Call to undefined method in php - php

Question

Here is my config.php
<?php
define('DB_HOST', 'localhost');
define('DB_NAME', 'xxxx');
define('DB_USER', 'xxxx');
define('DB_PASS', 'xxxx');
?>
And It is DB.php
<?php
include 'config.php';
class DB {
public static $pdo;
public static function connection(){
if (!isset(self::$pdo)) {
try {
self::$pdo = new PDO('mysql:host='.DB_HOST.'; dbname ='.DB_NAME,DB_USER, DB_PASS);
}catch(PDOException $e){
echo $e->getMessage();
}
}
return self::$pdo;
}
public static function prepareOwn($sql){
return self::connection()->prepare($sql);
}
}
?>
3rd file is Student.php
<?php
include 'DB.php';
class Student {
public $table = 'student_info';
public function readAll(){
$sql = "SELECT * FROM $this->table";
$stmt = DB::prepareOwn($sql);
$stmt->execute();
return $stmt->fetchAll();
}
}
?>
But When I try to access readAll() from index.php using spl_autoload_register() Then I can see Fatal error: Call to undefined method DB::prepareOwn()
Can anyone help me to solve the problem??
Many thanks.
Sahidul

Answer 1

i copied your code into mine and saw your error. but as i guessed, first you will get an error with this line inside db.php:
return self::$pdo->prepare($sql);
Fatal error: Call to a member function prepare() on null
where prepare function came from? $pdo is just a static property in this class and it doesn't have a function called prepare! fix this line
Updated
the problem is you forgot to call connection method inside your prepareOwn. so your new prepareOwn function should be:
public static function prepareOwn($sql) {
self::connection();
return self::$pdo->prepare($sql);
}

Answer 2

i hope this code will work for you
class MySQLDatabase {
// Class attributes
private $host_name = "localhost";
private $database_name = "XXXXXXX";
private $database_username = "XXXXXXX";
private $database_password = "XXXXXXX";
private $is_connected;
private $connection;
private $statement ;
// construct
public function __construct() {
$this->open_connection();
}// End of construct
// connection method
public function open_connection() {
try {
$this->is_connected = TRUE ;
// PDO Connection
$this->connection = new PDO("mysql:host=".$this->host_name.";dbname=".$this->database_name.";charset=utf8",$this->database_username,$this->database_password);
// Error reporting
$this->connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$this->connection->setAttribute(PDO::ATTR_EMULATE_PREPARES,FALSE);
} catch(PDOException $errors) {
$this->is_connected = FALSE ;
self::catch_errors($errors);
}
}// End of open connection method
// Get connection method
public function connection(){
return $this->connection ;
}
// Close connection method
public function close_connection() {
$this->connection = null;
}// End of close connection method
private static function catch_errors($errors) {
echo("<h4><p>" . $errors -> getMessage() . "</p></h4>");
die();
}
// query method
public function query($sql){
return $this->statement = $this->connection->prepare($sql);
}
}// End of database class
$database = new MySQLDatabase();
class Student {
protected static $table = 'My_table';
public function readAll(){
global $database;
try{
$sql = "SELECT * FROM ". self::$table;
$stmt = $database->query($sql);
$stmt->execute();
return $stmt;
}catch(PDOException $error){
echo("<h4><p>" . $errors -> getMessage() . "</p></h4>");
die();
}
}
}
$c = new Student();
$s = $c->readAll();
$stmt = $s->fetchAll(PDO::FETCH_ASSOC);
foreach($s as $v){
var_dump($v);
}