Top 26 Codeigniter Interview Questions to Test Your Skills

Codeigniter is an open-source framework for developing websites on PHP. It is loosely based on the MVC pattern, and it is easy to use compared to other PHP frameworks.

CodeIgniter contains libraries, a simple interface, and a logical structure to access these libraries, plug-ins, helpers, and some other resources which solve the complex functions of PHP more easily maintaining high performance.

The Hook is a feature in CodeIgniter that provides a way to change the inner working of the framework without hacking the core files. It facilitates you to execute a script with a particular path within the CodeIgniter. Usually, it is defined in the application/config/hooks.php file.

CodeIgniter security methods help to create a secure application and process input data. The methods are given below:

• XSS filtering
• CSRF (Cross-site Request Forgery)
• Class reference

A CSRF attack forces a logged-on victim’s browser to send a forged HTTP request, including victim’s session cookie and other authentication information, to a web application.

For example, suppose you have a site with a form. An attacker could create a bogus form on his site. This form could contain hidden inputs and malicious data. This form is not sent to the attacker’s site, in fact, it comes to your site. Thinking that the form is genuine, your site process it.

Now suppose that the attacker’s form point towards the deletion form in your site. If a user is logged in and redirected to the attacker’s site and then performs the search, his account will be deleted without knowing him. That is the CSRF attack.

XSS stands for cross-site scripting. Codeigniter contains a cross-site scripting hack prevention filter. The XSS filter targets methods to trigger JavaScript or other types of suspicious code. If it detects anything, it converts the data to character entities.

There are many purposes for which the URL routes are configured.

1. To improve the number of page visits.
2. To hide the code complexities from the user.

Followings are Different types of hook points in Codeigniter:

• post_controller_constructor
• pre_controller
• post_sytem
• pre_system
• cache_override
• display_override
• post_controller

To connect more than one database simultaneously, do the following,

$db1 = $this->load->database('group_one', TRUE);

$db1 = $this->load->database('group_two', TRUE);

Inhibitors are basically Error handling classes that are associated with CodeIgniter and these are implemented using different PHP functions.

To extend the native input class in CodeIgniter, you have to build a file named application/core/MY_Input.php and declare your class with

Class MY_Input extends CI_Input {

}

In the default URL pattern, there are four main components in CodeIgniter. First, we have the server name followed by the controller class name. Then, we have the controller function name and at the end, there are function parameters. We can access the CodeIgniter using the URL helper.

Syntax- http://servername/controllerName/controllerFunction/parameter1/parameter2.

$this->config->item(‘variable name’);

$this->session->unsetuserdata(‘somename’);;

The CodeIgniter provides a different set of libraries and these are useful with the continues improvements and support of the application and also its corresponding enhancements. This is mainly located in the system->library section. There are different types of methods that can be used to create a library.

1. The process to create a whole new library.
2. The process to replace the native library.
3. The process to extend the native library.

These are a particular type of library that has a parent class and many child classes. These child classes have access to the parent class, but not to their siblings. Drivers are found in the system/libraries folder.

We can auto load model like this:

$autoload[‘model’] = array(array(‘usersmodel’, ‘users’), array(‘newsmodel’, ‘news’), ‘categorymodel’);

We can use this:

$this->db->order_by(‘id’,’RANDOM’);

Codeigniter was developed by EllisLab Inc.

The reason behind this is we do not need to follow a strict MVC pattern while creating an application. We can also able to build with a model-only view and controllers are enough to build an application.