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google-apps-scriptgmail-apigoogle-tasks-api

How to trigger Google Script when a Google Task is marked "completed"

Google Apps Script allows scripts to be triggered by a variety of events; see here.

I'd like to update the tag on an email (in Gmail) when the user marks a task completed (in Google Tasks) but there doesn't seem to be a trigger for this.

However, Zapier is able to trigger on these events somehow: supported triggers

So it seems like this trigger must exist.

Is there a way to do this other than using Zapier?

Unfortunately Zapier (in addition to costing money) only allows you to add tags to Gmail messages, not remove them -- so one can't (for instance) change a message tag from [uncompleted-task] to [completed-task].

Solution

  • As of this writing (2018-05-15), Google Apps Script does not support a trigger to track a task's status.

    I suspect that Zapier is polling the status of the task via the Task API; ie. periodically checking the status property of the task and firing an event once the status changes to complete.

    You can do the same (with time-based triggers) using the Task API as an Advanced Service in GAS: