谷歌云功能承诺执行并返回

Question

我有一个谷歌云维护功能，我想运行它来更新Firebase实时数据库。代码非常直接，但由于某些原因，执行在所有代码运行之前就完成了。我怀疑我的等待呼叫没有按预期处理，因为我错过了使用.oce((？

exports.setUserLimits = functions
.region('europe-west1')
.database
.ref('/NO-TRIGGER')
.onCreate(async (snapshot, context) => {
let myPromises = []
const userNodeSnap = await database.ref('users').once('value')
console.log('numChildren', userNodeSnap.numChildren())
userNodeSnap.forEach(async (userSnap) => {
console.log('Process user', userSnap.key)
const userData = userSnap.val()
//Set user limits
const limits = {items:10, logins:1}
console.log('New limits', limits)
myPromises.push(userSnap.ref.update({limits}))
})
// Execute all promises
console.log('myPromises lenght', myPromises.length)
return Promise.all(myPromises)
.then(()=>{
return Promise.resolve()
})
.catch((err)=>{
console.error('Could not execute all promises', err)
// Show must go on!
return Promise.resolve()
})
})

从谷歌云功能注销

setUserLimits Function execution started
numChildren 4
Process user 1234567890
myPromises lenght 0
Function execution took 416 ms, finished with status: 'ok'
New limits {items:10, logins:1}

执行提前结束，导致只更新一条记录。

将最后一行替换到下面会生成相同的结果

await Promise.all(myPromises)

/K

Answer 1

如果我们看看这段代码：

userNodeSnap.forEach(async (userSnap) => {
console.log('Process user', userSnap.key)
const userData = userSnap.val()
//Set user limits
const limits = {items:10, logins:1}
console.log('New limits', limits)
myPromises.push(userSnap.ref.update({limits}))
})

我们看到它具有逻辑形式：

someArray.forEach(async function(element) {
// do something
});

基本上，forEach函数调用之后的代码可以在aray的每个元素的处理完成之前执行。