CodeIgniter Interview Questions and Answers

It is called as loosely based mvc framework because in codeigniter controller is the necessary but model and view are optional. It means we can build a website without model.

CodeIgniter can be installed with four steps that are given below:

• Download it from its download page & then unzip the package.
• Upload its files and folders on your server or localhost.
• Open application/config/config.php file and set base URL.
• If you want to use database then open application/config/database.php file and set your database credientails.
• Now it's installed

If you want to configure additional setting then you can click here

We need only PHP version 5.6 or greater than 5.6. because of potential security and performance issues.

You have to pass your helpers in array form. Here helper_1, helper_2, helper_3, helper_4 are different helpers that we want to load.

$this->load->helper(
    array('helper_1', 'helper_2', 'helper_3', 'helper_4')
);

If you want to enable hooks then you have to enabled/disabled by setting in the application/config/config.php file.

If you want to enable hooks then use this $config['enable_hooks'] = TRUE;

In CodeIgniter drivers are a very special type of Library that has a parent class and its child classes. Child classes have the access to its parent class but not their siblings. It provides an elegant syntax in your controllers file for libraries.

It can found in the system/libraries/ directory.

If we want to use a driver we have to initialize it within a controller with this given method.
$this->load->driver('class_name');

Here class_name is the name of the driver class which we want to invoke.

How we can create our own drivers in CodeIgniter.

• You can create your own driver folder in /application/libraries/
• Create your_Your_Driver_name.php file in /application/libraries/Your_Driver
• In /application/libraries/Your_Driver/drivers
  • Your_Driver_name_subclass_1.php
  • Your_Driver_name_subclass_2.php

You can use $this->db->last_query(); to display the query string.
You can use print_r($query); to display the query result.

You can create your custom 404 page with these steps. Please follow these steps one by one.

• You have to update your own created controller's class with $route['404_override'] = 'Controller_Class_Name';. You have to update this in your application/config/routes.php
• Please create your new controller "Controller_Class_Name" file in your controllers directory application/controllers/.
• Please put this code in your Controller_Class_Name.php
  
  class Controller_Class_Name extends CI_Controller {
       public function __construct() {
            parent::__construct();
       }
  
      public function index() {
           $this->output->set_status_header('404');
           $this->load->view('error_page_404');
      }
  }
• Now create your "error_page_404" view file.

You can use $this->db->insert(); to insert data in your database in Codeigniter.

You can use $lastInsertID = $this->db->insert_id(); after insert query.