在无服务器（nodejs 8）中调用 lambda 的正确方法

Question

我有 read some guides 并且因为我是菜鸟而且也很愚蠢，所以我仍然看不到在 serverless 中正确地在本地调用 Lambda 的方法。

我首先在下面实现了一个非常基本的 lambda 函数：

'use strict';

const AWS = require('aws-sdk');
const Politician = require('../model/politician.js');

const dynamoDb = new AWS.DynamoDB.DocumentClient();

module.exports.put = async (event, context, callback) => {

    const requestBody = new Politician(event.body);
    let response;

    console.log('did we get this far?');

    submit(requestBody)
        .then(res => {
            response = {
                statusCode: 200,
                body: JSON.stringify({
                    message: `Successfully submitted politician with name ${requestBody.name}`,
                    politicianId: res.id
                })
            }
                .catch(err => {
                    console.log(err);
                    response = {
                        statusCode: 500,
                        body: JSON.stringify({
                            message: `Unable to submit candidate with email ${requestBody.name}`
                        })
                    }
                });
        });
};

const submit = politician => {
    console.log('submitting politician: ' + politician.name);

    return new Promise((resolve, reject) => {
        if (politician) {
            resolve(politician);
        } else {
            reject(new Error('it all went bad!'));
        }
    });
};

我还没有使用 DynamoDB，但我想使用它（我只需要先进行基本调用）。

然后我设置了一个非常简单的 Jest 单元测试，它调用上面的 lambda 函数：

'use strict';
const fs = require('fs');
const { promisify } = require('util');
const readFile = promisify(fs.readFile);

const AWS = require('aws-sdk');
const options = {
    region: 'localhost',
    endpoint: 'http://localhost:8000'
};
AWS.config.update(options);
const eventStub = require('../events/graeme.richardson.json');
const { lambda } = readFile('../functions/coxon-put-politician');


describe('Service politicians: mock for successful operations', () => {

    test('Replies back with a JSON response', () => {

        const event = eventStub;
        const context = {};

        const result = lambda.put(event, context);

        result
            .then(data => {
                expect(data).toBeFalsy();
            })
            .catch(e => {
                expect(e).toBe('me');
            });

    });
});

我尝试了各种方法来调用 const result = lambda.put(event, context); 调用 lambda，只使用它的名称，将对象重铸为函数，以及大量其他方法，但我得到的只是错误的变体：

TypeError: Cannot read property 'put' of undefined

      37 |         const context = {};
      38 | 
    > 39 |         const result = lambda.put(event, context);
         |                               ^
      40 | 
      41 |         result
      42 |             .then(data => {

      at Object.put (functions-test/coxon-put-politician.test.js:39:31)

或

TypeError: lambda is not a function

      37 |         const context = {};
      38 | 
    > 39 |         const result = lambda(event, context);
         |                        ^
      40 | 
      41 |         result
      42 |             .then(data => {

      at Object.lambda (functions-test/coxon-put-politician.test.js:39:24)

我觉得我只是错过了我链接到的指南没有说的一点信息。有谁知道如何让它工作？

我希望很明显，我最终会在 AWS Lambda 上瞄准 node.js 8.1。

谢谢

Answer 1

感谢您查看此@Chetan Ranpariya，是的，这似乎是问题所在。不知道为什么很多帖子都推荐promisify() - 我猜肯定有一种方法可以奏效，但我只是没有魔力。有效的 lambda 代码是：

'use strict';

const AWS = require('aws-sdk');
const Politician = require('../model/politician.js');

module.exports.put = async (event, context) => {

    const requestBody = new Politician(event.body);
    let response;

    submit(requestBody)
        .then(res => {
            response = {
                statusCode: 200,
                body: JSON.stringify({
                    message: `Successfully submitted politician with name ${requestBody.name}`,
                    politicianId: res.id
                })
            }

        });
};

const submit = politician => {
    console.log('submitting politician: ' + politician.name);

    return new Promise((resolve, reject) => {
        if (politician) {
            resolve(politician);
        } else {
            reject(new Error('it all went bad!'));
        }
    });
};

它的 Jest 测试是：

'use strict';
const AWS = require('aws-sdk');
const options = {
    region: 'localhost',
    endpoint: 'http://localhost:8000'
};
AWS.config.update(options);
const eventStub = require('../events/graeme.richardson.json');
const lambda = require('../functions/coxon-put-politician');


describe('Service politicians: mock for successful operations', () => {

    test('Replies back with a JSON response', () => {

        const event = eventStub;
        const context = {};

        const result = lambda.put(event, context);

        result
            .then(data => {
                expect(data).toBeTruthy();
            })

    });
});