I think I have a problem understanding how OOP works. I've changed the code so it works, but it's not the right way I think. The following scenario (no, I'm not creating the user login myself, it's really just for local developers to understand OOP better):
I have a database.php file:
class Database {
/* Properties */
private $conn;
private $dsn = 'mysql:dbname=test;host=127.0.0.1';
private $user = 'root';
private $password = '';
/* Creates database connection */
public function __construct() {
try {
$this->conn = new PDO($this->dsn, $this->user, $this->password);
} catch (PDOException $e) {
print "Error!: " . $e->getMessage() . "";
die();
}
return $this->conn;
}
}
So in this class I create a database connection and return that connection (object?)
Then I have the second class, the famous User class (actually I don't use autoloading, but I know about it):
include "database.php";
class User {
/* Properties */
private $conn;
/* Get database access */
public function __construct() {
$this->conn = new Database();
}
/* Login a user */
public function login() {
$stmt = $this->conn->prepare("SELECT username, usermail FROM user");
if($stmt->execute()) {
while($rows = $stmt->fetch()) {
$fetch[] = $rows;
}
return $fetch;
}
else {
return false;
}
}
}
These are my two courses. As you can see, no big deal. Now, don't get confused by the function name login - actually I'm just trying to select some usernames and usermails from the database and display them. I try to achieve this by:
$user = new User();
$list = $user->login();
foreach($list as $test) {
echo $test["username"];
}
Here comes the problem. When I execute this code I get the following error message:
Uncaught Error: Call to undefined method Database::prepare()
And I'm not sure I really understand what causes this error.
The code runs fine when I change the following:
Change $conn in database.php to public instead of private (I think this is bad...? But when it is private, I can only do it in the database class Query is executed internally, am I right? So I should put all these queries in database class? I think this is bad because in a big project it will become very big..)
The second change I want to make is:
Change $this->conn->prepare in the user.php file to $this->conn->conn->prepare. Here I really don't know why.
I mean, in the constructor of user.php I have a $this->conn = new Database() and since new Database will be The DB class returns my connection object, I really don't know why there has to be a second conn->
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Databaseclass as it is useless. It makes sense to create a database wrapper if it adds some extra functionality to PDO. But given its current code, it's better to use plain PDO.Database.php：
\PDO::ERRMODE_EXCEPTION, \PDO::ATTR_DEFAULT_FETCH_MODE => \PDO::FETCH_ASSOC, \PDO::ATTR_EMULATE_PREPARES => false, ]; $pdo = new \PDO($dsn, $user, $pass, $opt);user.php
conn = $pdo; } /* List all users */ public function getUsers() { return $this->conn->query("SELECT username, usermail FROM user")->fetchAll(); } }app.php
include 'database.php'; $user = new User($pdo); $list = $user->getUsers(); foreach($list as $test) { echo $test["username"],"\n"; }Output:
Check out my (the only correct) PDO tutorial for more PDO details.