Make API in Codeigniter

Introduction

CodeIgniter provide auto initialized Output class which is very useful for creating API and differents type of documents output like .pdf, .csv, .image, etc...

NOTE :- Codeigniter default document type is HTML change it to application/json, API must be required type of json

create protected api

This API not accessible for public user, authentication is required

/***************************
this is protected api this is not accessible if you are not loged in
***************************/
public function protectedapi(){
  if($this->session->userdata('logged_in')){
    //this section only accessible when user loged in
    $this->output->set_output(json_encode(array('status'=>true,'msg'=>'Access allowed')));
  }else{
    $this->output->set_output(json_encode(array('status'=>true,'msg'=>'Access denied')));
  }
}

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create the new controller with name API

<?php

defined('BASEPATH') OR exit('No direct script access allowed');

class Api extends CI_Controller {
  //default value
  private $login_credential;

  function __construct() {
    parent::__construct();
    //for user authentication
    $this->load->library('session');

    //set page header type Json as default
    $this->output->set_content_type('application/json');
    //default credentials for user login
    $this->login_credential = array(
        'username'=>'admin',
        'password'=>'test@123',
        'email'=> 'domain@test.com'
      );
  }
}
?>

log in user API for allow access of some private data for perticular user

/*****************************
login user
@required : username and password via post method only
@return user data if login successfull otherwise error message
****************************/
public function login(){
  $username=$this->input->post('username');
  $password=$this->input->post('password');
  if($username && $password){
    //check username and password
    if($this->login_credential['username']==$username && $this->login_credential['password']==$password){
      //set user data to store in session
      $userdata = array(
        'username'  => $this->login_credential['username'],
        'email'     => $this->login_credential['email'],
        'logged_in' => true
      );
      //set session
      $this->session->set_userdata($userdata);
      //display log in successfull msg
      $this->output->set_output(json_encode(array('status'=>true,'msg'=>'log in successfully','data'=>$userdata))); 
    }else{
      //wrong username or password
      $this->output->set_output(json_encode(array('status'=>false,'msg'=>'invalid Username or password'))); 
    }
  }else{
    //when username and password not set
    $this->output->set_output(json_encode(array('status'=>false,'msg'=>'provide Username and password')));
  }
}

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Retrieve some data from API add following function in API controller

/*****************************
@return all events
****************************/
public function getallevents(){
  //get data from model
  $events = array(
    array('Event 1', '2015-04-03'),
    array('Event 2', '2015-04-03'),
    array('Event 3', '2015-06-16'),
    array('Event 4', '2015-06-29'),
    array('Event 5', '2015-07-04'),
    array('Event 6', '2015-12-25'),
    array('Event 7', '2016-01-01')
  );
  $this->output->set_output(json_encode(array('status'=>true,'events'=>$events)));
}

Postman view enter image description here

user log out api to destroy the session of loged in user

/***************************
log out user
***************************/
public function logout(){
  //delete all session
  session_destroy();
  $this->output->set_output(json_encode(array('status'=>true,'msg'=>'log Out successfully')));
}

enter image description here