Designing a better architecture for a Node.js API
Tags: node, express, mongodb
Published: 2019-11-02 22:07:12

---
title: Designing a better architecture for a Node.js API
published: true
description: Designing a better architecture for a Node.js API
tags: Node.js, Express, MongoDB
cover_image: https://thepracticaldev.s3.amazonaws.com/i/jvss5tgpf0dcsuwjhbqg.jpg
---

Some time ago I made a post about [creating a Fullstack project with Node.js, React.js, and MongoDB](https://dev.to/pacheco/my-fullstack-setup-node-js-react-js-and-mongodb-2a4k). This is a very cool starter project that could help us get up and running with the basics.

But implementing a better architecture is very important, especially if you have a big project and you are working with a large team. This will help you develop and maintain easily your project.

So the objective of this post is to share my current API architecture and the way I found to create a better structure, applying design patterns and clean code.

Let's dive into code.

![](https://media.giphy.com/media/xUPGciLiI07yUU7D0s/giphy.gif)

First of all, let's create our work folder and the initial files.

```bash
$ mkdir node-starter
$ cd node-starter
$ touch index.js
$ npm init -y
```

##Creating the structure

Now, let's create the base folders for the project

```bash
 $ mkdir config src src/controllers src/models src/services src/helpers
```

##Add dependencies


For this project, we are going to use Express and MongoDB, so let's add our initial dependencies.

```bash
$ npm install --save body-parser express mongoose mongoose-unique-validator slugify
```

##Add DEV dependencies

As we want to be able to use the latest ES6 syntax in this project, let's add babel and configure it.

```bash
npm i -D @babel/node @babel/core @babel/preset-env babel-loader nodemon
```
Here we also added nodemon as a dev dependency to run and test the project easily.


##Setting up babel

In the main folder, create a file called .babelrc with the following code:


```javascript
{
  "presets": [
    "@babel/preset-env"
  ]
}
```

Now go over to your package.json and add the following scripts

```json
"scripts": {
    "start": "babel-node index.js",
    "dev:start": "clear; nodemon --exec babel-node index.js"
 }
```


##Create the server

Under config folder, create a file called server.js with the following code

```javascript
import express from "express";
import bodyParser from "body-parser";
const server = express();

server.use(bodyParser.json());

export default server;
```

Now let's import our server config into our index.js file:

```javascript
import server from './config/server';

const PORT = process.env.PORT || 5000;
server.listen(PORT, () => {
  console.log(`app running on port ${PORT}`);
});
```

At this point, you should be able to run your server with the following script:

```bash
$ npm run dev:start
```

And you should get a response like this:

```bash
[nodemon] 1.19.4
[nodemon] to restart at any time, enter `rs`
[nodemon] watching dir(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `babel-node index.js`
app running on port 5000
```


#Setting up the Database

Now let's set up our database.
<b>For this, you must have MongoDB up and running in your local machine.</b>

Under config, add the file database.js

```javascript
//database.js

import mongoose from "mongoose";

class Connection {
  constructor() {
    const url =
      process.env.MONGODB_URI || `mongodb://localhost:27017/node-starter`;
    console.log("Establish new connection with url", url);
    mongoose.Promise = global.Promise;
    mongoose.set("useNewUrlParser", true);
    mongoose.set("useFindAndModify", false);
    mongoose.set("useCreateIndex", true);
    mongoose.set("useUnifiedTopology", true);
    mongoose.connect(url);
  }
}

export default new Connection();


```

Here we are creating a singleton instance of our database by exporting a new Connection. This is automatically handled by node when you export it like this and it makes sure that you are only going to have one single instance of this class in your application. 

And now, import it right in the beginning of your index.js file.

```javascript
//index.js
import './config/database';
//...
```


##Create a model


Now let's create our first model.
Under src/models, create a file called Post.js with the following content.

```javascript
//src/models/Post.js
import mongoose, { Schema } from "mongoose";
import uniqueValidator from "mongoose-unique-validator";
import slugify from 'slugify';

class Post {

  initSchema() {
    const schema = new Schema({
      title: {
        type: String,
        required: true,
      },
      slug: String,
      subtitle: {
        type: String,
        required: false,
      },
      description: {
        type: String,
        required: false,
      },
      content: {
        type: String,
        required: true,
      }
    }, { timestamps: true });
    schema.pre(
      "save",
      function(next) {
        let post = this;
        if (!post.isModified("title")) {
          return next();
        }
        post.slug = slugify(post.title, "_");
        console.log('set slug', post.slug);
        return next();
      },
      function(err) {
        next(err);
      }
    );
    schema.plugin(uniqueValidator);
    mongoose.model("posts", schema);
  }

  getInstance() {
    this.initSchema();
    return mongoose.model("posts");
  }
}

export default Post;

