CodeIgniter Libraries

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A CodeIgniter library is a PHP class. The scope of the library can be any project resource, such as helpers, models, controllers, and views.
The CodeIgniter libraries are powering efficiency, code reusability, separation, and simplicity.

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In CodeIgniter, we have two types of libraries:
Built-in libraries: These are stored in the system/libraries directory.
Custom libraries: These are created in the application/libraries directory.
To reuse the code, the libraries can be loaded by any project controller, model, or helper anywhere in the Codeigniter project.
The use of libraries makes the project easy to understand and maintain.

Loading a library:

We can load a library by two methods:

1 Automatically loading: We can load a library automatically by adding a given line in the application/cofig/autoload.php file.

$autoload['libraries'] = array('database','my_lib');

Here, my_lib is the library that we want to load automatically for the entire project.

2 Manually loading: We can add a library in a certain controller, model, or method by the following line.

$this->load->library('my_lib');

Here, my_lib is the name of the library that we want to load.

To load more than one library, we use a multiple array that contains all libraries.

$this->load->library(array(' form_validation ', ' pagination '));

Creating a library:

These libraries are stored in the application/libraries folder. There are three methods to create a custom library.

Creating a new library
Extending a native library
Replacing a native library

1 Creating a new library:

To create a new library, open the application/libraries directory.
The first letter of the file name must be in uppercase.
The first letter of the library class name must be in uppercase.
The file name and class name must be the same for better convenience.

Syntax:

$this->load->library('Custom_library.php')

Here, Custom_library.php is the name of the library file created in the application/libraries directory.

Note:

we can also use custom_ library.php instead of Custom_library.php in the above line.

To access this library, use the following line.

$this-> custom_ library ->lib_method();

Here, lib_method is a function of library custom_ library.

2 Extending a native library:

Codeigniter provides the facility that you can add one or more methods in the old library to extend the functionality of it. There are some rules which should be followed:
The New class extends the native library class.
Every new class start with the prefix MY_.

For example: To extend the CodeIgniter table library. Open application/ libraries directory. Create a file MY_Table.php and create a class in it which extends the CI_Table class as:

Class MY_ Table extends CI_ Table {
	…………
	}

3 Replacing a native library: CodeIgniter provides the facility that you can override a native library.

To replace a native library, create a new file with the same name in the application/ libraries directory.

For example: To replace the table library, create a file Table.php in the application/ libraries directory. In this file create class CI_Table.