更新模型Laravel时出错

Question

我有一个模型文章：

class Article extends Model
{

    protected $fillable = [
        'title',
        'slug',
        'body',
        'category_id'
    ];

    public function category()
    {
        return $this->belongsTo('App\Category');
    }

}

当我去编辑表单并单击更新时，我收到此错误：

Column not found: 1054 Unknown column '_method' in 'field list' (SQL: update `articles` set `_method` = PATCH, `_token` = s9ee0UZQwqFbnjuzGv9pSMdz2xpudks715WOhbL1, `title` = 111, `slug` = 111, `category_id` = 1, `body` = 111, `updated_at` = 2015-06-01 22:51:10)

什么可能导致问题？

这是update()方法：

public function update(Article $article, ArticleRequest $request)
{
    $article->update($request->all());

    return redirect('admin/article');
}