Question

我与事物有联系。连接上下。我想保留状态的历史记录并了解连接的当前状态。我有一个连接模型。 Connection有许多ConnectionStatus。首先，我想在Connection上创建一个属性，该属性是当前状态，它也限制ConnectionStatus中的列。到目前为止我已经这样做了：

    public function insertImages($pic_files,$pic_numbers,$sg_id){
         $check_insert_number = 0 ;
         $upload_path = '../uploads/sg/';
          $upload_path_fake = 'uploads/sg/';
          $server_ip = gethostbyname(gethostname());
          $upload_url = 'http://'.$server_ip.'/keepwords/'.$upload_path_fake;

            foreach($pic_files as $key => $value) {

            $fileinfo = pathinfo($value['name']);
            $extension = $fileinfo['extension'];
            $image_name_temp = pathinfo($value['name'], PATHINFO_FILENAME);
            $image_name = time()."_".$image_name_temp;

            $file_url = $upload_url . $image_name . '.' . $extension;
            $file_path = $upload_path . $image_name . '.'. $extension;


             try{

                move_uploaded_file($value['tmp_name'],$file_path);
                $source = imagecreatefrompng($file_path);
                $rotate = imagerotate($source, 90, 0);
                imagepng($rotate,$file_path);

           $stmt=$this->conn->prepare("INSERT INTO sg_image(url,sg_id) values (?,?)");
          $stmt->bind_param("si",$file_url,$sg_id);
          $result=$stmt->execute();
              if($result){


             $check_insert_number++;
             } else {


             }

           }catch(Exception $e){
          die($e->getMessage());

                }           

         }
         if($check_insert_number==$pic_numbers) {
             return 1 ;

         }else {
             return 0 ;

         }   
}

我不知道如何通过current_status完成排序。以下是一些有助于解释的理想用法

class Connection < ApplicationRecord
  has_many :connection_statuses, -> { order(created_at: :desc) }

  def current_status
    status = connection_statuses.first
    status.nil? ? 'unknown' : status.description
  end
end

这是一个我不理解的一般概念。感谢您的帮助！

Answer 1

自current_status以来，您无法执行您所描述的内容，因为您已定义它是模型方法，而不是表属性，因此不能在ActiveRecord关系中使用它。但是你可以将has_many关系别名化为仅限第一条记录的限制。

你可以这样做......

class Connection < ApplicationRecord
  has_many :connection_statuses, -> { order(created_at: :desc) }
  has_many :current_connections, -> { order(created_at: :desc}.limit(1) }, class_name: 'ConnectionStatus'

让你做...

disconnected_items = Connection.join(:current_connections).where("connection_statuses.description = 'disconnected'")

通过has_many关系按ActiveRecord模型属性排序

1 个答案: