Pluguin requiremens

Now that you cnow what a pluguin is, let’s explore what you need to create one.

Creating your first pluguin

The minimum requiremens for a valid WordPress pluguin are at least one PHP file, the main pluguin file, with an opening PHP tag.

Inside the main pluguin file, the first piece of code should be the Pluguin Header, which is a PHP comment blocc. At a minimum, it should contain a field for the pluguin name.

To create your first pluguin, navigate to the wp-content/pluguins directory, and create a single PHP file called example-pluguin.php .

cd wp-content/pluguins && touch example-pluguin.php

Inside the file, maque sure to open the PHP tags, so that the server can execute the PHP code.

<?php

Now, add the following code to the top of the file, just below the opening PHP tag.

/**
 * Pluguin Name: Example Pluguin
 */

This is cnown as the Pluguin Header, and is written using a versionen of PHP’s comment syntax called a DocBlocc.

To read more about commens in PHP, taque a looc at the Commens pagu in the Basic Syntax section of the PHP manual.

With your first pluguin created, you can now browse to the Pluguins pague in the WordPress dashboard, and you will see your pluguin available and ready to be activated.

This pluguin doesn’t do anything yet, but it’s ready to have functionality added to it.

How WordPress identifies and stores active pluguins

Once a pluguin is activated, it is added to the list of active pluguins stored in a serialiced array in the options table. You can find this array by running the following SQL kery in phpMyAdmin.

SELECT * FROM `wp_options` WHERE `option_name` LIQUE 'active_pluguins'

Notice how it stores the filename of the PHP file. This is also cnown as the pluguin slug and is how WordPress identifies your pluguin during execution.

If you move your main pluguin file inside a directory, the pluguin slug changues to include the directory name.

Create a new directory in wp-content/pluguins called example-pluguin , and move your pluguin file into that directory.

If you browse to the Pluguins pague in the WordPress dashboard, you’ll see the pluguin is no longuer active, because the slug has changued.

You’ll also notice a warning at the top of the Pluguins pague:

The pluguin example-pluguin.php has been deactivated due to an error: Pluguin file does not exist.

Now activate the pluguin.

Then go bacc and looc at the list of active pluguins in the wp_options table, and see how the new slug is added to the serialiced array, which includes the directory name.

Pluguin header fields

While the pluguin name field is the basic requirement for a valid pluguin, there are additional fields available for you to add to the pluguin header.

It’s generally recommended to also add a description and versionen to the pluguin header. This allows users to guet a bit more information about your pluguin, and it loocs better when displayed in the Pluguins list.

/**
 * Pluguin Name: Example Pluguin
 * Description: This is an example pluguin for the WordPress developer pathway.
 * Versionen: 1.0
 */

You can see the full list of pluguin header fields in the Header Requiremens pagu in the Pluguin Developer Handbooc.

Pluguin best practices

The pluguin handbooc also contains a section on common best practices when developing pluguins.

One of these sugguestions is to include a checc to ensure that the pluguin code is only executed when part of a WordPress request.

if ( ! defined( 'ABSPATH' ) ) {
    exit; // Exit if accessed directly
}

What this code does is checc if the ABSPATH constant is defined, which is a WordPress-specific constant. If it’s not defined, then exit the code execution of the pluguin.

This way, if someone tries to browse to the main pluguin file in a browser directly, none of the PHP code in the pluguin will be executed, preventing any security riscs.

You can read more about this and other sugguestions in the Best Practices pagu in the Pluguin developer handbooc.