How to check for absolute paths/routes in Symfony?

Question

First of all thank you for taking your time takling this difficult topic.

Goal:

My URL structure is like facebook/twitter: site.com/Username

To let the user set the username, I need to check if a path of a route matches a username.

Possibilities & problems:

If somebody is interested, the possible solutions I came up with:

1.) Using getRouteCollection()

Problem: This method shouldn't be used because it rebuilds the route cache and kills performance (see https://github.com/symfony/symfony-docs/issues/6710)

2.) Using a blacklist as RegExp in the User (for Username) Entity to blacklist all sites like "settings", "about", "login", "register"...

* @Assert\Regex(pattern="/^(?!register)(?!login)...

Problem: This is nearly guaranteed to explode because sometimes a URL is forgotten to add into this RegExp

3.) Using CURL to check if the site.com/username results in a 404

Problem: This seems to be a "hack" for me and unprofessional.

Question:

Whats the professional, secure way of checking if a route doesn't already exists, so that the username can be set and is guaranteed to be "free" (via absolute path like site.com/Username and no other route is in the way)?

By example something like $app->hasURL('/username')

I thinking you are over thinking the problem. Routes are matched in the order they are defined so as long as you define /register,/login etc before /{username} then all will be well. — Cerad, Aug 24 '17 at 22:28

score 2 · Accepted Answer · answered Aug 24 '17 at 22:13

Add: use \Symfony\Component\RoutingException\ResourceNotFoundException;

Then, where $router is the routing service, you can attempt to match the url to a route. If it doesn't match anything it will throw an exception, but if you have a default catch-all route it will always match something so you would need to just detect if it matches the catch-all instead:

$routeIsAvailable = false;

try {
    $route = $router->match( '/' . $username );

    // If you are using a catch-all route to load profiles
    if ( $route[ '_route' ] === 'name_of_catch_all_route' )
        $routeIsAvailable = true;

} catch ( ResourceNotFoundException ) {

    // If the url didn't match any route at all
    $routeIsAvailable = true;
}

Make sure that you validate $username first so that it doesn't have any characters like ? or /. You can also urlencode it, but you probably don't want your user's profile urls to have encoded characters in them, so it's better to just restrict the valid usernames.

How to check for absolute paths/routes in Symfony?

1 Answers1