PHP / PHP Frameworks and CMS
Building Applications with CodeIgniter
This tutorial will teach you how to build web applications with CodeIgniter. We will cover installation, MVC architecture, creating controllers, and views.
Section overview
5 resourcesIntroduces popular PHP frameworks and content management systems.
Building Applications with CodeIgniter
1. Introduction
Goal
This tutorial aims to guide you through the process of building a simple web application using CodeIgniter, a powerful PHP framework with a very small footprint.
Learning Outcome
By the end of this tutorial, you should be able to understand and implement the MVC (Model-View-Controller) architecture, create controllers, views, and build applications with CodeIgniter.
Prerequisites
Before you start, you should have a basic understanding of PHP and MySQL. Familiarity with OOP (Object Oriented Programming) concepts would be beneficial but is not mandatory.
2. Step-by-Step Guide
Installation of CodeIgniter
To start off, download the latest version of CodeIgniter from the official website and extract it into your localhost directory.
MVC Architecture
CodeIgniter uses the MVC (Model-View-Controller) architecture.
- Model: The part of your application that handles data and database interactions.
- View: The part of your application that generates the HTML and presents data to the user.
- Controller: The part of your application that handles user interaction, works with the model, and ultimately selects a view to render.
Creating Controllers
In CodeIgniter, the first step is to create a controller. A controller is simply a class that helps delegate work. It is the stick that stirs the drink.
//Filename: application/controllers/Hello.php
<?php
class Hello extends CI_Controller {
public function index() {
echo "Hello, World!";
}
}
The above controller (Hello.php) has a function index(). When this controller is called from a URL, the index() function is executed by default.
Creating Views
A View is simply a web page, or a page fragment, like a header, footer, sidebar, etc. In other words, views are the pages that the user sees and interacts with.
//Filename: application/views/hello_view.php
<html>
<head>
<title>My Simple CodeIgniter App</title>
</head>
<body>
<h2>Hello, World!</h2>
</body>
</html>
This is a simple view that will display "Hello, World!" when called.
3. Code Examples
Example 1: Loading a View in the Controller
To load a view, we use the $this->load->view() function in our controller.
//Filename: application/controllers/Hello.php
<?php
class Hello extends CI_Controller {
public function index() {
$this->load->view('hello_view');
}
}
When the index() function of the Hello controller is called, it will load hello_view.php.
Example 2: Passing Data to the View
We can pass data to the view by sending an array or an object to the second argument of the $this->load->view() function.
//Filename: application/controllers/Hello.php
<?php
class Hello extends CI_Controller {
public function index() {
$data['message'] = 'Hello, World!';
$this->load->view('hello_view', $data);
}
}
In the view, we can display this data like so:
//Filename: application/views/hello_view.php
<html>
<head>
<title>My Simple CodeIgniter App</title>
</head>
<body>
<h2><?php echo $message; ?></h2>
</body>
</html>
This will display "Hello, World!".
4. Summary
In this tutorial, we have covered the basics of CodeIgniter including its installation, understanding MVC architecture, creating controllers, and views. The next steps would be to learn about Models and how to interact with a database using CodeIgniter's built-in classes.
5. Practice Exercises
- Exercise 1: Create a controller named
Welcomethat loads a view namedwelcome_message. - Exercise 2: Modify the
Welcomecontroller to pass a custom welcome message to thewelcome_messageview. Display this message in the view. - Exercise 3: Create a new controller that loads two different views to create a complete HTML page (for example, a
headerview and abodyview).
Remember, practice is key to mastering any programming language or framework. Happy coding!
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