Per Post Type Revision Numbers

Question

In wp-config.php you're able to change how WordPress deals with post revisions. Specifically you're able to turn them off or specify a max number of revisions.

I'd like to be able to set a max number or revisions on a post type basis.

Is this possible?

Answer 1

1. Remove the action 'wp_save_post_revision' from 'pre_post_update'. It is set per default in wp-includes/default-filters.php with the default priority (10).

2. Add your own function to this hook. You get the $post_ID as parameter, so detecting the post type is easy.

3. In your callback copy the code from wp_save_post_revision() but use the constant WP_POST_REVISIONS for the post type post only, and use different values for other post types. Not sure if it is possible to pass extra values in register_post_type() …

Answer 2

This is possible but it's not as simple as changing the WP_POST_REVISIONS property in the wp-config.php. This is possible by adding a filter to the 'wp_insert_post_data'.

Adding a filter is done like this:

add_filter('wp_insert_post_data' , 'my_insert_post_data');

function my_insert_post_data($data , $postarr) {
  // Check the revision stuff
  return $data;
}

Answer 3

after 11 years of the question, today I stumbled upon this question and here is my solution:

// keep 10 revisions for only posts.
// /wp-includes/revision.php:621
// filter: wp_{$post->post_type}_revisions_to_keep
add_filter('wp_post_revisions_to_keep', 'postRevisionsToKeep');
function postRevisionsToKeep(): int
{
    return 10;
}