Simple plugin don't display content

Question

Trying to learn WP plugin development.

Followed all the instructions.

plugins/e4-test-1 directory.

Main php file (e4-test-1.php):

<?php
/**
 * Plugin Name: Test 1
 * Plugin URI: http://xxxxx.xxx
 * Description: xxxxxxxxxxxxxxxxxx
 * Version: 1.0.0
 * Author: xxxxxxx
 * Author URI: http://xxxxxx.xxx
 * License: GPL2
 */

My one an only php file with code (testhook.php):

<?php

function testhook() {
     echo 'SOULISSSSSSSSSSSS';
}
add_action( "wp_head", "testhook" );

It simply does nothing. View Source doesnot contain the string anywhere.

Of course I have activated the plugin, cleared caches e.t.c

Obviously my noobness stops me from finding the mistake

Answer 1

You need to call your custom file into your main plugin file. Without doing that, your custom file will not get called. Think of your main plugin file as your themes functions.php file and your custom file like a custom file that also holds functions

By default, Wordpress will only read your functions.php, and not your custom functions file. For wordpress to know to load that functions inside the custom file, you need to tell wordpress that there is a custom file with functions it should load. Normally, in a theme, you would use include or require_once. Here we would do the same, except, your path will differ from themes

So you can try the following in your main plugin file

require_once(dirname(__FILE__) . '/testhook.php');

Answer 2

Try to activate the debug mode in config.php: Set this to true:define('WP_DEBUG', false);

Deactivate any plugin you have running to make sure there isn't a Jquery error.

Now run it again. Maybe you should also start with something simpeler. The tag <script> wants to run something. Maybe your browser doesn't allow it (for what kind of reason)

Try following:

function testhook() {
   echo'TEST';
}
add_action( "wp_head", "testhook" );