How to build custom plugin to integrate with current theme - wordpress

Question

I am developing a plugin with a CPT and a CPT template. I would like the template to be able to integrate into any theme it is used with. I thought of calling the 'the_content' hook from my template but I have no idea how to do that as all I can find is calling it from the functions.php file. Please can you tell me how to code this in the CPT template file (like single-CPT.php) or maybe I am heading in the wrong direction so please redirect me. Thank you!

Answer 1

EDIT:
If you only want to add content to the_content function you can do something like that:
add_filter('the_content', "test_the_content");
function test_the_content($content){
if(is_singular('test')){
$content = $content.test_additional_content();
}
return $content;
}
function test_additional_content(){
ob_start(); ?>
<div class="test">
Here what you want to display after the_content
</div>
<?php
return ob_get_clean();
}
ORIGINAL ANSWER
If I understood your question correctly, here is how to define the templates of your custom post type in your plugin. This way it will also be possible to overwrite the plugin template from the theme.
The example below is for a CPT called "test", so you have to adapt the code according to the name of your CPT.
add_filter('template_include', 'my_plugin_templates');
function my_plugin_templates($template) {
$post_types = array('test');
if (is_post_type_archive($post_types) && !file_exists(get_stylesheet_directory() . '/archive-test.php')) {
$template = plugin_dir_path( __FILE__ ) . 'archive-test.php';
}
if (is_singular($post_types) && !file_exists(get_stylesheet_directory() . '/single-test.php')) {
$template = plugin_dir_path(__FILE__) . 'single-test.php';
}
return $template;
}
You can also take a look to this repo: https://github.com/zecka/cpt-in-plugin