Use a fallback locale when generating a url for an unregistered localized route

Author: ivanvermeyen

src/Illuminate/Routing/UrlGenerator.php

@@ -93,26 +93,29 @@ protected function resolveLocalizedRouteName($name, $locale, $currentLocale)
             return $name;
         }
 
+        // Normalize the route name by removing any locale prefix.
+        // We will prepend the applicable locale manually.
+        $baseName = $this->stripLocaleFromRouteName($name);
+
+        if ($baseName === '') {
+            return '';
+        }
+
         // Use the specified or current locale
         // as a prefix for the route name.
         $locale = $locale ?: $currentLocale;
+        $newName = "{$locale}.{$baseName}";
+        $fallbackLocale = LocaleConfig::getFallbackLocale();
 
-        // If the locale is not supported, use a fallback
-        // locale if one is configured.
-        if ( ! LocaleConfig::isSupportedLocale($locale)) {
-            $locale = LocaleConfig::getFallbackLocale() ?: $locale;
+        // If the localized route name doesn't exist,
+        // use a fallback locale if one is configured.
+        if ( ! Route::has($newName) && $fallbackLocale) {
+            $newName = "{$fallbackLocale}.{$baseName}";
         }
 
-        // Normalize the route name by removing any locale prefix.
-        // We will prepend the applicable locale manually.
-        $baseName = $this->stripLocaleFromRouteName($name);
-
-        // If the route has a name (not just the locale prefix)
-        // add the requested locale prefix.
-        $newName = $baseName ? "{$locale}.{$baseName}" : '';
-
-        // If the new localized route name does not exist, but the unprefixed route name does,
-        // someone is calling "route($name, [], true, $locale)" on a non localized route.
+        // If the unprefixed route name exists, but the new localized route name doesn't,
+        // someone may be trying to resolve a localized name in an unsupported locale,
+        // e.g. "route('en.route', [], true, 'fr')" (where 'fr.route' doesn't exist and 'route' does)
         // In that case, resolve the unprefixed route name.
         if (Route::has($baseName) && ! Route::has($newName)) {
             $newName = $baseName;

tests/Unit/Illuminate/Routing/UrlGeneratorTest.php

@@ -184,14 +184,14 @@ function it_uses_a_fallback_locale_when_the_requested_locale_is_unsupported()
     /** @test */
     public function it_uses_a_fallback_locale_when_the_requested_locale_is_not_registered()
     {
-//        $this->setSupportedLocales(['en', 'nl']);
-//        $this->setAppLocale('en');
-//        $this->setFallbackLocale('en');
-//
-//        Route::get('en/route')->name('en.route');
-//
-//        $this->assertEquals(URL::to('en/route'), URL::route('route', [], true, 'en'));
-//        $this->assertEquals(URL::to('en/route'), URL::route('route', [], true, 'nl'));
+        $this->setSupportedLocales(['en', 'nl']);
+        $this->setAppLocale('en');
+        $this->setFallbackLocale('en');
+
+        Route::get('en/route')->name('en.route');
+
+        $this->assertEquals(URL::to('en/route'), URL::route('route', [], true, 'en'));
+        $this->assertEquals(URL::to('en/route'), URL::route('route', [], true, 'nl'));
     }
 
     /** @test */