Codeigniter 4 REST API Tutorial with Example

REST is a defines a set of rules that makes the communication between multiple programs. We will deal with the CRUD operation using the REST API, this tutorial mainly gives precedence to HTTP methods such as GET, PUT, POST, DELETE.

This post is surely going to help all the novice developer. I will make sure that you must be aware of all the quintessential methods that are essential for knowing how to create rest web services in Codeigniter.

Read more: Build Codeigniter CRUD Application with Bootstrap

I will create a CI app, connect with database and Add, Update, delete and Show data by interacting with MySQL database. We will also have a look at Postmen to test rest API

You can extract the idea from the following video and get to know how What REST API is?

Install Codeigniter 4 Application

The first step begins with installing the CodeIgniter 4 application. This setup requires Composer Package Manager installed in your development machine.

composer create-project codeigniter4/appstarter

After installation rename appstarter folder, such as codeigniter-rest-api.

Next, head over to the project folder:

cd codeigniter-rest-api

You can skip the above process and directly download the Codeigniter application and get rid of the above process.

Turn On Error Reporting

Error reporting is necessary for application development, and it makes the development of your app more accessible. Whether we are a rookie or an experienced developer, we accidentally or unknowingly make mistakes during development.

Error reporting helps us correct the errors in real-time and also lend a hand to us to check the code with easiness.

Go to app/Config/Boot/development.php and change the display_errors value to 1 rather then 0.

Make the exact same changes in app/Config/Boot/production.php file.

ini_set('display_errors', '1');

Create Database and Table

We will store and manage the data in the database; that’s what REST API set out to do.

Open PHPMyAdmin and create a new database.

CREATE DATABASE demo;

Inside the demo database, create a new table employees where all the values will be stored using RESTful API.

CREATE TABLE employees (
    id int(11) NOT NULL AUTO_INCREMENT COMMENT 'Primary Key',
    name varchar(100) NOT NULL COMMENT 'Name',
    email varchar(255) NOT NULL COMMENT 'Email Address',
    PRIMARY KEY (id)
  ) ENGINE=InnoDB DEFAULT CHARSET=latin1 COMMENT='datatable demo table' AUTO_INCREMENT=1;
  
INSERT INTO `employees` (`id`, `name`, `email`) VALUES
(1, 'John Doe', 'john@gmail.com'),
(2, 'Vanya Hargreeves', 'vanya@gmail.com'),
(3, 'Luther Hargreeves', 'luther@gmail.com'),
(4, 'Diego Hargreeves', 'diego@gmail.com'),
(5, 'Klaus Hargreeves', 'klaus@gmail.com'),
(6, 'Ben Hargreeves', 'ben@gmail.com'),
(7, 'The Handler', 'handler@gmail.com');

Put Together Database Details

If you don’t know how to connect codeigniter with MySQL database. Then, add database details such as database name, username, password in application/config/database.php file.

public $default = [
        'DSN'      => '',
        'hostname' => 'localhost',
        'username' => 'root',
        'password' => 'root',
        'database' => 'demo',
        'DBDriver' => 'MySQLi',
        'DBPrefix' => '',
        'pConnect' => false,
        'DBDebug'  => (ENVIRONMENT !== 'development'),
        'cacheOn'  => false,
        'cacheDir' => '',
        'charset'  => 'utf8',
        'DBCollat' => 'utf8_general_ci',
        'swapPre'  => '',
        'encrypt'  => false,
        'compress' => false,
        'strictOn' => false,
        'failover' => [],
        'port'     => 3306,
	];

If anyhow you get the Codeigniter – cannot connect to MySQL database error, then change the hostname value based on your local server e.g MAMPP or XAMPP.

# MAMPP
public $default = [
  ...
     'hostname' => '/Applications/MAMP/tmp/mysql/mysql.sock',
  ...
]
# XAMPP
public $default = [
  ...
     'hostname' => '/Applications/XAMPP/xamppfiles/var/mysql/mysql.sock',
  ...
]

Create Model

Create a model file EmployeeModel.php file inside the app/Models/ directory. Place the following code inside the file to define the Model.

<?php 
namespace App\Models;
use CodeIgniter\Model;
class EmployeeModel extends Model
{
    protected $table = 'employees';
    protected $primaryKey = 'id';
    protected $allowedFields = ['name', 'email'];
}

Create REST Controller

Create a controller Employee.php in app/Controllers/ folder. In this file we will create the functions those will relentlessly handle the Create, Read, Update and Delete operations.

<?php namespace App\Controllers;
use CodeIgniter\RESTful\ResourceController;
use CodeIgniter\API\ResponseTrait;
use App\Models\EmployeeModel;

class Employee extends ResourceController
{
    use ResponseTrait;
    // all users
    public function index(){
      $model = new EmployeeModel();
      $data['employees'] = $model->orderBy('id', 'DESC')->findAll();
      return $this->respond($data);
    }
    // create
    public function create() {
        $model = new EmployeeModel();
        $data = [
            'name' => $this->request->getVar('name'),
            'email'  => $this->request->getVar('email'),
        ];
        $model->insert($data);
        $response = [
          'status'   => 201,
          'error'    => null,
          'messages' => [
              'success' => 'Employee created successfully'
          ]
      ];
      return $this->respondCreated($response);
    }
    // single user
    public function show($id = null){
        $model = new EmployeeModel();
        $data = $model->where('id', $id)->first();
        if($data){
            return $this->respond($data);
        }else{
            return $this->failNotFound('No employee found');
        }
    }
    // update
    public function update($id = null){
        $model = new EmployeeModel();
        $id = $this->request->getVar('id');
        $data = [
            'name' => $this->request->getVar('name'),
            'email'  => $this->request->getVar('email'),
        ];
        $model->update($id, $data);
        $response = [
          'status'   => 200,
          'error'    => null,
          'messages' => [
              'success' => 'Employee updated successfully'
          ]
      ];
      return $this->respond($response);
    }
    // delete
    public function delete($id = null){
        $model = new EmployeeModel();
        $data = $model->where('id', $id)->delete($id);
        if($data){
            $model->delete($id);
            $response = [
                'status'   => 200,
                'error'    => null,
                'messages' => [
                    'success' => 'Employee successfully deleted'
                ]
            ];
            return $this->respondDeleted($response);
        }else{
            return $this->failNotFound('No employee found');
        }
    }
}

The methods below deal with a particular task with RESTful API, let me enumerate all the functions performed by each method that we defined in the controller.

• index() – Get’s all the records from the database.
• create() – It propels an employee record into the database table.
• show() – It gets a single employee record from the database.
• update() – It updates the user record into the database.
• delete() – It deletes an employee record the database.

Create REST API Route

To sustain the impetus of data between client and server we need API, to access the api we also need to define the route in CI.

Open the app/Config/Routes.php file, and look for the following code.

$routes->get('/', 'home::index');

Next, remove the above line of code and add the given line of code.

$routes->resource('employee');

TEST Codeigniter RESTful API

Eventually, we have gone through every imperative. Now, Its time to start the application using the following command:

php spark serve

Let us test out the REST API that gets all the user records from the database.

GET All Records

http://localhost:8080/employee

GET Single Record

http://localhost:8080/employee/4

Update Record

http://localhost:8080/employee/4

Add Record in Database

http://localhost:8080/employee

Delete Record

http://localhost:8080/employee/5