add_submenu_page not working

Question

I have a built a plugin which creates a custom menu like this:

    add_menu_page( 'Wholesale Pricing', 'Wholesale', 'manage_options', 'woo-wholesale', 'woo_wholesale_page_call'); 

I am now trying to add a subpage item underneath this. I have read the codex and came up with:

add_submenu_page( 'woo-wholesale', 'Registrations', 'Registrations', 'manage_options', 'woo-wholesale-registrations', 'wwpr_page_call' ); 

I am guessing this is incorrect as the submenu item isnt showing. Can anyone shed any light on this please?

Answer 1

Make sure that your add_action hook is set to admin_menu.

Here's a sample code:

add_action('admin_menu', 'wpse149688');
function wpse149688(){
    add_menu_page( 'Wholesale Pricing', 'Wholesale', 'manage_options', 'woo-wholesale', 'woo_wholesale_page_call');
    add_submenu_page( 'woo-wholesale', 'Registrations', 'Registrations', 'manage_options', 'woo-wholesale-registrations', 'wwpr_page_call' ); 
}

Also check whether user you've logged in as has the ability to view this menu. As this menu is set using manage_options capability.

Answer 2

I made the same mistake as the OP as it is not intuitive how to get this working. By reading the codex on Administration Menus, I discovered the answer.

The problem (for me, anyway) was to edit the $parent_slug parameter in the call to add_submenu_page(...).

So, in the OP's case, you would change:

add_submenu_page( 
    'woo-wholesale', 
    'Registrations', 
    'Registrations', 
    'manage_options', 
    'woo-wholesale-registrations', 
    'wwpr_page_call' 
);

to:

add_submenu_page( 
    'edit.php?post_type=woo-wholesale', 
    'Registrations', 
    'Registrations', 
    'manage_options', 
    'woo-wholesale-registrations', 
    'wwpr_page_call' 
);

Answer 3

Your code is correct. However there is something missing which it is not obvious at all, and whoever comes to this question again in the future, you should read this:

When a menu page has 0 or 1 submenu pages, no submenus will show up.

A menu page contains a page by itself.

A menu page that contains 1 submenu page, will appear as the same as if it didn't have a submenu page. This is because the first-level menu element and the first second-level menu belonging to that first-level menu are meant to show the same page.

In other words, you can't have a single submenu element, because that doesn't seem to make sense for WordPress.

"Only one page? Just use the menu element itself then! No need for a dropdown."

Notice that whenever you click on a menu item found in the admin interface that has subitems, it will load its first subitem. So the menu item and its first subitem are essentially the same. However, you are able to rename the subitem.

Some examples of this:

• Dashboard = Home
• Posts = All Posts
• Appearance = Themes
• Tools = Available Tools

So in your case clicking on Wholesale Pricing would load Registrations.

When a menu page contains 2 or more submenu pages, the submenu pages will become visible. That's what most of us don't know at first.

So the trick is to create a submenu page identical to the menu page (you can change the $page_title and $menu_title if you want) and then your additional submenu page:

add_menu_page( '', 'Menu Item', $capability, 'parent_slug', $callback );
add_submenu_page( 'parent_slug', 'Page Title', 'First Subitem', $capability, 'parent_slug', $callback );
add_submenu_page( 'parent_slug', 'Second Page Title', 'Second Subitem', $capability, 'submenu_slug', $submenu_callback );

As you can see, the $page_title for add_menu_page could even be left as an empty string (but not null), because the title used for the page will be the first submenu's $page_title. But I recommend to introduce the same string for both for readability.

Now let's apply this to your code:

add_menu_page( 'Wholesale Pricing', 'Wholesale', 'manage_options', 'woo-wholesale', 'woo_wholesale_page_call');
add_submenu_page( 'woo-wholesale', 'Wholesale Pricing', 'Pricing', 'manage_options', 'woo-wholesale', 'woo_wholesale_page_call' );
add_submenu_page( 'woo-wholesale', 'Registrations', 'Registrations', 'manage_options', 'woo-wholesale-registrations', 'wwpr_page_call' );

And you will have the following menu structure:

Wholesale
-- Pricing
-- Registrations

Where clicking on either Wholesale or Pricing will lead you to the same page.

Answer 4

For me it I had for the capabilities manage-options instead of manage_options. That fixed it for me.