Flarum\Util\Str::slug PHP Method

    public static function slug($str)
    {
        $str = strtolower($str);
        $str = preg_replace('/[^a-z0-9]/i', '-', $str);
        $str = preg_replace('/-+/', '-', $str);
        $str = preg_replace('/-$|^-/', '', $str);
        return $str ?: '-';
    }

 public function up()
 {
     $this->schema->table('discussions', function (Blueprint $table) {
         $table->string('slug');
     });
     // Store slugs for existing discussions
     $this->schema->getConnection()->table('discussions')->chunk(100, function ($discussions) {
         foreach ($discussions as $discussion) {
             $this->schema->getConnection()->table('discussions')->where('id', $discussion->id)->update(['slug' => Str::slug($discussion->title)]);
         }
     });
 }