如何：在 node.js lambda 函数中等待/异步？

Question

我正在尝试创建一个异步 lambda 函数，使 http Get 调用无法正常工作，我相信它有处理它是异步的。如果我删除 await/async 并使其同步，我的函数将正常工作。我不确定我做错了什么。感谢您的帮助！

exports.handler = async function (event, context) {

    await setBattery();

    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

async function setBattery() {
    'use strict';

    const https = require('https');

    const options = {
        hostname: 'testsite.com',
        port: 443,
        path: '/proxy/api/setting?EM_OperatingMode=1',
        method: 'GET',
        headers: {
            'Content-Type': 'application/json',
        }
    };

    const req = https.request(options, res => {
        console.log(`statusCode: ${res.statusCode}`);

        res.on('data', d => {
            process.stdout.write(d);
        });
    });

    req.on('error', error => {
        console.error(error);
    });

    req.end();

}

Answer 1

根据 MDN 网络文档：

The async function declaration defines an asynchronous function, which returns an AsyncFunction object. An asynchronous function is a function which operates asynchronously via the event loop, using an implicit Promise to return its result. But the syntax and structure of your code using async functions is much more like using standard synchronous functions.

所以，你需要 return 一个 Promise 对象才能被你的 async function 处理（你也可以使用另一个承诺来处理它），我转换了 setBattery 到普通函数，此函数的 return 现在是将由您的处理程序处理的承诺 (exports.handler)。我还没有测试代码，但它应该可以工作。

exports.handler = async function (event, context) {

    await setBattery();

    // TODO implement
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

function setBattery() {
    'use strict';

    const https = require('https');

    const options = {
        hostname: 'testsite.com',
        port: 443,
        path: '/proxy/api/setting?EM_OperatingMode=1',
        method: 'GET',
        headers: {
            'Content-Type': 'application/json',
        }
    };

    // Return it as a Promise
    return new Promise((resolve, reject) => {

        const req = https.request(options, res => {
            console.log(`statusCode: ${res.statusCode}`);

            res.on('data', d => {
                process.stdout.write(d);

                // If successful
                resolve(d);
            });
        });

        req.on('error', error => {
            console.error(error);

            // If failed
            reject(error);
        });

        req.end();

    });

}

如何：在 node.js lambda 函数中等待/异步？

How to: await / async in a node.js lambda function?

javascript

node.js

async-await

async.js

aws-lambda