Question

我正在尝试创建一个lambda function on Netlify，为此我正在使用他们的Netlify Lambda CLI。

现在，在Promises上使用async / await时遇到了一个问题，因为即使我正在使用try / catch，它也会记录UnhandledPromiseRejectionWarning。

这是一个演示：

import fetch from "node-fetch";

exports.handler = async function(event, context, callback) {
    try {
        const response = await fetch("https://api.chucknorris.io/jokes/random");
        const data = await response.json();

        callback(null, {
            statusCode: 200,
            body: data.value
        });
    } catch (err) {
        console.error(err);
    }
};

日志：

netlify-lambda: Starting server
Lambda server is listening on 9000
Hash: 533f41e1d4248894ae20
Version: webpack 4.26.1
Time: 966ms
Built at: 11/28/2018 10:59:44 PM
  Asset      Size  Chunks             Chunk Names
test.js  18.3 KiB       0  [emitted]  test
Entrypoint test = test.js
[0] external "stream" 42 bytes {0} [built]
[1] external "zlib" 42 bytes {0} [built]
[2] external "url" 42 bytes {0} [built]
[3] external "http" 42 bytes {0} [built]
[4] external "https" 42 bytes {0} [built]
[5] ./test.js + 1 modules 40.8 KiB {0} [built]
    | ./test.js 1.14 KiB [built]
    | ../node_modules/node-fetch/lib/index.mjs 39.6 KiB [built]
Request from ::1: GET /test
Response with status 200 in 685 ms.
(node:99167) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'statusCode' of undefined
    at callback (/Users/nunoarruda/Desktop/test/node_modules/netlify-lambda/lib/serve.js:22:42)
    at /Users/nunoarruda/Desktop/test/node_modules/netlify-lambda/lib/serve.js:41:21
    at process.internalTickCallback (internal/process/next_tick.js:77:7)
(node:99167) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:99167) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

相关GitHub问题：https://github.com/netlify/netlify-lambda/issues/43

当在Promises上使用异步/等待时，为什么netlify-lambda记录UnhandledPromiseRejectionWarning？我该如何解决？

Answer 1

使用新的Node.js 8.10运行时，可以使用“ async”关键字声明新的处理程序类型，或者可以直接返回promise。

在AWS文档中，v8.10支持异步/等待，并且Netlify的新默认值现在正在使用此版本。 In the AWS docs，这些示例显示了这两种新的处理程序类型，它们删除了回调的使用。我们应该使用Netlify在功能上做同样的事情。

我可以使用以下代码在本地删除错误消息，而无需使用回调：

import fetch from "node-fetch";

exports.handler = async function(event, context) {
    try {
        const response = await fetch("https://api.chucknorris.io/jokes/random");
        if (!response.ok) { // NOT res.status >= 200 && res.status < 300
            return { statusCode: response.status, body: response.statusText };
        }
        const data = await response.json();

        return {
            statusCode: 200,
            body: data.value
            // if you want to return whole json string
            // headers: { 'Content-Type': 'application/json' },
            // body: JSON.stringify(data)
        };
    } catch (err) {
        console.log(err); // output to netlify function log
        return {
            statusCode: 500,
            body: err.message // Could be a custom message or object i.e. JSON.stringify(err)
        };
    }
};

为什么在Promises上使用异步/等待时，netlify-lambda会记录UnhandledPromiseRejectionWarning？

1 个答案: