history service setup:

- Docker
- Express setup
- Route & models

Author: Shubhamjain2908

history/.dockerignore

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+node_modules

history/Dockerfile

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+FROM node:alpine
+
+WORKDIR /app
+COPY package.json .
+RUN npm install --only=prod
+COPY . .
+
+CMD [ "npm", "start" ]

history/package-lock.json

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+{
+  "name": "history",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "start": "ts-node-dev --poll src/index.ts",
+    "test": "jest --watchAll --no-cache",
+    "test:ci": "jest"
+  },
+  "jest": {
+    "preset": "ts-jest",
+    "testEnvironment": "node",
+    "setupFilesAfterEnv": [
+      "./src/test/setup.ts"
+    ]
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "@hn-hub/common": "^1.0.6",
+    "@types/express": "^4.17.6",
+    "@types/mongoose": "^5.7.27",
+    "express": "^4.17.1",
+    "express-async-errors": "^3.1.1",
+    "express-validator": "^6.6.0",
+    "mongoose": "^5.9.19",
+    "node-nats-streaming": "^0.3.2",
+    "ts-node-dev": "^1.0.0-pre.49",
+    "typescript": "^3.9.5"
+  },
+  "devDependencies": {
+    "@types/jest": "^26.0.3",
+    "@types/supertest": "^2.0.9",
+    "jest": "^26.1.0",
+    "mongodb-memory-server": "^6.6.1",
+    "supertest": "^4.0.2",
+    "ts-jest": "^26.1.1"
+  }
+}

history/package.json

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+export const natsWrapper = {
+    client: {
+        publish: jest.fn().mockImplementation((subject: string, data: string, callback: () => void) => {
+            callback();
+        })
+    }
+};

history/src/__mocks__/nats-wrapper.ts

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+import { errorHandler, NotFoundError } from '@hn-hub/common';
+import { json } from 'body-parser';
+import express from 'express';
+import 'express-async-errors';
+import { getStoriesRouter } from './routes/get-stories';
+
+const app = express();
+app.set('trust proxy', true);
+app.use(json());
+
+app.use(getStoriesRouter);
+
+app.all('*', async (req, res) => {
+    throw new NotFoundError();
+});
+
+app.use(errorHandler);
+
+export { app };
+

history/src/app.ts

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+import { ExpirationCompleteEvent } from '@hn-hub/common';
+import { Message } from 'node-nats-streaming';
+import { Story, StoryDoc } from '../../../models/stories';
+import { natsWrapper } from '../../../nats-wrapper';
+import { ExpirationCompleteListener } from '../expiration-complete-listener';
+
+const storyData = [
+    {
+        "comments": [
+            24124834
+        ],
+        "isExpired": false,
+        "title": "Mozilla lays off 250 employees while it refocuses on commercial products",
+        "url": "https://blog.mozilla.org/blog/2020/08/11/changing-world-changing-mozilla/",
+        "score": 1583,
+        "createdAt": 1597154636,
+        "user": "rebelwebmaster",
+        "storyId": 24120336
+    },
+    {
+        "comments": [
+            24135784
+        ],
+        "isExpired": false,
+        "title": "Mozilla Lifeboat",
+        "url": "https://mozillalifeboat.com",
+        "score": 1432,
+        "createdAt": 1597256213,
+        "user": "gkoberger",
+        "storyId": 24135032
+    }
+];
+
+const setup = async () => {
+    const listener = new ExpirationCompleteListener(natsWrapper.client);
+    const storyBuildObject: any[] = [];
+    storyData.forEach(story => {
+        const st = Story.build({
+            by: story.user,
+            score: story.score,
+            time: story.createdAt + '',
+            title: story.title,
+            url: story.url,
+            kids: story.comments!,
+            id: story.storyId
+        });  // building the story object
+        storyBuildObject.push(st.save());   // chainning it into the Promise array
+    });
+    // Saving all records at once
+    const stories: Array<StoryDoc> = await Promise.all(storyBuildObject);
+    const data: ExpirationCompleteEvent['data'] = {
+        stories: stories.map(e => e.storyId)
+    };
+
+    // @ts-ignore
+    const msg: Message = {
+        ack: jest.fn()
+    };
+
+    return { listener, stories, data, msg };
+};
+
+
+it('delete all the given stories', async () => {
+    const { listener, data, msg } = await setup();
+
+    await listener.onMessage(data, msg);
+
+    const updatedStory = await Story.find({});
+
+    expect(updatedStory.length).toEqual(0);
+});
+
+it('ack the message', async () => {
+    const { listener, data, msg } = await setup();
+
+    await listener.onMessage(data, msg);
+
+    expect(msg.ack).toHaveBeenCalled();
+});

history/src/events/listeners/__test__/expiration-complete-listener.test.ts

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+import { ExpirationCompleteEvent, Listener, Subjects } from '@hn-hub/common';
+import { Message } from 'node-nats-streaming';
+import { Story } from '../../models/stories';
+import { queueGroupName } from './queue-group-name';
+
+export class ExpirationCompleteListener extends Listener<ExpirationCompleteEvent> {
+    subject: Subjects.ExpirationComplete = Subjects.ExpirationComplete;
+    queueGroupName = queueGroupName;
+
+    async onMessage(data: ExpirationCompleteEvent['data'], msg: Message) {
+
+        const { stories } = data;
+        // Find all the stories
+        const storiesExists = await Story.find({ storyId: { $in: stories } });
+
+        // If no stories, throw error
+        if (!storiesExists) {
+            throw new Error('Stories not found');
+        }
+
+        // delete the expired story
+        const deletedStories = await Story.deleteMany({ storyId: { $in: stories } });
+
+        //todo: clear from the cache
+        console.log('Deleted stories: ', deletedStories);
+
+        // ack the message
+        msg.ack();
+    }
+}

history/src/events/listeners/expiration-complete-listener.ts

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+export const queueGroupName = 'stories-service';

history/src/events/listeners/queue-group-name.ts

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+import { Publisher, StoryCreatedEvent, Subjects } from '@hn-hub/common';
+
+export class StoryCreatedPublisher extends Publisher<StoryCreatedEvent> {
+    subject: Subjects.StoryCreated = Subjects.StoryCreated;
+}