[11.x] Replace all backed enums with values when building URLs (#51524)

* Replace all enums with values when generating URLs

* Update UrlGenerator.php

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Illuminate/Routing/UrlGenerator.php

@@ -525,13 +525,17 @@ public function route($name, $parameters = [], $absolute = true)
     public function toRoute($route, $parameters, $absolute)
     {
         $parameters = collect(Arr::wrap($parameters))->map(function ($value, $key) use ($route) {
-            $value = $value instanceof UrlRoutable && $route->bindingFieldFor($key)
+            return $value instanceof UrlRoutable && $route->bindingFieldFor($key)
                     ? $value->{$route->bindingFieldFor($key)}
                     : $value;
-
-            return $value instanceof BackedEnum ? $value->value : $value;
         })->all();
 
+        array_walk_recursive($parameters, function (&$item) {
+            if ($item instanceof BackedEnum) {
+                $item = $item->value;
+            }
+        });
+
         return $this->routeUrl()->to(
             $route, $this->formatParameters($parameters), $absolute
         );

tests/Routing/RoutingUrlGeneratorTest.php

@@ -887,6 +887,22 @@ public function testRouteGenerationWithBackedEnums()
         $this->assertSame('http://www.foo.com/foo/fruits', $url->route('foo.bar', CategoryBackedEnum::Fruits));
     }
 
+    public function testRouteGenerationWithNestedBackedEnums()
+    {
+        $url = new UrlGenerator(
+            $routes = new RouteCollection,
+            Request::create('http://www.foo.com/')
+        );
+
+        $namedRoute = new Route(['GET'], '/foo', ['as' => 'foo']);
+        $routes->add($namedRoute);
+
+        $this->assertSame(
+            'http://www.foo.com/foo?filter%5B0%5D=people&filter%5B1%5D=fruits',
+            $url->route('foo', ['filter' => [CategoryBackedEnum::People, CategoryBackedEnum::Fruits]]),
+        );
+    }
+
     public function testSignedUrlWithKeyResolver()
     {
         $url = new UrlGenerator(