范围错误-在非对象上调用成员函数prepare() [英] Scope error - Call to a member function prepare() on a non-object
问题描述
所以场景很简单.我使用的类在数据库中执行某些操作，但在该类中，我调用了另一个在数据库中也执行某些操作的类.
谢谢，include_once已更改为include，并且可以使用！
这就是我得到的:
致命错误:调用成员函数 对非对象的prepare()->第20行的 mLog.php
我使用db_config.php创建PDO对象，然后将其包含在我的类中.
db_config.php
try
{
$DBH = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
$DBH->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
}
catch (PDOException $e)
{
echo $e->getMessage();
}
第一类 mLog.php
<?php
class Log
{
public static function Add($action)
{
try
{
include_once "db_config.php";
$ip = $_SERVER['REMOTE_ADDR'];
$time = date('Y-m-d');
$values = array($ip, $action, $time);
//ERROR NEXT LINE
$STH = $DBH->prepare("INSERT INTO log (ip, action, time)
VALUES (?, ?, ?)");
$STH->execute($values);
$DBH = null;
$STH = null;
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
}
使用头等舱的二等舱(碎片，因为它很大并且具有许多功能)
public static function Add($catName, $catDescr = "", $catImgURL = "", $catSubLevel = 0, $catSubID = 0)
{
try
{
include_once "db_config.php";
include_once "mLog.php";
$values = array($catName, $catDescr, $catImgURL, $catSubLevel, $catSubID);
$STH = $DBH->prepare("INSERT INTO cat (catName, catDescr, catImg, catSubLevel, catSubID)
VALUES (?, ?, ?, ?, ?)");
$STH->execute($values);
$DBH = null;
$STH = null;
//HERE IT IS
Log::Add("Added category 111" . $catName);
return true;
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
您使用的是include_once "db_config.php";而不是include "db_config.php";.
据我从代码中了解，每次包含db_config.php时，您都会创建数据库对象$DBH.
由于将其设置为include_once，因此它将仅运行db_config.php一次，并且在尝试包含它时在日志类中将使其不运行-因为它已经包含在Add方法中. /p>
要对此进行改进，您应该创建一个仅管理(或封装)PDO对象的类.您可以简单地创建一个返回PDO对象的Singleton类，将该类放在顶部一次，然后在代码中的任何位置获取该对象.
示例:
DBAccess.php
class DBAccess extends Singleton{
// there is a getInstance() method in the Singleton abstract class
private $dbh;
// The PDO object is created only once when the first getInstance() is called in Singleton.
function __construct(){
try
{
$this->dbh = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
$this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
/**
* Get the PDO object
* @return object
*/
public static function getDBH(){
return self::getInstance()->dbh;
}
}
日志类别:
class Log
{
public static function Add($action)
{
try
{
$DBH = DBAccess::getDBH();
$ip = $_SERVER['REMOTE_ADDR'];
$time = date('Y-m-d');
$values = array($ip, $action, $time);
$STH = $DBH->prepare("INSERT INTO log (ip, action, time)
VALUES (?, ?, ?)");
$STH->execute($values);
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
}
用法:
include_once('db_config.php'); include_once('mLog.php');
public static function Add($catName, $catDescr = '', $catImgURL = '', $catSubLevel = 0, $catSubID = 0)
{
try
{
$DBH = DBAccess::getDBH();
$values = array($catName, $catDescr, $catImgURL, $catSubLevel, $catSubID);
$STH = $DBH->prepare("INSERT INTO cat (catName, catDescr, catImg, catSubLevel, catSubID)
VALUES (?, ?, ?, ?, ?)");
$STH->execute($values);
$DBH = null;
Log::Add("Added category 111" . $catName);
return true;
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
So the scenario is simple. I use class that does something in database but in that class I call another class that also does something in DB.
Thanks, include_once changed to include and it works!
This is what I get:
Fatal error: Call to a member function prepare() on a non-object -> mLog.php on line 20
I use db_config.php to create PDO object and then include it in my classes.
db_config.php
try
{
$DBH = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
$DBH->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
}
catch (PDOException $e)
{
echo $e->getMessage();
}
1st class mLog.php
<?php
class Log
{
public static function Add($action)
{
try
{
include_once "db_config.php";
$ip = $_SERVER['REMOTE_ADDR'];
$time = date('Y-m-d');
$values = array($ip, $action, $time);
//ERROR NEXT LINE
$STH = $DBH->prepare("INSERT INTO log (ip, action, time)
VALUES (?, ?, ?)");
$STH->execute($values);
$DBH = null;
$STH = null;
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
}
second class that uses first class (fragment because it's big and has many functions)
public static function Add($catName, $catDescr = "", $catImgURL = "", $catSubLevel = 0, $catSubID = 0)
{
try
{
include_once "db_config.php";
include_once "mLog.php";
$values = array($catName, $catDescr, $catImgURL, $catSubLevel, $catSubID);
$STH = $DBH->prepare("INSERT INTO cat (catName, catDescr, catImg, catSubLevel, catSubID)
VALUES (?, ?, ?, ?, ?)");
$STH->execute($values);
$DBH = null;
$STH = null;
//HERE IT IS
Log::Add("Added category 111" . $catName);
return true;
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
You used include_once "db_config.php"; instead of include "db_config.php";.
As I understand from your code, each time you include db_config.php, you will create the database object $DBH.
Since you put it as include_once, it will only run db_config.php once, and in the log class when you try to include it, it will not run - since it has already been included in the Add method.
To improve on this, you should create a class that solely manages (or encapsulate) the PDO object. You can simply create a Singleton class that returns the PDO object, include the class once at the top, and fetch the object where ever you are in the code.
Example:
DBAccess.php
class DBAccess extends Singleton{
// there is a getInstance() method in the Singleton abstract class
private $dbh;
// The PDO object is created only once when the first getInstance() is called in Singleton.
function __construct(){
try
{
$this->dbh = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
$this->dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
/**
* Get the PDO object
* @return object
*/
public static function getDBH(){
return self::getInstance()->dbh;
}
}
Log Class:
class Log
{
public static function Add($action)
{
try
{
$DBH = DBAccess::getDBH();
$ip = $_SERVER['REMOTE_ADDR'];
$time = date('Y-m-d');
$values = array($ip, $action, $time);
$STH = $DBH->prepare("INSERT INTO log (ip, action, time)
VALUES (?, ?, ?)");
$STH->execute($values);
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
}
Usage:
include_once('db_config.php'); include_once('mLog.php');
public static function Add($catName, $catDescr = '', $catImgURL = '', $catSubLevel = 0, $catSubID = 0)
{
try
{
$DBH = DBAccess::getDBH();
$values = array($catName, $catDescr, $catImgURL, $catSubLevel, $catSubID);
$STH = $DBH->prepare("INSERT INTO cat (catName, catDescr, catImg, catSubLevel, catSubID)
VALUES (?, ?, ?, ?, ?)");
$STH->execute($values);
$DBH = null;
Log::Add("Added category 111" . $catName);
return true;
}
catch (PDOException $e)
{
echo $e->getMessage();
}
}
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