```

##Create our services

Let's create a Service class that is going to have all the common functionalities for our API, making it available for other services to inherit them.
Create a file Service.js under src/services folder;

```javascript
//src/services/Service.js

import mongoose from "mongoose";

class Service {
  constructor(model) {
    this.model = model;
    this.getAll = this.getAll.bind(this);
    this.insert = this.insert.bind(this);
    this.update = this.update.bind(this);
    this.delete = this.delete.bind(this);
  }

  async getAll(query) {
    let { skip, limit } = query;

    skip = skip ? Number(skip) : 0;
    limit = limit ? Number(limit) : 10;

    delete query.skip;
    delete query.limit;

    if (query._id) {
      try {
        query._id = new mongoose.mongo.ObjectId(query._id);
      } catch (error) {
        console.log("not able to generate mongoose id with content", query._id);
      }
    }

    try {
      let items = await this.model
        .find(query)
        .skip(skip)
        .limit(limit);
      let total = await this.model.count();

      return {
        error: false,
        statusCode: 200,
        data: items,
        total
      };
    } catch (errors) {
      return {
        error: true,
        statusCode: 500,
        errors
      };
    }
  }

  async insert(data) {
    try {
      let item = await this.model.create(data);
      if (item)
        return {
          error: false,
          item
        };
    } catch (error) {
      console.log("error", error);
      return {
        error: true,
        statusCode: 500,
        message: error.errmsg || "Not able to create item",
        errors: error.errors
      };
    }
  }

  async update(id, data) {
    try {
      let item = await this.model.findByIdAndUpdate(id, data, { new: true });
      return {
        error: false,
        statusCode: 202,
        item
      };
    } catch (error) {
      return {
        error: true,
        statusCode: 500,
        error
      };
    }
  }

  async delete(id) {
    try {
      let item = await this.model.findByIdAndDelete(id);
      if (!item)
        return {
          error: true,
          statusCode: 404,
          message: "item not found"
        };

      return {
        error: false,
        deleted: true,
        statusCode: 202,
        item
      };
    } catch (error) {
      return {
        error: true,
        statusCode: 500,
        error
      };
    }
  }
}

export default Service;

```


![](http://giphygifs.s3.amazonaws.com/media/JSueytO5O29yM/giphy.gif)

Ok, this seems a lot of code.

In this service, we created the main functionality (a basic CRUD) for our application, adding functions to get, insert, update and delete items.

Now, let's create our Post service and inherit all this functionality we just created.
Under src/services, create a file PostService.js with the following content:

```javascript
//src/services/PostService
import Service from './Service';

class PostService extends Service {
  constructor(model) {
    super(model);
  }
};

export default PostService;


```

It is as simple as that, it inherits all the functionality we created in our main Service.js file and it can be repeated across your API for all the other endpoints.


#Create the controllers

We are going to follow the same principle we had while creating our services, here we are going to create a main Controller.js file that will have all the common functionalities and make the other controllers inherit it.

Create a file Controller.js under src/controllers and add the following code:

```javascript
//src/controllers/Controller.js

class Controller {

  constructor(service) {
    this.service = service;
    this.getAll = this.getAll.bind(this);
    this.insert = this.insert.bind(this);
    this.update = this.update.bind(this);
    this.delete = this.delete.bind(this);
  }

  async getAll(req, res) {
    return res.status(200).send(await this.service.getAll(req.query));
  }

  async insert(req, res) {
    let response = await this.service.insert(req.body);
    if (response.error) return res.status(response.statusCode).send(response);
    return res.status(201).send(response);
  }

  async update(req, res) {
    const { id } = req.params;

    let response = await this.service.update(id, req.body);

    return res.status(response.statusCode).send(response);
  }

  async delete(req, res) {
    const { id } = req.params;

    let response = await this.service.delete(id);

    return res.status(response.statusCode).send(response);
  }
  
}

export default Controller;
```

Now, let's create a PostController file under src/controllers

```javascript
//src/controllers/PostController.js

import Controller from  './Controller';
import PostService from  "./../services/PostService";
import Post from  "./../models/Post";
const postService = new PostService(
  new Post().getInstance()
);

class PostController extends Controller {

  constructor(service) {
    super(service);
  }
  
}

export default new PostController(postService);

```

Here, we are importing the desired service and model and we are also creating an instance of our Post service passing a Post model instance to its constructor.



#Create the routes

Now it's time to create the routes for our API.

Under the config folder, create a file routes.js

```javascript
//config/routes.js
import PostController from './../src/controllers/PostController';

export default (server) => {

  // POST ROUTES
  server.get(`/api/post`, PostController.getAll);
  server.post(`/api/post`, PostController.insert)
  server.put(`/api/post/:id`, PostController.update);
  server.delete(`/api/post/:id`, PostController.delete);

}
```

This file imports the Post controller and map the functions to the desired routes.

Now we have to import our routes into our server.js file right after our body parser setup, like so:

```javascript
//config/server.js
//...
import setRoutes from "./routes";
setRoutes(server);
//...
```

Et Voila!!
![](http://giphygifs.s3.amazonaws.com/media/Mp4hQy51LjY6A/giphy.gif)

At this point, you should be able to make requests to all the routes created, so let's test it.


Make a POST request for the route /api/post with the following json body:
Here you can use an API client like [Postman](https://www.getpostman.com/) or [Insomnia](https://insomnia.rest/download/) to this task

```json
{
	"title": "post 1",
	"subtitle": "subtitle post 1",
	"content": "content post 1"
}
```

You should get something like this:

```json
{
  "error": false,
  "item": {
    "_id": "5dbdea2e188d860cf3bd07d1",
    "title": "post 1",
    "subtitle": "subtitle post 1",
    "content": "content post 1",
    "createdAt": "2019-11-02T20:42:22.339Z",
    "updatedAt": "2019-11-02T20:42:22.339Z",
    "slug": "post_1",
    "__v": 0
  }
}
```

##Conclusion

There are lots of ways to design the architecture of an API, and the goal is always to have a cleaner and reusable code, don't repeating yourself and helping others to work along easily, plus it will also help yourself with maintenance and adding new functionalities.

![](https://media.giphy.com/media/3o7abKhOpu0NwenH3O/giphy.gif)

You can find the [source code here](https://github.com/thisk8brd/node-starter)


Hope you may find it useful.
Bye!