localization FakerFactory does not work in laravel

I have a Post Model with these fields :

post_id
post_title
post_content
post_content_full
author

Now I want to use laravel sedders and model factories to create fake fa_IR localized data and insert to posts table.

For that I wrote this in database/factories/ModelFactory.php:

$factory->define(AppPost::class, function (FakerGenerator $faker) {
        return [
            'post_title'        => $faker->sentence,
            'post_content'      => $faker->paragraph,
            'post_content_full' => $faker->paragraph(3),
            'author'            => $faker->name
        ];
    });

Then I created a PostsTableSeeder class like this :

use IlluminateDatabaseSeeder;

class PostsTableSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run ()
    {
        factory(AppPost::class, 5)->create();
    }
}

And in AppServiceProvider.php added below codes to register function :

$this->app->singleton(FakerGenerator::class, function () {
        return FakerFactory::create('fa_IR');
    });

But After running the seed , laravel uses default locale (en_US) and ignores fa_IR.

I do not know what else to do.

Update:

Even I changed in DEFAULT_LOCALE const vendor/fzaninotto/faker/src/Faker/Factory.php to fa_IR Nothing changed.

Answer

Not all faker methods are supported in every language, from what a quick lookup of the documentation says, the Company and Address provider are supported in the fa_IR localization