Handling Route Params

For our show page, we are getting the ID from the query string in the URL. This is not the best way to do this. Instead, we should be using route parameters. This will allow us to have a URL like /listings/1 instead of /listings?id=1. So yes, we are going to refactor the router again.

First, let's go to the routes.php file and change this:

$router->get('/listing', 'ListingController@show');

to this:

$router->get('/listings/{id}', 'ListingController@show');

This is in line with RESTful url standards. Now we need to update the Router class to handle this.

Open Router.php and modify the route method:

First, instead of passing the method in as a param, we are going to get it here and put it into a variable. The main reason for this is because later, we will need to manually pass in a _method input if we want to make a PUT or DELETE request. So we will need to match against that.

public function route($uri) // Remove $method param
  {
    $requestMethod = $_SERVER['REQUEST_METHOD']; // Add this

    foreach ($this->routes as $route) {
      // ...
    }
  }

After making those changes, go to the public/index.php file and remove this line:

$method = $_SERVER['REQUEST_METHOD'];

And remove the $method param from the route method call:

$router->route($uri);

The app should still work the same way.

Route Parameters

Now we need to account for the {$id} param in the route.

In the route method, we are going to add a bunch of code within the foreach. Replace everything in the foreach with the following:

foreach ($this->routes as $route) {
  // Split the URI into segments
  $uriSegments = explode('/', trim($uri, '/'));

  // Split the route URI into segments
  $routeSegments = explode('/', trim($route['uri'], '/'));

  // Check if the number of segments matches
  if (count($uriSegments) === count($routeSegments) && strtoupper($route['method']) === $requestMethod) {
    $params = [];

    // Compare each segment
    $match = true;

    for ($i = 0; $i < count($uriSegments); $i++) {
      if ($routeSegments[$i] !== $uriSegments[$i] && !preg_match('/\{(.+?)\}/', $routeSegments[$i])) {
        $match = false;
        break;
      }
      if (preg_match('/\{(.+?)\}/', $routeSegments[$i], $matches)) {
        // This segment is a parameter, so store it
        $params[$matches[1]] = $uriSegments[$i];
      }
    }

    if ($match) {
      // Extract controller and method from route
      $controller = 'App\\Controllers\\' . $route['controller'];
      $controllerMethod = $route['controllerMethod'];

      // Instantiate the controller and call the method, passing parameters
      $controllerInstance = new $controller();
      $controllerInstance->$controllerMethod($params);
      return;
    }
  }
}

Let's go over this code:

First, we are splitting the URI and the route URI into segments. The $uriSegments will be an array of each segment in the URI. So if it is /listings/1, it will be:

[
  'listings',
  '1'
]

We could get the id with $uriSegments[1].

The $routeSegments will be an array of each segment in the route URI.

You can check and see all of the values by using our inspectAll helper function:

inspectAll($uriSegments);
inspectAll($routeSegments);

We are then checking if the number of segments match and if the request method matches. So if we are hitting /listings/2 with a GET request, it will match GET /listings/{id}.

Then we initialize an empty $params array and set $match to true.

We then loop through each segment and check if they match. If they don't match and the segment is not a parameter, we set $match to false and break out of the loop. The preg_match function is checking if the segment is a parameter with curly braces. So if it is something like {id}. If it is, it will return true and store the name of the parameter in $matches[1]. If not, it will set $match to false and break out of the loop.

If it is a match, we extract the controller and method from the route. We then instantiate the controller and call the method, passing in the $params array. This is the same as we had before, except now we are passing in the $params array, which we will have access to in the controller.

Update Controller

Now, we have to update the show method in the ListingController to accept the $params array. We need to pass in the $params array and we no longer need the $_GET superglobal. Replace it with $params['id']:

public function show($params)
  {
    $id = $params['id'];

    $params = [
      'id' => $id,
    ];

    $listing = $this->db->query('SELECT * FROM listings WHERE id = :id', $params)->fetch();

     // Check if listing exists
    if (!$listing) {
      ErrorController::notFound('Listing not found');
      return;
    }

    loadView('listings/show', [
      'listing' => $listing,
    ]);
  }

Now you should see the listing when you go to /listings/1 or whatever id you want.

Update Links

Now we just need to update any links that are using the query string. So in the App/views/listings/index.view.php file and in the App/views/home.view.php, change this:

<a href="/listing?id=<?php echo $listing['id']; ?>">

to this:

<a href="/listings/<?php echo $listing['id']; ?>">

Make sure you use plural. This adheres to RESTful standards.