Using MySQLi in Classes: A Troubleshooting Guide

Using MySQLi from different classes can be challenging, but don't worry. Let's dive into the issues you've encountered and provide a solution.

Problem: Internal Server Error 500

• Cause: Attempting to access the conn property of the Database object after creating it in a different class (MyAPI).

Solution: Initialize the Database object within the MyAPI constructor and pass it as a parameter to other functions requiring a database connection. This ensures that all classes sharing the connection have a direct reference to the same instance.

Example:

// myapi.php
class MyAPI {
    private $db;

    public function __construct($db) {
        $this->db = $db;
    }

    public function getUser($id) {
        $result = mysqli_query($this->db->conn, "SELECT * FROM users WHERE id='$id'");
        return mysqli_fetch_assoc($result);
    }
}

// app.php
// Initialize database once
$db = new mysqli(...);

// Create MyAPI instance with database reference
$api = new MyAPI($db);

// Use MyAPI to access user information
$user = $api->getUser(1);

Additional Considerations:

• Avoid extending User from Database, as it's not necessary.
• Directly create a single mysqli instance and pass it to classes that need it.
• Use prepared statements for better security and performance.
• Ensure the database connection parameters are correct and the database is accessible.

By following these steps, you should be able to successfully use MySQLi from different classes in PHP.