guarded instead of fillable

database/factories/CityFactory.php

@@ -26,6 +26,7 @@ class CityFactory extends Factory
         return [
             'country_id' => Country::factory(),
             'name' => $this->faker->name,
+            'slug' => $this->faker->slug,
         ];
     }
 }

database/migrations/2022_12_01_145949_create_cities_table.php

@@ -19,6 +19,7 @@ class CreateCitiesTable extends Migration
             $table->id();
             $table->foreignId('country_id')->constrained()->cascadeOnDelete()->cascadeOnUpdate();
             $table->string('name');
+            $table->string('slug')->unique();
             $table->timestamps();
         });
 

database/seeders/DatabaseSeeder.php

@@ -59,14 +59,17 @@ class DatabaseSeeder extends Seeder
         City::create([
             'country_id' => 1,
             'name'       => 'Füssen',
+            'slug'       => str('Füssen')->slug('-', 'de'),
         ]);
         City::create([
             'country_id' => 2,
             'name'       => 'Wien',
+            'slug'       => str('Wien')->slug('-', 'de'),
         ]);
         City::create([
             'country_id' => 3,
             'name'       => 'Zürich',
+            'slug'       => str('Zürich')->slug('-', 'de'),
         ]);
         Venue::create([
             'city_id' => 1,