Convert Google Docs to PDF on File Change

A scheduled trigger runs at fixed intervals regardless of what changed. An event-driven trigger fires in response to a specific action, such as a file being edited, a new file appearing in a folder, or a form being submitted. Event-driven conversion is better when you want the PDF to be as current as possible and do not want to wait for the next scheduled run.

Apps Script supports installable Drive triggers that fire when files change. An onChange trigger fires when any file in a user's Drive is created, edited, moved, or trashed. You can filter the event by type and by the specific file or folder you care about. Drive triggers are more reliable than polling and respond to changes within a minute.

Zapier's Google Drive integration includes an 'Updated File in Folder' trigger that polls the watched folder at your plan's polling interval. When Zapier detects a changed file, it fires the zap. This works without any coding and supports routing the PDF to other tools in the same workflow.

If a document is edited frequently, event-driven triggers can fire many times in a short period. This wastes API quota and creates many redundant PDF versions. A common solution is to record the last time a conversion ran for each document and skip a new conversion if the last one happened within the past N minutes. This debounce pattern is straightforward to implement in Apps Script using PropertiesService.