public function run()
 {
     $faker = Faker::create();
     $tag_ids = Tag::lists('id');
     $article_ids = Article::lists('id');
     foreach (range(1, 30) as $index) {
         DB::table('article_tag')->insert(['article_id' => $faker->randomElement($article_ids->toArray()), 'tag_id' => $faker->randomElement($tag_ids->toArray())]);
     }
 }
 public function listForArr()
 {
     return $this->model->lists('title', 'article_id')->toArray();
 }