A .then 在 AWS Lambda 上解决承诺后不会运行

Question

代码：

var promiseResolve, promiseReject;    

function iterateRules(rules, params, i = 0) {

    CWevents.putRule(rules[i], function(err, data) {    // This is an async function with a callback
        if (err) console.log(err); promiseReject(err)

        responses++
        params['Lambda_invoke']['SourceArns'].push(data.RuleArn)

        if(responses == rules.length){ promiseResolve("Success"); console.log("Resolved")} 
        // After two responses are confirmed, this if does run and I get the "Resolved"
    })
    i++
    if(i < rules.length){
        setTimeout( function(){
            iterateRules(params['CW_rules']['Rules'], params, i)
        }, 50)
    }
}

new Promise((resolve, reject) => {
    resolve() 
// This part is added solely for the code to make sense, it's taken out of a 
// bigger script and lots of unnecessary data is removed 
})
.then((Item) => {
            return new Promise((resolve, reject) => {
                promiseReject = reject;
                promiseResolve = resolve;
                iterateRules(params['CW_rules']['Rules'], params)
            })
}) .then((res) => {
        console.log("This ran")
   })

iterateRules 函数应该多次运行异步函数，并在获取最后一个响应时解析它调用的 Promise。 if(responses == rules.length) 确实按预期运行并在控制台中记录“已解决”。一切顺利，没有错误。

下面是这段代码的上下文，iterateRules 函数被执行，但后面的.then 没有被执行。如果我将resolve() 直接放入promise 中，它会执行。这个脚本可能有什么问题？我尝试单独运行一个看起来像这样的简单版本：

var res, rej;

function dude(){
    res()
}

new Promise((resolve, reject) => {
    res = resolve;
    dude()
}).then((dude) => {
    console.log("resolved")
})

而且它确实有效，所以我很困惑。什么可能导致问题？

Answer 1

我会让iterateRules() 返回一个承诺（因为它是异步的）。我还承诺CWevents.putRule() 函数，这样你就可以完成如下代码：

function iterateRules(rules, params) {
    return Promise.all(rules.map(rule => {
        return CWevents.putRule(rule)
    })).then((data) => {
        params['Lambda_invoke']['SourceArns'].push(data.RuleArn)
    })
}

那么您的 iterateRules 处理程序将变为：

iterateRules(rules,params).then(()=>{
    // Do something...
})