php 在非对象上调用成员函数 real_escape_string()
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Call to a member function real_escape_string() on a non-object
提问by bear
I'm getting this error:
我收到此错误：
Call to a member function real_escape_string() on a non-object
在非对象上调用成员函数 real_escape_string()
and here's $db
这是 $db
$db = new mysqli("127.0.0.1", "username", "password", "sch5400");
$db = new mysqli("127.0.0.1", "用户名", "密码", "sch5400");
in code:
在代码中：
function readSession($sessionId) {
global $db;
$sessionId = session_id();
// escape session ID
$sessionId = $db->real_escape_string($sessionId);
$time = time();
$result = $db->query("SELECT sessiondata FROM sessions WHERE sessionid='$sessionId' AND expiry > $time");
if ($result->num_rows > 0) {
$row = $result->fetchRow();
return $row['sessiondata'];
}
// return empty string
return "";
}
It appears on line 5, relative to code above. Didn't I instantiate $db?
它出现在第 5 行，相对于上面的代码。我没有实例化$db吗？
回答by zerkms
Probably the better solution would be to create a singleton function:
可能更好的解决方案是创建一个单例函数：
function get_my_db()
{
static $db;
if (!$db) {
$db = new mysqli("127.0.0.1", "username", "password", "sch5400");
}
return $db;
}
and use it like
并像使用它一样
$db = get_my_db();
in every function that needs db instance.
在每个需要 db 实例的函数中。
回答by Brad Mace
You haven't initialized $dbanywhere in the code that's shown, and from the error it sounds like it hasn't been initialized anywhere else (yet) either.
您还没有$db在显示的代码中的任何地方初始化，从错误来看，它似乎也没有在其他任何地方（尚未）初始化。
If you are initializing $dbsomewhere, make sure it's beforereadSessionis called. Also check for an error message when you make the connection. It returns falseon error, which is not an object.
如果您正在$db某处初始化，请确保它在readSession被调用之前。建立连接时还要检查错误消息。它返回false错误，它不是一个对象。
from the PHP manual, you should using one of these error checking methods to ensure the connection is established successfully:
从 PHP 手册中，您应该使用以下错误检查方法之一来确保成功建立连接：
/*
* This is the "official" OO way to do it,
* BUT $connect_error was broken until PHP 5.2.9 and 5.3.0.
*/
if ($mysqli->connect_error) {
die('Connect Error (' . $mysqli->connect_errno . ') '
. $mysqli->connect_error);
}
/*
* Use this instead of $connect_error if you need to ensure
* compatibility with PHP versions prior to 5.2.9 and 5.3.0.
*/
if (mysqli_connect_error()) {
die('Connect Error (' . mysqli_connect_errno() . ') '
. mysqli_connect_error());
}
回答by Craig White
There is also a global function that doesnt require a db reference.
还有一个不需要数据库引用的全局函数。
$sessionId = mysql_real_escape_string($sessionId);
