There are lots of reasons that a WordPress developer might want to customize the post edit screen when developing their plugin or theme. However, using a custom post type is probably the most common reason to customize it. The developer might want to add additional headers, instructions, styles, javascript, or add/remove input fields.

Note that the easiest way to add custom input fields to the WordPress edit screen is to add a metabox. However, if you need more ways to customize it, keep reading! I will even provide some code examples.

Reference List of WordPress Hooks that You can use to Modify the Post Edit Screen

1. in_admin_header

in_admin_header is the hook you want to use if you need to alter the heading of any of the admin screens. It fires at the very top of the page for all admin pages, including the comments page, media page, plugins page, tools page, appearance page, etc. It even fires on custom settings pages and custom post type pages, like the WooCommerce admin screens for products and orders. Like all hooks, this hook is called by the WordPress function do_action. Wordpress core uses this hook to render the WordPress admin bar. I can see using this hook if you want to add a banner along the top of all admin screens.

2. admin_notices

admin_notices is a great hook to use for posting messages at the top of admin screens. Wordpress core makes adding notices extremely easy! Simple use this hook to output a div. Wrap the div in one or more of the following classes to make your notice stand out

For examples, see the Codex page on admin_notices.

.error = This class will make your notice have a white background and red left border

.update_nag = This class will make your notice have a yellow border and move it higher on the page.

.notice and .is-dismissible = This class will make your notice dismissible! A great option if you don’t want to annoy your users. Wordpress core handles adding a close button and removing the notice for you. (See this article on how to make your notices dismissible.)

3. all_admin_notices

There is not much documentation on this hook. I looked at the code and it looks like this should fire in some cases when the admin_notices hook doesn’t fire (for example on the network admin screen for WordPress Multisite). Take a look at WordPress Core for more details (\wp-admin\admin-header.php – around line 228)

4. edit_form_top

This is a hook for adding to the edit screen after the “Add New Post” title. Note that if you want to change the words “Add New Post” for a custom post type, you should do that when registering a new post type. See the arguments that you can add. The array of labels has lots of options. That’s right, you set up those words upon registering the custom post type. There is no need to try to filter it later.

5. edit_form_after_title

This hook is perfect for adding html to the post edit screen after the heading and above the post content box. By the way, the rich text editor you use in WordPress is called TinyMCE, which is an open source HTML WYSIWYG editor.

6. edit_form_after_editor

This fires after the post content editor but before the excerpt, the slug, the author, and other optional/add-on meta boxes.

7. edit_form_advanced

This fires near the very bottom of the edit post screen. It will display your custom HTML after all meta boxes.

Note: This does NOT fire on the edit page screen. It will fire on all other post types.

8. post_submitbox_misc_actions

Want to add a checkbox, dropdown input field, or other input field or text to the publish post box? This is the hook to use! See the Codex for an example.

9. media_buttons

Add a button next to the add media button, for uploading files that your custom plugin or theme deals with in a specialized way. Tutorial for using the media_buttons action hook.

How to Only Make Changes to the Edit Screen for a Custom Post Type?

In the function that you hook, you can check which screen is being displayed, and then only make the custom changes if the screen ID and screen post type are a match. For example:

add_action('in_admin_header', 'in_admin_header_lw'); function in_admin_header_lw() { $screen = get_current_screen(); if($screen->post_type=='post' && $screen->id=='post') { echo "This is the edit post screen."; } }

You actually only need to check the id and not the post_type if you only want to make the changes on one page. But, if you want the change to appear on all pages with the same post_type, then checking the post_type property of the WP_Screen object is the way to go. The function get_current_screen returns a WP_Screen object. Each screen has a unique ID.

Everyone has their own workflow, but my personal preference in figuring out how PHP code works is to use a debugger and put a breakpoint at the location where I want to check the contents of variables. When I did this in PHPStorm, while on the WooCommerce add product screen, I was able to see the contents of the WP_Screen object, therefore making it really obvious what I should be checking for in my code.

How to Add Styles and Scripts to the Post Edit Screen?

Need to add javascript or CSS styles to only one admin screen? Here’s the way to add it (this code assumes that admin-style.css is the name of your CSS file and it’s in the same directory as the plugin file).

add_action( 'admin_enqueue_scripts', 'lw_load_custom_wp_admin_style' ); function lw_load_custom_wp_admin_style() { $screen = get_current_screen(); if( $screen->id=='post') { wp_register_style( 'lsw_custom_wp_admin_css', plugins_url( '/admin-style.css', __FILE__ ), false, '1.0.0' ); wp_enqueue_style( 'lsw_custom_wp_admin_css' ); } }

Questions, Improvements?

Are you puzzled about something? Or did I make an error? If so, please take a moment to comment. Thank you!