How to conditionally include a custom field on category editor screen not category “add” screen

Question

The "manage categories" screen has two interfaces, one when you first click on "Categories" which is used to add a new category and another once you click on an existing category to edit it.

I've added some custom fields to the Category editor, but I only want them to be present on the edit screen, not the "add" screen.

However $pagenow in both cases, is the same (edit-tags.php). The only difference I can see is that when editing, the action=edit token appears on the querystring.

Should I simply wrap my "edit_category_form" filter in a test for the existence of that token or is there a better way?

PS: I'd be fine with leaving the fields on the add screen, however, it appears that the save is ajaxed, and none of my custom fields are being saved in that routine.

Answer 1

You can target edit-tags.php page and additionally check for that edit action.

add_action( 'admin_head-edit-tags.php', 'my_category_edit' );

function my_category_edit() {

    global $action, $taxonomy;

    if( 'edit' != $action || 'category' != $taxonomy )
        return;

    // code goes here
}