How to get post ID in post_updated action hook?

Question

I want to execute a function, myfunction() [hypothetically named], whenever a page is updated in the admin. The function doesn't do anything to the content that is saved—it just runs an unrelated task elsewhere.

I read that the post_updated hook is good to use for this, but I cannot seem to get this code to run:

add_action('post_updated', 'myfunction');

function myfunction() {
    // check if this is a page
    $id = get_the_id();
    if ( is_page($id) ) {
        // do stuff here
    }
}

I'm sure I'm missing something obvious; do I have to pass in/return parameters ($post_ID, $post_after, $post_before, from what I gather in the Wordpress Hooks Database) for it to work? If I just want the ID, do I still have to pass in/return the other two?

Answer 1

You should be able to get the ID of the post through the $_POST variable.

EDIT: Maybe you should try doing this on the save_post action, like so, but save_post sometimes runs on other instances (ie. Autosave Drafts), so you'll want to do some more verifying. save_post will also return the ID as one of the function arguments so you already have that handy.

add_action('save_post', 'myfunction');

function myfunction( $id ) {

    // verify if this is an auto save routine. 
    // If it is our form has not been submitted, so we dont want to do anything
    if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) 
        return;

    // check if this is a page
    if ( 'page' == $_POST['post_type'] ) {

        // Return nothing if the user can't edit this page
        if ( !current_user_can( 'edit_page', $id ) )
            return;

        // do stuff here, we have verified this is a page and you can edit it

    }

}

Just tested this on localhost, works good for me.

Used a bit of code from here and you should read up on the save_post action if you decide to try this out!

Answer 2

get_the_ID() should work, I use it for a very similar purpose.

The hooks I use it on are

add_action('future_to_publish','123_total_calculator');
add_action('new_to_publish','123_total_calculator');
add_action('draft_to_publish','123_total_calculator');
add_action('publish_post','123_total_calculator');