REST API with Express

API service is a back-end technique that providing clients database information with interface. Express is a npm module for us to create API services quickly.

Brief

Basic API

CRUD-like approach: GET POST PUT DELETE with HTTP request

  app.get('/api',(req,res)=>{
    res.send('API is running');
  });

When you type localhost/api on the browser, you will see a sentence ‘API is running’ in a white page

If you are not familiar with this basic API setup, please go to my Basic API project. It will give you a full explanation of REST API and how it works.

If you know how to make regular API, let’s keep going 🔥🔥🔥

Get Start

Architecture

model
controller
route

Step 1 - Model

First, you need to design the purpose of your API service.

For example, I choose transportation as my topic. So I defined the class for them.

e.g. Bus 🚌🚏

Item	Detail
name	Name of transportation
capacity	How many people hold by the bus
enabled	Availability (service in maintenance or other issue)

module.exports = (sequelize, Sequelize) => {
    const Transportation = sequelize.define("transportation", { // "transportation" will be your table name
        name: {
            type: Sequelize.STRING
        },
        capacity: {
            type: Sequelize.STRING
        },
        enabled: {
            type: Sequelize.BOOLEAN
        }
    });

    return Transportation;
};

Step 2 - DB Connection

After making this module, export it for other files in this project.

Make the configuration with MySQL connection and use Sequelize ORM that you don’t need to write query to do normal CRUD action.

npm install sequelize mysql2 --save

const sequelize = new Sequelize('database', 'username', 'password', {
  host: 'localhost',
  dialect: 'mysql'
});

Step 3 - Controller

Then use Sequelize CRUD methods

exports.create (POST)
exports.findAll (GET)
exports.findOne (GET with name)

exports.create = (req, res) => {
    // validation
    if (!req.body.name) {
        res.status(400).send({
            message: "Name cannot be empty!"
        });
        return;
    }

    // create the transportation item
    const item = {
        name: req.body.name,
        capacity: req.body.capacity,
        enabled: req.body.enabled ? req.body.enabled : false
    };

    // DB Action: save the item to table
    Transportation.create(item)
        .then(data => {
            res.send(data);
        })
        .catch(err => {
            res.status(500).send({
                message:
                    err.message || "Some error occurred while creating the transportation."
            });
        });
};

exports.findAll = (req, res) => {
    const name = req.query.name;
    var condition = name ? { name: { [Op.like]: `%${name}%` } } : null;

    Transportation.findAll({ where: condition })
        .then(data => {
            res.send(data);
        })
        .catch(err => {
            res.status(500).send({
                message:
                    err.message || "Some error occurred while retrieving transportation."
            });
        });
};

exports.findOne = (req, res) => {
    const name = req.params.name;

    Transportation.findByPk(name)
        .then(data => {
            res.send(data);
        })
        .catch(err => {
            res.status(500).send({
                message: "Error retrieving Transportation with name=" + name
            });
        });
};

Step 4 - Setup routes

module.exports = app => {
    const transportation = require("../controllers/transportation.controller");

    var router = require("express").Router();

    router.post("/", transportation.create);
    router.get("/", transportation.findAll);
    router.get("/:name", transportation.findOne);

    app.use('/api/transportation', router);
};

Test your API with Postman

See more on my GitHub project: https://github.com/keithchan1218/rest-api-mysql

Credit: bezkoder

Tags: API