Backend with NodeJS - Part 2

Posted by Abhishek on April 22, 2020

NodeJS Deep Dive

Important: Before you start reading this blog, I strongly urge you to read the Backend with NodeJS - Part 1 blog so that you will better understand the context.

As you are aware, the criminal information is currently stored in-memory within the codebase. This is not desired from a real-world perspective. In this blog, we will persist the criminal information in MongoDB rather than managing it in-memory.

1. Open the NodeJS project
2. Install the mongoose package

     npm i mongoose
   

3. Reference the mongoose package in the app.js and connect to the mongodb locally

   const mongoose = require('mongoose');
   mongoose
     .connect('mongodb://localhost/criminals')
     .then(() => console.log('Connected to database...'))
     .catch((err) => console.log('Connection to database failed.', err));
   

4. Create the schema of the Criminal object [this is like the table/document definition] and register the schema to the model class

   const criminalSchema = mongoose.Schema({
     name: {
       type: String,
     },
     type: {
       type: String,
     },
   });
   
   const Criminal = mongoose.model('Criminal', criminalSchema);
   

5. Modify the GET() and POST() implementations by referencing the Criminal model class

   app.get('/api/criminals', async (req, res) => {
     res.send(await Criminal.find());
   });
   
   app.post('/api/criminals', async (req, res) => {
     const newCriminal = new Criminal({
       name: req.body.name,
       type: req.body.type,
     });
     const result = await newCriminal.save();
     res.send(result);
   });
   

6. Run the app.js using the command ‘node app.js`
7. Open Postman and do a GET request to http://localhost:3000/api/criminals, you should get an empty array as response.
8. Now, do a POST request to http://localhost:3000/api/criminals with the request body as shown below. You should get the response back with the created criminal record that has an id value. This confirms that POST is working.
9. Now, do a GET request to http://localhost:3000/api/criminals and you should see the newly created criminal record being shown in the response.

Just to make sure that this record is persisted in MongoDB, we can check the record using MongoDB Compass.

In the next blog, we will structure this project in a much better way rather than having everything written in app.js. Stay tuned…