我正在尝试使用一个对象从 mysql 数据库中获取数据,该对象实际上是一个变量:
try {
$mysqlcon = new PDO($dbserver, $db['user'], $db['pass'], $dboptions);
// Selecting database "user" to get data about a specific client
if(($user_data = $mysqlcon->query("SELECT * FROM $dbname.user;")->fetchAll(PDO::FETCH_UNIQUE|PDO::FETCH_ASSOC)) === false)
{
echo '$#!+ happens, Critical DataBase Error!';// error on db select
}
echo 'Country: '.$user_data[$clientuid]['nation']; // This is not working, it gives nothing
echo 'Country: '.$user_data['OISnyJzyjA63XkPB6xla8hjms3M=']['nation']; // BUT This works perfectly
// DEBUGGING
echo $clientuid; // it outputs: OISnyJzyjA63XkPB6xla8hjms3M=
var_dump($clientuid); // and this is the important thing, it outputs this: object(TeamSpeak3_Helper_String)#27 (2) { ["string":protected]=> string(28) "OISnyJzyjA63XkPB6xla8hjms3M=" ["position":protected]=> int(0) }
}
catch (PDOException $e)
{
echo "Database Connection failed: ".$e->getMessage()."\n";
exit;
}
echo $clientuid;
输出:OISnyJzyjA63XkPB6xla8hjms3M=
这不起作用,它什么也没给出:
echo 'Country: '.$user_data[$clientuid]['nation'];
这非常有效:
echo 'Country: '.$user_data['OISnyJzyjA63XkPB6xla8hjms3M=']['nation'];
var_dump($clientuid);
产生这个:
object(TeamSpeak3_Helper_String)#27 (2) {
["string":protected]=> string(28) "OISnyJzyjA63XkPB6xla8hjms3M="
["position":protected]=> int(0)
}
最佳答案
$user_data
是一个对象并且有一个 protected
字符串属性和一个神奇的 __tostring()
方法,当对象作为字符串访问(如 echo
)。如果没有 __tostring()
方法,您将得到:
Recoverable fatal error: Object of class TeamSpeak3_Helper_String could not be converted to string
如果字符串属性是 public
那么你可以直接访问它:
echo 'Country: '.$user_data[$clientuid->string]['nation'];
但是它是protected
并且不可访问,你会得到:
Fatal error: Uncaught Error: Cannot access protected property TeamSpeak3_Helper_String::$string
当用作数组索引时,它不会强制使用字符串,因此要强制它触发 __tostring()
魔术方法,转换为 (string)
将起作用(虽然可能有几种方法可以做到这一点):
echo 'Country: '.$user_data[(string)$clientuid]['nation'];
或使用引号:
echo 'Country: '.$user_data["$clientuid"]['nation'];
关于php - 使用变量从 mysql 数据库获取数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/49056554/