Event Planning on Trello - setting card/checklist due dates based on dynamic event date
Asked by Casey Royer:

I'm using Trello to plan lots of events for my business (and personal life). I need a way to set an event date (or anchor date?), and then have all the cards in each list set to a due date based on the event date (ex: list that is due 12 months before the event, a list that is due 3 months before, 1 week before, etc.). I'd like to be able to change the event date and have all the cards' due dates updated automatically. Can this be done?

I've already created a rule for each list to set cards due dates when they are added to specific lists, but this doesn't solve my problem of needing to be able to change the event date and have all due dates automatically update. I'd have to go in and update the rule for each list, then move cards out of the list and back into the list again.

Thanks for any ideas/help you can offer!


Answers:
author: Hannah Humbert - Simpla Workflows
body: [@Casey Royer](/t5/user/viewprofilepage/user-id/5426604) welcome to the community ? check out this video I created which is sort of close to what you're looking to achieve:  


author: Lucas Pessoa
body: Hey [@Casey Royer](/t5/user/viewprofilepage/user-id/5426604) , If you're open to perhaps migrating to a different platform, I'd love to learn more about what you're trying to accomplish and recommend different solutions


author: Maria
body: Hi [@Casey Royer](/t5/user/viewprofilepage/user-id/5426604)   

It's Mary from [Planyway: event calendar and timeline for Trello](https://planyway.com/trello?utm_source=atlassiancommunity&utm_medium=referral&utm_campaign=atlassianquestions)

Automating the update of due dates in Trello based on a central "event date" requires a bit of creativity, as Trello's native functionality may not support such dynamic due date adjustments directly. However, you can achieve this functionality through a combination of Trello's Power-Ups, third-party automation tools like Zapier or Butler, and perhaps some custom scripting. Here's a strategy to consider:

### Using Automation (Butler) in Trello {#toc-hId-2112353803}

1. **Central Card for Event Date**: Create a central card in a dedicated list that holds the event date. This card will act as your "anchor" for all other due dates.

2. **Butler Automation**: Use Butler to create commands that trigger on changes to this central card. Unfortunately, Butler doesn't directly support triggering actions based on changes to a specific card's due date. Instead, you can use a workaround by manually triggering a command whenever you update the event date. For example, you could add a label to the card as a signal to run your commands and then remove it as part of the command sequence.

3. **Updating Due Dates**: Create a command in Butler for each list or group of tasks that should have their due dates set relative to the event date. This might involve:

   * Triggering on the event date card's label change.
   * Calculating the difference between the new event date and the original due dates for each list.
   * Adjusting each card's due date in the specified lists by the calculated difference.

This approach requires manual intervention to trigger the updates (e.g., changing a label on the event date card) and some careful setup in Butler to ensure the due dates are calculated and adjusted correctly.

### Using External Automation Tools (e.g., Zapier) {#toc-hId-304899340}

1. **Zapier Automation**: Set up Zaps that:

   * Trigger when the event date in the calendar changes.
   * Search for cards in specific lists in Trello.
   * Calculate the new due dates based on the updated event date.
   * Update the due dates on the cards in Trello accordingly.

This method may offer more flexibility and automation but requires a Zapier account (potentially with a premium plan, depending on the complexity and volume of your automation).

### Custom Scripting with Trello API {#toc-hId--1502555123}

If you have programming skills or access to developer resources, you can create a custom script using the Trello API to:

* Monitor changes to the event date card.
* Automatically calculate and update due dates for all relevant cards.

This approach offers the most control and automation but requires development time and maintenance.


author: milynnus
body: [@Casey Royer](/t5/user/viewprofilepage/user-id/5426604)

In Trello, if you need to relate a card to another, you will need to connect them via cardlinks. Typically this will be in a checklist or just a cardlink attachment. For cards in a list, you will need to gather them together via automation into a checklist and iterate through each card.

However, the above implementation does not allow you to set due dates if the criteria cannot be implemented via an action in Trello automation especially when the time intervals between event or from an schedule date cannot be easily determined.

The way one of my customer had done was to set a list of events (Cards) on Google Sheet. Use Google Sheet to calculate the due dates and create the cards with due dates set. This, however, does handle the case of a change in event date.

For retrospective change of due dates, it will involve some custom code. In an earlier piece of work, I am able to change checklist item due dates when there is a change in the card due dates. This design pattern can be used to handle a change of event date and retrospective adjust the other active card due dates.

Obviously, the above requires some development.