once('value').then( snapshot => {
        var userPoints = snapshot.val().Credit
        const databaseRef = admin.database().ref("Users").child(userId+"/Credit")
        res.send("Your Credits  "+ credits + " And User ID " + userId + " user points" + userPoints);
        var total = credits + userPoints
        databaseRef.set(total);
        // You are inside of a .then() block here...
        // you HAVE return SOMETHING...
        // if you want, you could do:   return databaseRef.set(total);
        // or even just:   return true;
    })