在CakePHP中创建虚拟字段 [英] creating virtual fields on the fly in CakePHP

问题描述

我希望即时创建虚拟字段。

I wish to create virtual fields on the fly.

我的订单&订单详情就像...

My Order & Order Details are like...

//Order Model
class Order extends AppModel {
    public $name = 'Order';
    public $actsAs = array('Containable');
    public $hasMany = array(
        'OrderDetail' => array(
            'className' => 'OrderDetail',
            'foreignKey' => 'order_id',
            'dependent' => true
        ),
    );
}

//OrderDetail Model
  class OrderDetail extends AppModel {
    public $name = 'OrderDetail';
    public $actsAs = array('Containable');
    public $belongsTo = array(
        'Order' => array(
            'className' => 'Order',
            'foreignKey' => 'order_id',
            'dependent' => true
        ),
    );
}

模型关系如下。我正在创建虚拟字段，以便我可以计数项目和他们的成本，以分页。我知道 requestAction 的奇怪的方式。

The model relation is like this. I am creating virtual fields on the fly so that I can count number of items and their cost in order pagination. I know the weird way of requestAction. Is their any way other I can perform my task.

我尝试的代码是

        $this->Order->virtualFields['totalCost'] = 0;
        $this->Order->virtualFields['totalItem'] = 0;
        $fields = array('Order.id', 'Order.order_key', 'Order.delivery_date','COUNT(`OrderDetail`.`order_id`) AS `Order__totalItem`', 'SUM(`OrderDetail`.`cost`) AS `Order__totalCost`');         

        $this->paginate['Order'] = array("fields"=>$fields, 'conditions' => array("AND" => array($condition, "Order.status" => 3)), 'limit' => '50', 'order' => array('Order.id' => 'DESC'));

它结束我与mysql未找到列未知列'OrderDetail.order_id 'in'field list'。我没有放弃递归或绑定我的模型，以找到别的东西。为什么会生成此错误？如何实现我的目标。

It ends me with the mysql not found column Unknown column 'OrderDetail.order_id' in 'field list'. I haven't put recursive or bind my model to find something else. Why this error is generated ? How can I achieve my aim.

推荐答案

您可以即时创建虚拟字段。您的语法是正确的，但您也可以这样做：

you can create virtual fields on the fly. Your syntax is correct but you can do also this way:

$this->Order->virtualFields['totalCost'] = 'SUM(`OrderDetail`.`cost`)';
$this->Order->virtualFields['totalItem'] = 'COUNT(`OrderDetail`.`order_id`)';

这里的问题是Order与OrderDetail有HasMany关系。 CakePHP在这种情况下不加入表，而是进行两个查询，一个用于订单，一个用于OrderDetail，然后合并记录集。

the problem here is that Order is in HasMany relationship with OrderDetail. CakePHP in this case doesn't join the tables but rather makes two queries, one for the Orders and one for the OrderDetail and then merge the recordsets.

你能做什么？

您可以分页OrderDetail而不是Order，然后按Order.id

you can paginate OrderDetail instead of Order, and group it by Order.id

$fields = array
(
    'Order.id', 
    'Order.order_key', 
    'Order.delivery_date', 
    'Order.totalItem', 
    'Order.totalCost'
);         

$this->paginate['OrderDetail'] = array
(
    "fields"=> $fields, 
    'conditions' => array("AND" => array($condition, "Order.status" => 3)), 
    'limit' => '50', 
    'order' => array('Order.id' => 'DESC'),
    'group' => array('Order.id')
);

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