用变量调用PHP类变量 - Calling a PHP class variable with a variable

Calling a PHP class variable with a variable

本文关键字：类变量 PHP 调用变量 | 更新日期: 2023-09-27

我有一个PHP类定义，它为所有典型的数据库方法(Crud等)使用一个名为databaseObject的类。我最近更改了数据库结构，使每个表中的id列不再称为"id"，而现在是表中包含的+ id(例如:Companies table的id为"companyId")。现在，在扩展databaseObject的类中，我包含了一个名为$table_id的静态变量，它保存了该表的id名。我遇到了一种情况，现在我需要调用这个类变量。下面是示例代码。这段代码在PHP 5.3中运行。

//databaseObject Delete Method;
public function delete() {
    global $database;
    //DELETE FROM table WHERE condition LIMIT 1
    //escape all values to prevent SQL injection
    // - use LIMIT 1
    $sql  = "DELETE FROM ".static::$table_name;
    $sql .= " WHERE ".static::$table_id."=". $database->escape_value($this->id);
    $sql .= " LIMIT 1"; 
    $database->query($sql);
    return ($database->affected_rows() ==1) ? true : false;
}
//Actual Class that creates the issue
require_once(LIB_PATH.DS.'database.php');
require_once(LIB_PATH.DS.'databaseobject.php');
class Contact extends DatabaseObject {
    protected static $table_name="contacts";
    protected static $table_id="contactId";
    protected static $db_fields = array('contactId','companyId','contactName', 'phone', 'fax', 'email');
    public $contactId;
    public $companyId;
    public $contactName;
    public $phone;
    public $fax;
    public $email;
}
//Code that calls the method
$contact = Contact::find_by_id($_GET['contactId']);
if($contact && $contact->delete()) {
    $session->message("The Contact was deleted.");
    log_action('Contact Deleted', "Contact was deleted by User ID {$session->id}");
    redirect_to("../companies/viewCompany.php?companyId={$contact->companyId}");    
} else {
    $session->message("The Contact could not be deleted");
    redirect_to('../companies/listCompanies.php');

}

使用self::$variable而不是static::$variable

你需要的是反射

class Foo {
    protected $bar = 'barrr!';
    private $baz = 'bazzz!';
}
$reflFoo = new ReflectionClass('Foo');
$reflBar = $reflFoo->getProperty('bar');
$reflBaz = $reflFoo->getProperty('baz');
// Set private and protected members accessible for getValue/setValue
$reflBar->setAccessible(true);
$reflBaz->setAccessible(true);
$foo = new Foo();
echo $reflBar->getValue($foo); // will output "barrr!"
echo $reflBaz->getValue($foo); // will output "bazzz!"
// You can also setValue
$reflBar->setValue($foo, "new value");
echo $reflBar->getValue($foo); // will output "new value"

通过Contract::$table_id访问字段名，得到值contractId。所以，如果我理解正确的话，您想要得到$contract->contractId，但是名称contractId是由在此之前执行的代码决定的。