Understand Laravel route with optional parameter

问题

I'm trying to create a route with one optional parameter with Laravel 5.4.

Route :

Route::get('/run/{zone?}/id/{id}', 'RunController@show');

Controller :

class RunController extends Controller
{
    public function show()
    {
        $route = \Route::current();
        $zone = $route->parameter('zone') ?: 'default';
        $id = $route->parameter('id');

        Run::setZone($zone);
        $run = Run::findOrFail($id);
        return view('run.show')->with(['run' => $run]);
    }
}

The url run/test/id/42 works like expected.

But with run/id/42 I got a nice NotFoundHttpException in RouteCollection.php when I expect the same result than run/default/id/42

What did I missed ?

回答1:

Everything after the first optional parameter must be optional. If part of the route after an optional parameter is required, then that parameter becomes required.

In your case, the id/{id} part of the route is non-optional, so the "optional" parameter before that section of the route becomes required.

Laravel's routing is actually built on top of Symfony's routing, and this is a restriction in Symfony. According to the Symfony documentation here (emphasis mine):

Of course, you can have more than one optional placeholder (e.g. /blog/{slug}/{page}), but everything after an optional placeholder must be optional. For example, /{page}/blog is a valid path, but page will always be required (i.e. simply /blog will not match this route).

Additionally, another thing to watch out for:

Routes with optional parameters at the end will not match on requests with a trailing slash (i.e. /blog/ will not match, /blog will match).

回答2:

Optional parameters work when it is the last URL element so in your case it won't work.

来源：https://stackoverflow.com/questions/43666683/understand-laravel-route-with-optional-parameter