Laravel Route /{username} in form action

I'm currently dealing with Image Upload in Laravel-5.3. My "profile page" routes are defined as:

/* GET request to show the profile page */

Route::get('/{username}', [
    'uses' => '\App\Http\Controllers\ProfileController@getProfile',
    'as'   => 'profile.index',

]);

/* POST request to update the Avatar (display pic) */

Route::post('/{username}', [
    'uses' => '\App\Http\Controllers\ProfileController@updateAvatar',
    'as'   => 'profile.index',
]);

Thus, the profile URL pretty much looks like example.com/john (let "john" be the username)

In the form though, I have to define the "action".

<form enctype="multipart/form-data" action="" method="POST">

How can I define the route in the form action so that the users are redirected to their own respective routes; something like " example.com/john ".

I guess I can't directly define <form action="/{username}"> as I'll be taken to http://ift.tt/2f1G9QU} instead.

via Chebli Mohamed