How can I assign a new sequential number to a custom field based on a previous card's number?

[Katey Sackett]

I am working on a board that I would like to automate a number assignment for certain cards. This could be a button trigger or label. 

The full issue is a weird numeric naming convention "YY-###" with YY being the assigned fiscal year and the ### starting at 0 at the beginning of the year and increasing by one with each of these particular cards when triggered. Not all cards will need this number but the number must remain sequential when added (refers to another system in operation). 

We've discussed a way to remove the YY from the problem, including it as printed information elsewhere, but not the ###. 

My understanding is that I could have the system read the last number in that custom field and increase it by one, but how would I set that up to call the last available custom field number, ignoring the blanks?

If someone has an alternative solution that would incorporate that "YY-" naming convention that would be great too. The goal would be to have the number in a field that could then be sent to a linked card on another board and printed elsewhere, like the title of the card, which I can do, once I can get the custom field number assigned.

I am trying to avoid another power up that creates a separate section on the card because I want to keep the cards clean for the person that will be using the board. If there is a powerup that might solve this issue but won't clutter up the card, I would be open to exploring that option. 

[Beverley]

Hi Katey - welcome to the community!

You could create an automation rule or a card button to automate an increase to the custom field number.

How you setup your automation rule would depend on what criteria the card needs to meet in order for the custom field number to increase. For example, would it be a specific label that needs to be added, or when a card is added to a certain list or if a card is added with a certain name?

We’ll use a custom field called “Number” in the following example.

An example of an automation rule could be:

when the green label is added to a card, increase the number in custom field “Number" by 1.

Or a card button example could be:

increase the number in custom field “Number" by 1.

If you’d like to create a linked card or update the title of the card after the custom field is updated, then you could create another automation to reference the custom field (https://support.atlassian.com/trello/docs/working-with-custom-fields/)

For example, if you’d like to copy the card, then you could create a card button such as:

copy the card to the top of list “List name", rename the card to "24 - {{%Number}}", and link the cards together

We have more information about creating and managing automations: https://support.atlassian.com/trello/docs/creating-and-managing-butler-commands/

I hope that helps!