Codeigniter Interview Questions

Codeigniter is an open-source framework for web applications on PHP. It is loosely based on the MVC pattern and is similar to CakePHP.

A list of the most prominent features of CodeIgniter:

• It is an open-source framework and free to use.
• It is extremely light weighted.
• It is based on Model View Controller (MVC) pattern.
• It has full-featured database classes and support for several platforms.
• It is extensible. You can easily extend the system by using your own libraries, helpers, etc.
• Excellent documentation.

from the technical point of view, CodeIgniter is dynamically instantiated (light-weighted), loosely coupled (components rely very less on each other), and has component singularity (each class and function are narrowly focused towards their purpose).

To load models in controller functions, use the following function:

$this->load->model(ModelName);

To connect the database manually use the following syntax,

$this->load->database();

View folder contains all the markup files like header, footer, sidebar, etc. They can be reused by embedding them anywhere in the controller file. They cant be called directly, they have to be loaded in the controllers file.

The view cant is accessed directly. It is always loaded in the controller file.

The following function is used to load a view page:

$this->load->view(page_name);

A controller is the intermediary between models and views to process the HTTP request and generates a web page. It is the center of every request on your web application.

Instead of using the query-string approach, it uses a segment-based approach.

Its structure is as follows,

abc.com/class/function/ID

class represents the controller class that needs to be invoked.

a function is a method that is called.

ID is an additional segment that is passed to controllers.

By default controller always calls the index method. If you want to call a different method, then write it in the controllers file and specify its name while calling the function.

The second segment of URI determines which method is being called. If you want to override it, you can use the _remap() method. The _remap method always gets called even if URI is different. It overrides the URI

Helpers are the group of functions in a particular category that assist you to perform specific functions.

In CodeIgniter, there are many helpers like:

URL Helpers: helping in creating links.

Text Helpers: perform various text formatting routines.

Cookies Helpers: set and read cookies.

To load the helper file, use the following command:

$this->load->model(ModelName);

CodeIgniter provides a rich set of libraries. It is an essential part of CodeIgniter as it increases the developing speed of an application. It is located in the system/library.

It can be loaded as follows,

$this->load->library(class_name);

There are three methods to create a library:

• Creating an entirely new library
• Extending native libraries
• Replacing native libraries

Version: 3.0.5,
Date January 13, 2016

PHP

To load multiple helper files, specify them in an array,

1. $this->load->helper(
2. array(helper1, helper2, helper3)
3. );

1. CodeIgniter provides a rich set of libraries. It is an essential part of CodeIgniter as it increases the developing speed of an application. It is located in the system/library.

It can be loaded as follows,

It should be placed in the application/libraries folder.

Yes, we can add some extended functionality to a native library by adding one or two methods. It replaces the entire library with your version. So it is better to extend the class. Extending and replacing are almost identical with only the following exceptions.

• The class declaration must extend the parent class.
• The new class name and filename must be prefixed with MY_.

For example, to extend it to the native Calendar, create a file MY_Calendar.php in the application/libraries folder. Your class declared as class MY_Calendar extends CI_Calendar}

You have to build a file name application/core/MY_Input.php and declare your class with Class MY_Input extends CI_Input {}to extend the native input class in CodeIgniter.

Routing is a technique by which you can define your URLs according to the requirement instead of using the predefined URLs. Routes can be classified in two ways, either using wildcards or Regular Expressions.

Wildcards

There are two types of wildcards:

• : num- series containing only numbers matched.
• : any- series containing only characters matched.

Regular Expression

Regular expressions are also used to redirect routes.

You can create your regular expression to run your URL.

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

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

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.

To enable hook, go to application/config/config.php/ file and set it TRUE as shown below,

Static resources allow you to add the content that you want to reference on the visualforce page, which includes things like images, Javascript, archives, CSS files, etc. The maximum size of a static resource of an organization is 250 MB.

Below mentioned are the ways in Salesforce to call Apex class.

• From another class
• From developer console
• From JavaScript links
• From home page components
• By using trigger
• From visualforce page

Manual sharing is a process of granting access to the individual records to the user roles and public groups. This facility is available for record owners, managers, and administrators.