Cakephp如何基于另一个虚拟字段创建虚拟字段

Question

我有

Contact Table : id, first_name, last_name, company_id
Company Table : id, name

我想在Contact Table中创建虚拟字段,因此它将显示为"contactInCompany"

"first_name last_name - Company.name" e.g: Andre Robin - Google

我怎么能实现这一点,我尝试这种方式,但它不起作用,它不接受另一个虚拟字段作为输入

public $virtualFields = array(
    'companyName' => 'SELECT name FROM companies where id = Contact.company_id',
    'customerWithCompany' => "CONCAT(Contact.first_name, ' ', 
                              Contact.last_name, ' ', Contact.companyName, '')"     
    );

我也用这种方式尝试过它并不起作用

'customerWithCompany' => "CONCAT(Contact.first_name, ' ', Contact.last_name, '-', 
                         SELECT name FROM companies where id = Contact.company_id)"

我经常需要这个,我会使用它来放入下拉选择框以选择联系人,所以我希望将联系人名称与公司一起显示

Answer 1

您无法使用虚拟字段执行此操作,因为虚拟字段中的键只是别名

例:

class Contact extends AppModel {

  public $virtualFields = array(
      'companyName' => 'SELECT name FROM companies where id = Contact.company_id',
      'customerWithCompany' => "CONCAT(Contact.first_name, ' ', 
                                 Contact.last_name, ' ', Contact.companyName, '')"     
       );

    public function getContacts() {
      return $this->find('all', array(
                   'fields'=>array(
                            'Contact.id',
                            'Contact.first_name', 
                            'Contact.companyName', 
                            'Contact.customerWithCompany'
                           )
                    )
               );
    }

}

如果从ContactsController调用getContacts()方法

上面的代码将形成此查询:

SELECT Contact.id, Contact.first_name, 
       (SELECT name FROM companies where id = Contact.company_id) AS Contact__companyName, 
       CONCAT(Contact.first_name, ' ', Contact.last_name, ' ', Contact.companyName, '') AS Contact__customerWithCompany
FROM contacts AS Contact;

此查询将不会在mysql上执行,因为无法访问另一列的1列别名.

要实现这一点,你必须使用如下的子查询:Cake php将虚拟字段名称转换为Model__(在下面的例子中是Contact__)

SELECT 
SubQuery.id, 
SubQuery.first_name, 
SubQuery.Contact____companyName,
CONCAT(SubQuery.first_name, ' ', SubQuery.last_name, ' ', SubQuery.Contact____companyName, '') AS Contact__customerWithCompany 

FROM 
(SELECT Contact.id, Contact.first_name, (SELECT name FROM companies where id = Contact.company_id) AS Contact__companyName
FROM contacts AS Contact) AS SubQuery;

如果你想在cake php中构建子查询,请使用DataSource的buildStatement方法

注意:使用联接是上述查询的另一个更好的解决方案,可以在不使用子查询的情况下实现相同的结果

加入:

public function getContacts() {
    $this->virtualFields['customerWithCompany'] = "CONCAT(Contact.first_name, ' ', Contact.last_name, ' ', Company.name)";
    return $this->find('all', array(
            'fields'=>array(
                'Contact.id',
                'Contact.first_name',
                'Contact.last_name',
                'Company.name',
                'Contact.customerWithCompany'
            ),
            'joins'=>array(
                array(
                    'table'=>'companies',
                    'alias'=>'Company',
                    'type'=>'LEFT',
                    'conditions'=>array(
                        'Contact.company_id = Company.id'
                    )
                )
            )
        )
    );
}