How are additional pages created in Wordpress plugins?

Question

CMS

I came to the conclusion that it is better to implement most things right away through the creation of plugins. I started to research the issue and got stuck on this topic:
I created the main page of the plugin through add_menu_page and also created the submenu add_submenu_page. Both functions are displayed in the admin, but I need to create a page like custom post types, where I could create new elements and on which they would be displayed and worked with in the future. From what I could understand myself, this kind of page works via GET if I'm not mistaken (I looked at the example of creating tags in a post and changing the url line), that is, as I understand it, it just
outputs what is asked for and no standard function WP doesn't have such pages to sculpt and everything is done through php processing?

Answer 1

If I understand correctly, you need custom post types and custom taxonomies .
Comment code:

add_action('init', 'register_posttype');
function register_posttype() {
        $labels = array(
            'name' => __('Shortcodes', 'dco-sm'),
            'singular_name' => __('Shortcode', 'dco-sm'),
            'menu_name' => __('Shortcodes', 'dco-sm'),
            'all_items' => __('DCO Shortcodes Menu', 'dco-sm'),
            'add_new' => __('Add New', 'dco-sm'),
            'add_new_item' => __('Add New Shortcode', 'dco-sm'),
            'edit' => __('Edit'),
            'edit_item' => __('Edit Shortcode', 'dco-sm'),
            'new_item' => __('New Shortcode', 'dco-sm'),
            'view' => __('View', 'dco-sm'),
            'view_item' => __('View Shortcode', 'dco-sm'),
            'search_items' => __('Search Shortcode', 'dco-sm'),
            'not_found' => __('No Shortcodes found', 'dco-sm'),
            'not_found_in_trash' => __('No Shortcodes found in Trash', 'dco-sm'),
        );

        $args = array(
            'labels' => $labels,
            'description' => __('Custom post type for DCO Shortcodes Menu', 'dco-sm'),
            'public' => false,
            'show_ui' => true,
            'show_in_rest' => false,
            'has_archive' => false,
            'show_in_menu' => 'myplugin-admin.php',
            'show_in_admin_bar' => false,
            'exclude_from_search' => false,
            'capability_type' => 'post',
            'map_meta_cap' => true,
            'hierarchical' => false,
            'rewrite' => false,
            'query_var' => false,
            'supports' => array('title'),
        );
        register_post_type('dco_shortcode', $args);
    }

function wpdocs_register_my_custom_menu_page() {
    add_menu_page(
        __( 'Custom Menu Title', 'textdomain' ),
        'custom menu',
        'manage_options',
        'myplugin-admin.php',
        '',
        plugins_url( 'myplugin/images/icon.png' ),
        6
    );
}
add_action( 'admin_menu', 'wpdocs_register_my_custom_menu_page' );

Screenshot of the admin .

Answer 2

Well, you either work through Custom Post Type / Custom Taxonomy, with their native pages and UI, or make your own pages and build your tables using the WP_List_Table class class . Why bother with a hybrid of a rhinoceros and a hippopotamus? Or explain the specific use case of your plugin, because it seems to me that you are still doing something wrong due to a lack of understanding of the core of WP.