CodeIgniter Technology Intelligence

What is CodeIgniter?

CodeIgniter is a lightweight PHP framework known for its small footprint and exceptional performance. Originally developed by EllisLab in 2006, it's now maintained by the British Columbia Institute of Technology. CodeIgniter follows the Model-View-Controller (MVC) pattern and is designed for developers who need a simple, elegant toolkit.

With a core system of approximately 2MB, CodeIgniter is one of the fastest PHP frameworks available. It requires minimal configuration, has nearly zero mandatory dependencies, and doesn't force strict coding patterns—making it ideal for developers who want flexibility.

CodeIgniter 4, released in 2020, modernized the framework with namespaces, PSR-4 autoloading, and PHP 7+ requirements while maintaining its signature simplicity. It's particularly popular for rapid application development, REST APIs, and projects where performance is critical.

CodeIgniter Features

MVC Architecture: Clean separation. Controller routing. View templates. Model layer. Flexible structure.

Query Builder: Database abstraction. Active Record pattern. Multiple database support. Query caching. Transaction handling.

Security: XSS filtering. CSRF protection. Password hashing. Input validation. SQL injection prevention.

Libraries: Form validation. Session management. File uploading. Image manipulation. Email sending.

Helpers: URL helper. Form helper. Text helper. Array helper. Custom helper creation.

RESTful Support: Resource controllers. API responses. Content negotiation. Rate limiting. Authentication.

CodeIgniter Use Cases

Web Applications: Business applications. CRM systems. Inventory management. Project management tools.

REST APIs: Mobile app backends. Microservices. Third-party integrations. Data services.

E-commerce: Online stores. Shopping carts. Payment integration. Order management.

Content Sites: Blogs, news sites. Content management. Portfolio sites. Corporate websites.

Rapid Prototyping: MVP development. Proof of concepts. Client demos. Quick iterations.

Legacy Modernization: PHP upgrade paths. Incremental refactoring. System migrations.

CodeIgniter Code Examples

Controller Example

<?php
namespace App\Controllers;

class Users extends BaseController
{
    protected $userModel;

    public function __construct()
    {
        $this->userModel = model('UserModel');
    }

    public function index()
    {
        $data['users'] = $this->userModel->findAll();
        return view('users/index', $data);
    }

    public function create()
    {
        $validation = \Config\Services::validation();

        if ($this->request->getMethod() === 'post') {
            if ($validation->run($this->request->getPost(), 'user')) {
                $this->userModel->save($this->request->getPost());
                return redirect()->to('/users');
            }
        }

        return view('users/create', ['validation' => $validation]);
    }
}

Model Example

<?php
namespace App\Models;

use CodeIgniter\Model;

class UserModel extends Model
{
    protected $table = 'users';
    protected $primaryKey = 'id';
    protected $allowedFields = ['name', 'email', 'password'];
    protected $useTimestamps = true;

    protected $validationRules = [
        'email' => 'required|valid_email|is_unique[users.email]',
        'name'  => 'required|min_length[3]'
    ];
}

CodeIgniter Benefits

Performance: Fastest PHP framework. Minimal overhead. Small footprint. Efficient execution.

Simplicity: Gentle learning curve. Clear documentation. Minimal configuration. Logical structure.

Flexibility: Not opinionated. Use what you need. Easy customization. No forced patterns.

Lightweight: ~2MB core. Few dependencies. Quick installation. Low resource usage.

Documentation: Comprehensive user guide. Code examples. API reference. Community tutorials.

Stability: Mature framework. Production proven. Long-term support. Backward compatibility.