Replace matches from one string in another string - php

Question

I'm writing a router for my PHP MVC application, and I currently need to find a way to use matches in a route as variables for controllers and actions.
For example, if I have the following route: /users/qub1/home
I would like to use a regex similar to this: \/users\/(?!/).*\/(?!/).*
Then I would like to specify the action like this: $2 (in the example, this would be home)
And the parameter to pass to the action like this: $1 (in the example, this would be qub1).
This would then execute code similar to this:
$controller = new UsersController();
$controller->$2($1);
Configured routes are stored as such:
public function setRoute($route, $regex = false, $controller = 'Index', $action = 'index', $parameters = array()) {
if(!$regex) {
$route = preg_quote($route, '/');
}
$this->routes[] = [
'route' => $route,
'controller' => $controller,
'action' => $action,
'parameters' => $parameters
];
}
Where the above example would be stored like this: $router->setRoute('\/users\/(?!/).*\/(?!/).*', true, 'User', '$2', [$1]);
So essentially, I want to use matched groups from one regex expression as variables to replace inside another regex expression (if that makes sense).
I hope I've described my problem accurately enough. Thanks for the help.
EDIT:
The code I'm currently using to parse routes (it doesn't work, but it should illustrate what I'm trying to achieve):
public function executeRoute($route) {
// Loop over available routes
foreach($this->routes as $currentRoute) {
// Check if the current route matches the provided route
if(preg_match('/^' . $currentRoute['route'] . '$/', '/' . $route, $matches)) {
// If it matches, perform the current route's action
// Define names
$controllerClass = preg_replace('\$.*\d', $matches[str_replace('$', '', '$1')], ucfirst($currentRoute['controller'] . 'Controller'));
$actionMethod = preg_replace('\$.*\d', $matches[str_replace('$', '', '$1')], strtolower($currentRoute['action']) . 'Action');
$parameters = preg_replace('\$.*\d', $matches[str_replace('$', '', '$1')], join(', ', $currentRoute['parameters']));
// Create the controller
$controller = new $controllerClass();
$controller->$actionMethod($parameters);
// Return
return;
}
}
}

Answer 1

While I am not sure that it is a very well designed approach, it is doable. This is the code that replaces yours within the if:
// you already specify the controller name, so no need for replacing
$controllerClass = ucfirst($currentRoute['controller'] . 'Controller');
// also here, no need to replace. You just need to get the right element from the array
$actionMethod = strtolower($matches[ltrim($currentRoute['action'], '$')] . 'Action';
// here I make the assumption that this parameter is an array. You might want to add a check here
$parameters = array();
foreach ($currentRoute['parameters'] as $parameter) {
$parameters[] = $matches[ltrim($parameter, '$')];
}
// check before instantiating
if (!class_exists($controllerClass)) {
die('invalid controller');
}
$controller = new $controllerClass();
// also check before invoking the method
if (!method_exists($controller, $actionMethod)) {
die('invalid method');
}
// this PHP function allows to call the function with a variable number of parameters
call_user_func_array(array($controller, $actionMethod), $parameters);
One reason why your approach is not very favorable is that you make a lot of assumptions:
the regex needs to have as many groups as you use in the other parameters
if you are imprecise with the regex, it might be possible to call any method in your code
Maybe this will be good enough for your project but you should consider using a well-established router if you want to create something not for educational purposes.