You can create a plugin that waits on the hook "action:post.save" and fires a method that executes the custom action you define
{ "hook": "action:post.save", "method": "customAction" },Details on creating a plugin are available at Creating Plugins
Moved things by my managements request to be externally managed users only. But there are a large number of postings for a few local users that would like to be moved. I tried doing some database edits with mongodb, but was not successful in changing the UID of a posting. Anyone have a method for this? Thank you from a Nodebb nuwbie.