CodeIgniter Routing Guide | Generated by AI

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Overview of CodeIgniter Routing

CodeIgniter’s routing system allows you to map URLs (URIs) to specific controller classes and methods, overriding the default URL pattern of example.com/controller/method/id/. This is useful for creating SEO-friendly URLs, handling RESTful APIs, or simply customizing how requests are processed.

The provided code snippet is from CodeIgniter’s routes.php configuration file. It defines an associative array $route where each key is a URI pattern, and the value is either a string (controller/method) or an array specifying different behaviors by HTTP method (e.g., GET, POST). This setup supports both standard routing and method-specific routing.

I’ll break down how routes are defined, how they work, and how to use them, based on CodeIgniter’s standard behavior and the example in your code. For full details, refer to the official CodeIgniter User Guide on routing: https://codeigniter.com/userguide4/general/routing.html.

1. How to Define Routes

Routes are defined in application/config/routes.php as an array. You add entries to $route[]. Here’s the syntax:

• Basic Route: Maps any HTTP method to a controller/method.

  $route['uri_segment'] = 'controller/method';
  

  • Example: $route['login'] = 'users/login'; means any request to /login routes to Users::login().
• Method-Specific Route: For RESTful APIs, you can specify different controllers/methods per HTTP method (GET, POST, PUT, etc.). This uses an array.

  $route['uri_segment'] = array(
      'METHOD1' => 'controller/method1',
      'METHOD2' => 'controller/method2'
  );
  

  • Example from your code: $route['self'] = array('POST' => 'users/update', 'GET' => 'users/self'); means:
    • POST to /self → Users::update().
    • GET to /self → Users::self().
• Wildcard Placeholders: Use regex-like patterns to capture dynamic parts of the URL (passed as parameters to the method).
  • (:any): Matches any character (except slashes) – e.g., slugs or strings.
  • (:num) or (\d+): Matches digits only – for IDs.
  • Custom regex: Wrap in parentheses, e.g., (foo|bar) for specific matches.
  • Examples from your code:
    • $route['users/(\d+)']['GET'] = 'users/one/$1';: GET /users/123 routes to Users::one(123).
    • $route['lives/(\d+)/notify'] = 'lives/notifyLiveStart/$1';: Any method to /lives/123/notify routes to Lives::notifyLiveStart(123).
• Reserved Routes:
  • $route['default_controller'] = 'welcome';: The controller loaded if no URI is given (e.g., root URL → Welcome controller).
  • $route['404_override'] = 'errors/page_missing';: The controller/method for unmatched routes (custom 404).
  • $route['translate_uri_dashes'] = FALSE;: If TRUE, converts dashes in URIs to underscores for controller/method names (e.g., my-controller → my_controller).
• Order Matters: Routes are matched in the order they appear. Define specific routes (with wildcards) before general ones to avoid conflicts.
• HTTP Methods: If not specified, a route applies to all methods. Your code uses arrays for specificity, which is great for APIs.

Tips for Defining Routes in Your Code:

• Add new routes at the end, before $route['translate_uri_dashes'].
• Test with tools like Postman for API routes to ensure the correct controller/method is hit.
• For complex apps, group routes by section (as you’ve done with comments like // users).

2. How Routes Work

CodeIgniter’s router processes each incoming request in this order:

1. Parse the URI: Breaks down the URL into segments (e.g., /users/123/edit → segments: users, 123, edit).
2. Match Against Routes: Checks the $route array from top to bottom. It looks for exact matches first, then patterns with wildcards.
   • If a match is found, it maps to the specified controller/method, passing dynamic parts (e.g., 123) as method arguments.
   • If no match, it falls back to the default pattern (Controller::method/id/).
3. Load Controller & Method: CodeIgniter instantiates the controller, calls the method, and passes any URI segments or captured groups.
4. Method-Specific Handling: If the route is an array (like in your code), it checks the HTTP method (GET, POST, etc.) from the request.
5. Fallback: Unmatched requests trigger a 404, or the $route['404_override'] if set.

Example Flow:

• Request: POST https://example.com/lives
• Matches: $route['lives']['POST'] = 'lives/create';
• Result: Calls Lives::create() with no arguments.
• If the request was GET https://example.com/lives/456, it would match $route['lives/(\d+)']['GET'] = 'lives/one/$1'; → Lives::one(456).

Key Mechanics:

• Dynamic Parameters: Captured groups (e.g., $1) are passed as args to the method. Ensure your controller method expects them.
• Security: Routes help prevent direct access to sensitive controllers by obscuring URLs.
• Performance: Simple array lookups; no major overhead unless you have hundreds of routes.

3. How to Use Routes

Using routes means setting them up as above, then leveraging them in your application (controllers, views, etc.).

• In Controllers: Assume the route handles URL mapping; write methods expecting routed requests.
  • Example: For $route['login']['POST'] = 'users/login';, create a Users.php controller with a login() method that handles POST data (e.g., via $this->input->post()).
• Generating URLs: Use CodeIgniter’s site_url() or base_url() with your route keys for links/buttons.
  • Example: In a view, <a href="<?= site_url('login'); ?>">Login</a> points to the routed URL, but your code defines what controller it hits.
• Testing Routes:
  • Use your web browser or API tools (e.g., Postman) to hit URLs like /users/register.
  • Check application/logs/log-{date}.php for errors if routes fail.
  • Add debug: Temporarily reset $route['404_override'] and use var_dump in a test controller to see parameters.
• RESTful Usage (Like in Your Code): Your routes are set up for an API-like structure. For example:
  • Creating a resource: Send POST to /lives → Creates a live event.
  • Reading: GET /lives/123 → Fetch live event #123.
  • Updating: POST /lives/123 → Update live event #123.
• Common Pitfalls & Tips:
  • Duplicates: Avoid overlapping routes (e.g., lives and lives/(\d+)); put specifics first.
  • Methods Not Specified: If a route is a string, it works for all HTTP methods. Use arrays for precision.
  • For Development: Enable CodeIgniter’s Profiler ($this->output->enable_profiler(TRUE);) in a controller to debug routing.
  • Version Control: Your routes.php is in version control – changes affect routing live.
  • Extensions: If you need advanced features (e.g., namespace support), consider CodeIgniter 4 or third-party libraries, as CI 3 (your code) is older.

If you have specific questions about a route in your file (e.g., why (\d+) is used or how to add a new one), provide more details! For CodeIgniter setup, ensure CI_VERSION is defined in your index.php.

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