我对AWS Lambda函数中使用的promise和异步任务有点混淆。
我已经整理了一个小程序,其中包含了我尝试网络抓取给定网址的知识。但是,当我使用无效地址运行时,程序挂起而不是返回我的无效请求。当url有效时,它运行没有失败,但我预计不会如预期的那样。
如果有人可以帮助我理解我的错误配置在以下代码中的位置,或者如果我以完全错误的方式处理承诺,那将非常感激。
const request = require('request');
const await = require('await');
const async = require('async');
exports.handler = async function(event, context, cb) {
var domain = "https://google.com"
var uri = "/non/existant/path"
var url = `${domain}${uri}`
var webpage = await getWebpage(url)
cb(null, 'success')
}
function getWebpage(url) {
console.log(`Connecting to '${url}'`)
return new Promise(function (resolve, reject) {
request(url, function(error, response, body) {
console.log(response.statusCode)
if (response.statusCode != 200) {
console.log(`ERROR: ${response.statucCode}`);
reject(`See logs for details`);
}
console.log('Connected! Saving contents')
resolve(body);
});
});
}
答案 0 :(得分:0)
您的代码看起来有三个问题。首先,async
和await
不是库,它们是关键字(如Jonas所提到的)。第二,真正不清楚为什么要将回调传递给返回promise(exports.handler
)的函数;您正在构建的API可能会让您感到困惑。
第三,直接回答您关于无效网址无效的问题:在尝试检查响应代码和/或正文之前,您没有检查错误的响应。请尝试下面的代码。
const request = require('request')
exports.handler = async function(event, context, cb) {
var domain = "https://google.com"
var uri = "/non/existant/path"
var url = `${domain}${uri}`
var webpage = await getWebpage(url)
cb(null, 'success') // <- It's unclear why you'd want to do this.
}
function getWebpage(url) {
console.log(`Connecting to '${url}'`)
return new Promise(function (resolve, reject) {
request(url, function(error, response, body) {
// First, check for an error.
if (error) return reject(error)
// Next, check the status code.
if (response.statusCode != 200) {
console.log(`ERROR: ${response.statusCode}`);
return reject(new Error(response.statusCode));
}
// Okay, now resolve if the above checks were good.
console.log('Connected! Saving contents')
resolve(body)
})
})
}