php - Laravel 5.5 编辑后无法删除类别

Question

当我编辑帖子时，我想删除已取消的类别。我使用同步方法，但它不起作用..

编辑 Blade

<select class="form-control m-select2" id="m_select2_3" name="categories[]" multiple="multiple">
  <optgroup label="Kategoriler">
     @foreach($categories as $category)
        <option value="{{$category->id}}"  {{ in_array($category->id,$categoriesPost) ? 'selected' : '' }}>{{$category->category_name}}
  </option>
     @endforeach
   </optgroup>
 </select>

和 Controller

public function update(StoreBlogPost $request, $id){

        $post = Post::find($id);

        $post->title = $request->title;
        $post->caption = $request->caption;
        $post->content = $request->input('content');

        $post->save();
        $post->categories()->sync($request->categories, false);

        return redirect()->route('posts.index');
    }

有什么建议吗？

Answer 1

您应该将sync的第二个参数设置为true。

从代码中，

/**
 * Sync the intermediate tables with a list of IDs or collection of models.
 *
 * @param  \Illuminate\Database\Eloquent\Collection|\Illuminate\Support\Collection|array  $ids
 * @param  bool   $detaching
 * @return array
 */
public function sync($ids, $detaching = true)
{
    ....
}

这意味着，$ids 中不存在的 ID 将被分离。