pass $post_id to filters in sanitize_post_field() on post updates - same for users, etc.

[whoismanu]

the function sanitize_post_field in wp-includes/post.php calls most of the "database writes" post filters (e.g. content_save_pre). if a post is updated or created, the function is called in a database context ('db' == $context) and the $post_id argument is not passed to the "database writes" filters. while i understand this behavior on post creation ($post_id not yet available) it seems to me that on a post update the $post_id is readily available and could/should be passed to the filters as well.

an example where this would be useful is a case where i want to access a custom field value of a post that is currently being updated from the function hooked into content_save_pre. in its current form without the $post_id argument this doesn't seem to be possible.

the same holds for users and other pieces of data.

what's usually done instead is you post-process the post (on the save_post hook)

It shouldn't hurt anyone and in some cases might prove to be useful