I spent ages trying to find out how to do this. I knew it existed because I read about it but had no idea what to look for to find it. So this is a quick reminder write up.

If you write a plugin that creates an admin page, from WordPress 2.6 (I think) there is a new way to deal with the information the user posts from the form.

In the old days the form handling code would go at the top of the admin page function, or it could be hooked into other actions like the template selector. Now WordPress will create a custom hook.

In the admin page add a hidden form field called ‘action’ with a value of {pluginname}_{action}-{object}; so if you are updating a comment you might use ‘myplugin_comment-update’. You also need to change your form so it posts to admin-post.php.

Admin post will load all the WordPress functions and things, then create a custom hook called: ‘admin_post_’ + your action name. So you can create a new function for handling your form data and trigger it (using the same example) with add_action( ‘admin_post_myplugin_comment-update ‘myfunction’);