#2 connected to mongodb

backend/.env

+DB_CONN_STRING="mongodb://localhost:27017"
+DB_NAME="linksDB"
+LINKS_COLLECTION_NAME="links"
+PORT='3000'
\ No newline at end of file

backend/package.json

@@ -10,8 +10,11 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
+    "@types/node": "^18.15.0",
     "cors": "^2.8.5",
-    "express": "^4.18.2"
+    "dotenv": "^16.0.3",
+    "express": "^4.18.2",
+    "mongodb": "^5.1.0"
   },
   "devDependencies": {
     "@types/cors": "^2.8.13",

backend/src/index.ts

 import express, {Express} from 'express';
-import {linksRouter} from './routes/linksRouter';
+import {linksRouter} from './routes/links.router';
+import {connectToDatabase} from './services/database.service';
 
 const app: Express = express();
 app.use(express.json());
 app.use('/links', linksRouter);
 
-app.listen(3000, () => {
-  console.log(`Server is listening on port 3000`);
-});
+connectToDatabase()
+  .then(() => {
+    app.use('/links', linksRouter);
+    app.listen(process.env.PORT, () => {
+      console.log(`Server started at http://localhost:${process.env.PORT}`);
+    });
+  })
+  .catch((error: Error) => {
+    console.log('Database connection failed');
+    process.exit();
+  });

backend/src/models/links.ts

+import {ObjectId} from 'mongodb';
+
+export default class Link {
+  constructor(public originalUrl: string, public id?: ObjectId) {}
+}

backend/src/routes/links.router.ts

+import express, {Router, Request, Response} from 'express';
+import {ObjectId} from 'mongodb';
+import {collections} from '../services/database.service';
+import Link from '../models/links';
+
+export const linksRouter: Router = express.Router();
+
+linksRouter.get('/', (req: Request, res: Response) => {
+  try {
+    res.send('Hello');
+  } catch (error: unknown) {
+    const err = error as Error;
+    res.status(500).send(err.message);
+  }
+});
+
+linksRouter.post('/', async (req: Request, res: Response) => {
+  try {
+    const newLink = req.body as Link;
+    const result = await collections.links?.insertOne(newLink);
+    if (result) {
+      res
+        .status(201)
+        .send(`Successfully created a new link with id ${result.insertedId}`);
+    } else {
+      res.status(500).send('Failed to create a new link.');
+    }
+  } catch (err: unknown) {
+    const error = err as Error;
+    res.status(500).send(error.message);
+  }
+});

backend/src/routes/linksRouter.ts

-import express, {Router, Request, Response} from 'express';
-
-export const linksRouter: Router = express.Router();
-
-linksRouter.get('/', (req: Request, res: Response) => {
-  res.send('Hello');
-});
-
-linksRouter.post('/', (req: Request, res: Response) => {
-  res.send('Hello');
-});

backend/src/services/database.service.ts

+import * as mongoDB from 'mongodb';
+import * as dotenv from 'dotenv';
+export const collections: {links?: mongoDB.Collection} = {};
+
+export const connectToDatabase = async () => {
+  dotenv.config();
+  const client: mongoDB.MongoClient = new mongoDB.MongoClient(
+    process.env.DB_CONN_STRING
+  );
+  await client.connect();
+  const db: mongoDB.Db = client.db(process.env.DB_NAME);
+  const linksCollection: mongoDB.Collection = db.collection(
+    process.env.LINKS_COLLECTION_NAME
+  );
+  collections.links = linksCollection;
+  console.log('Connected to database');
+};

backend/src/types/environment.d.ts

+declare global {
+  namespace NodeJS {
+    interface ProcessEnv {
+      PORT: string;
+      DB_CONN_STRING: string;
+      DB_NAME: string;
+      LINKS_COLLECTION_NAME: string;
+    }
+  }
+}
+
+export {};