4. Adding Functionality with Libraries

What are CodeIgniter libraries?

In computer science, a library is a collection of functionality that serves a specific purpose with a well defined interface and logical structure. CodeIgniter comes with several dozen libraries for common tasks. Each implemented as a class. Examples of classes include the input class, form validation class and HTML table class. To use a library, it needs to be initialized within a controller using the following initialization method: this -> load ->library, followed by a string containing the machine name of the library.

For example, form_validation. Multiple libraries can be initialized at once by passing an array of strings containing the names of the libraries to load. Such as form validation and table. Each library has a dedicated page within the CodeIgniter User Guide, which includes usage examples and a function reference. In this chapter, I'm going to allow users to add magazines using a form, then validate those forms including some custom validation. After that, I'll use a number of CodeIgniter libraries to accept user input and list magazines in a generated HTML table.

Let's get started.