Zapier trigger on update

Question

I want to write an update trigger for my Zapier app as Trello has "Card Updated" - "Triggers when a Card is updated in Trello.". However, I can't find any good examples, any idea how to do that? Thanks

Answer 1

David here, from the Zapier Platform team.

To understand updates, you must first understand the way Zapier does deduplication. Namely, we keep a list of all the ids we've seen over the lifetime of the zap and only trigger once for each. This makes it easy to trigger on a new card via polling.

The easiest way to do updates is via REST hooks. When there's a change on your end, you POST to us and let us know. The best version of this enumerates which field(s) changes and their old and new values.

While it's technically possible to do this via polling as well, the UX is really tough. Instead of using the id, you'd need to make a new id out of the id and whatever you're interested in tracking updates for. If that was the "assignee" field, you could edit each card in your poll result to have the id id:assignee. That way, when a card was reassigned from Alice to Bob, the dedup system would see a new id (5:alice and 5:bob, respectively). It's hard to extrapolate that out to all fields though, and it's next to impossible to tell what fields changed via a poll. There are some other creative ways to handle it building the id, but the UX to the end user is limited to knowing that a card probably updated (but not knowing in what way).

Hope this helps. ​Let me know if you've got any other questions!