How Can I Successfully Connect to MySQLi from a Separate Class in PHP and Troubleshoot Connection Errors?

Using MySQLi from Another Class in PHP: Troubleshooting Connection Errors

In PHP, utilizing MySQLi from a separate class can present challenges, particularly when upgrading from older PHP versions. This article addresses common issues and provides solutions to help you establish a successful connection.

Problem Description

The initial implementation of the database connection in a separate class and accessing it in the API class resulted in an internal server error (500) when attempting to query the database.

Solution

Upon investigation, several best practices were overlooked in the original setup:

• Extending a user class from the database class is unnecessary.
• The database class serves no meaningful purpose.

To resolve the issue, consider the following:

1. Eliminating Redundant Database Class

Discard the unnecessary Database class and create a single MySQLi instance instead.

2. Dependency Injection

Provide the MySQLi instance as a constructor parameter to every class that requires a database connection.

3. Example Implementation

database.php:

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$db = new mysqli("localhost", "DBUserName", "UserPassword", "SelectedDB");
$db->set_charset('utf8mb4');

myapi.php:

class MyAPI
{
    protected $db;

    public function __construct($db, $request_uri, $postData, $origin)
    {
        $this->db = $db;
    }

    public function getUser($id)
    {
        $sql = "SELECT * FROM users where>

Tips for Debugging

• Implement PHP error logging to capture any errors or exceptions.
• Verify the database credentials and ensure the required MySQLi extensions are enabled.
• Check the database connection details and ensure you are connecting to the correct database.
• Avoid mixing different database abstraction layers (e.g., MySQL and MySQLi) within the same application.

By adhering to these recommendations, you can establish a robust and maintainable database connection in PHP.

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