CakePHP 2.x：如何在控制器中获取最后一个插入单个字段？

Question

我有一个tansaction表，并有一个名为balance的字段。在这里，我尝试使用新数据更新此字段，但在新事务中插入。所以我需要控制器中的平衡场。所以，我试过下面的代码。

$client_id = $this->request->data['Transaction']['user_id'];
$new = $this->Transaction->find('first', array(
    'conditions'=>array('Transaction.user_id'=> $client_id),
    'fields'=>array('Transaction.balance')
));

$this->request->data['Transaction']['balance'] =$this->request->data['Transaction']['debit_money']-$this->request->data['Transaction']['credit_money']+new;

但在这里，我没有得到旧的余额数据。

Answer 1

$new是一个关联数组。您正在为数字添加数组。

尝试以下方法：

$client_id = $this->request->data['Transaction']['user_id'];
$new = $this->Transaction->find('first', array(
    'conditions'=>array('Transaction.user_id'=> $client_id),
    'fields'=>array('Transaction.balance')
));

$this->request->data['Transaction']['balance'] = 
    $this->request->data['Transaction']['debit_money']
    - $this->request->data['Transaction']['credit_money']
    + $new['Transaction']['balance'];

或者，这也应该有效：

$client_id = $this->request->data['Transaction']['user_id'];

$this->request->data['Transaction']['balance'] = 
    $this->request->data['Transaction']['debit_money']
    - $this->request->data['Transaction']['credit_money']
    + $this->Transaction->field('balance',array('Transaction.user_id'=> $client_id),        
));