当第一个数组键未知时,如何在第一个数组键的开头添加:？

Question

我正在尝试将类属性动态添加到PDO预处理语句中.为了实现这一点,我需要创建一个数组,它将从类中获取属性,将它们放在一个数组中,并在每个键的开头添加:.然后,用逗号分隔每个键.我最接近实现这一点的是使用:

foreach ($property as $field)
   $propertyValues = implode(", :", array_keys($property));
return $propertyValues;
}  

它给了我
用户名,:密码

我只需要一种方法来添加:到第一个键,在这种情况下是用户名.看起来就像

:用户名密码

但请记住,我正在尝试使其动态化,以便我可以将其功能扩展到其他类,并且我并不总是会知道第一个数组键是什么.

如果您有兴趣阅读整个班级,请点击此处:

<?php 
require_once("../config/main.php");

class Database{

protected static $dbFields = array('username', 'password');
public $dbConnection;
public $tableName = 'users';
public $id;
public $username;
public $password;
public function __construct() {
$this->connect();
}

public function connect(){
try {
$this->dbConnection = new PDO("mysql:host=".DB_SERVER."; dbname=".DB_NAME, DB_USER,  DB_PASS);

} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}
}
public function properties() {
$properties = array();
foreach (self::$dbFields as $field) {
    if (isset($this->field) || property_exists($this, $field)) {
        $properties[$field] = $this->$field;
    }
}
return $properties;
}

public function property_values() {  

$property = $this->properties();

    $propertyValues = implode(", :", array_keys($property));

return $propertyValues;
}

public function insert(){
    // this is where all the is going to happen. it's a work in progress
// $sql  = "INSERT INTO". $this->tableName. " (";
// $sql .= implode(", ",array_keys($this->properties()));
// $sql .= ")VALUES(". ;


// $q = $this->db->prepare($sql);
// $q->execute(array('John', 'hula'));
}


}

$database = new Database();
$vals = $database->property_values();
print_r($vals);

?>

Answer 1

$propertyValues = ':'. implode(", :", array_keys($property));