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PDO::setAttribute,如何在将PDO :: ATTR_DEFAULT_FETCH_MODE设置为PDO :: FETCH_CLASS时提供类名.
这是我正在使用的代码..我想设置它所以我的所有行都作为DB_Row的实例返回：
class DB_Row extends ArrayObject {}
$db = new PDO('MysqL:dbname=example;host=localhost','user','pass');
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE,PDO::FETCH_CLASS);
$stmt = $db->query("SELECT * FROM `table` WHERE `id` = 1;");
$row = $stmt->fetch(); // I want a DB_Row by default!
上面的代码导致PDOException,因为未分配DB_Row类名.
Fatal error: Uncaught exception 'PDOException' with message 'sqlSTATE[HY000]: General error: No fetch class specified
我该怎么做？
提前致谢..
解决方案：我使用了fireeyedboy的答案.它对我的情况起了最好的作用,因为我已经将PDOStatement扩展用于记录目的……
class DB extends PDO {
public function __construct($host = null,$user = null,$pass = null,$db = null) {
try {
parent::__construct('MysqL:dbname=' . $name .';host=' . $host,$user,$pass);
$this->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
$this->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE,PDO::FETCH_CLASS);
$this->setAttribute(PDO::ATTR_STATEMENT_CLASS,array('DB_Query',array('DB_Row')));
} catch (PDOException $e) {
die('Database Error');
}
}
}
class DB_Query extends PDOStatement {
private $class;
protected function __construct ($class = 'DB_Row') {
$this->class = $class;
$this->setFetchMode(PDO::FETCH_CLASS,$this->class);
}
}
class DB_Row extends ArrayObject {
public function __set($name,$val) {
$this[$name] = $val;
}
public function __get($name) {
return $this[$name];
}
}
另一种破解方法是扩展PDOStatement,覆盖其获取方法,并让您的PDO实例将其用作默认语句类.
作为一个例子,我只是演示覆盖fetch()1并留下fetchAll()以及你有什么打算,如果你想走这条路：
class Db_Row
{
}
class PDOStatementWithClass
extends PDOStatement
{
private $fetch_class;
// PHP complained when I tried to make this public
protected function __construct( $fetch_class = 'StdClass' )
{
// internally set the fetch class for later use
$this->fetch_class = $fetch_class;
}
// let $fetch_style default to PDO::FETCH_CLASS in stead of PDO::FETCH_BOTH
public function fetch( $fetch_style = PDO::FETCH_CLASS,$cursor_orientation = PDO::FETCH_ORI_NEXT,$cursor_offset = 0 )
{
// make sure we're really dealing with the correct fetch style
if( $fetch_style == PDO::FETCH_CLASS )
{
// then automatically set the fetch mode of this statement
parent::setFetchMode( $fetch_style,$this->fetch_class );
}
// go ahead and fetch,we should be good now
return parent::fetch( $fetch_style,$cursor_orientation,$cursor_offset );
}
}
$db = new PDO( /* etc... */ );
// set default fetch mode to FETCH_CLASS
$db->setAttribute( PDO::ATTR_DEFAULT_FETCH_MODE,PDO::FETCH_CLASS );
// override what statement class to use,and provide constructor arguments (found out by trial and error)
$db->setAttribute( PDO::ATTR_STATEMENT_CLASS,array( 'PDOStatementWithClass',array( 'Db_Row' ) ) );
这样做的另一个好处是,您只需在应用程序中定义一次PDO :: FETCH_CLASS,而不是在每个查询中定义.
