/**
  * Show the form for editing the specified resource.
  *
  * @param  int  $id
  * @return Response
  */
 public function edit($id)
 {
     $article = \Article::find($id);
     if (!$article) {
         return Msgbox::error('文档不存在');
     }
     //读取分类
     $categories = \Category::selectOptions();
     //读取tags
     $tags = $article->getTags();
     $values = array('article' => $article, 'categories' => $categories, 'tags' => $tags);
     return View::make('admin/article/edit', $values);
 }