我如何獲取數據快照，然后在Firebase Cloud Functions http請求中更新數據庫

Question

我正在嘗試在雲功能的HTTPS請求中獲取Firebase實時數據庫的數據快照，然后將來自查詢的值添加到快照值，然后再次將其設置為數據庫。

這是我的代碼。

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);
    })
})

這是部署代碼時終端中的錯誤。

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

如何獲取數據庫快照並再次寫入？

Answer 1

這些錯誤消息對Ganesh很有幫助，請閱讀它們兩者...

18:70 warning Unexpected function expression prefer-arrow-callback

是警告，表示您應該使用ES6箭頭函數語法而不是帶有“ function ”一詞的老式語法：

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

然后是實際的錯誤...

18:70 error Each then() should return a value or throw promise/always-return

告訴您，每次使用.then() ，內部函數都需要返回某些內容。

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;
    })