Forums

Articles
Create
cancel
Showing results for 
Search instead for 
Did you mean: 

I'm trying to find an automated solution to increase the value of a number on a card

PJRanson
Contributor
November 6, 2025

I'm testing an idea.

I want to be able to automatically update a number on a card that is created from a checklist item.

In this case the number in question is an invoice reference number - I've created a sample reference card with my current invoice number "00145" as the card title.

I have a checklist item "Prepare Invoice # (xxxxx)" that when converted to a card, triggers an action that finds the sample reference and applies it to the newly created card. 

The idea being that once I've checked off the newly created "prepare invoice #00145" card, then it finds the reference card "invoice #00145" and then renames it to "invoice #00146"

I can figure out the logic for all but the last bit.

Is there an option that allows for incrementing a value on card by n+1?

 

2 answers

1 vote
Mike - Dreamsuite Consulting
Community Champion
November 6, 2025

HI @PJRanson 

 

You could use a custom field to help you.

Call your custom field Invoice #.

You use this numeric field to create your invoice number.  When this field is completed, it sets the name of the card:

Automation 1

When custom field "Invoice #" is set, set the card name to "{customfieldname}{customfieldvalue}"

 

Automation 2

When the "Prepare Invoice #{*}" is checked, find the card named "Invoice  #{wildcard1} and increase the number of custom field "Invoice #" by 1  

 

Automation 2 will increment the Invoice # custom field and in turn trigger Automation 1 to update the name

PJRanson
Contributor
November 6, 2025

Yeah, thanks @Mike - Dreamsuite Consulting That's pretty much what I've setup.

That second trigger doesn't necessarily work with how I actually prep my invoices in practice.

The trello logic works, but that assumes that I actually prep invoices in the same order. 

Which is more about my day to day working practices.

It's hard to explain. Multiple lists, multiple clients, multiple invoices being produced, with various jobs overlapping one another - one invoice might be prepped (but incomplete), and another invoice after that one can be prepped and sent.

The whole point was just to keep tabs on the invoicing number (and eventually estimate numbers too) so it tallies with my accounting software - I may jump down the zapier/webhook rabbit hole at some point to link it all up. 

I dunno... Maybe 

Point being, the trigger for changing the invoice reference number isn't completing the action to prepare it, it's the very action of applying that number to the new card that should increment the custom value by 1.

Like I said, maybe I need to change my working method to fit. 

 

 

 

Mike - Dreamsuite Consulting
Community Champion
November 7, 2025

Hi @PJRanson 

Have you considered using the {cardnumber} variable for this?  

Each Trello card has a Card number, is it the number based on when it was created. It is unique and should represent an incrementing structure you want. The only exception for this being unique is if you move cards from 1 board to another...

For sure, using an external tool like Zapier will benefit you. My personal choice is Make (make.com) 

Both Zapier and Make are excellent tools for more advanced automation, when it comes to Trello, Make definitely opens up greater potential than Zapier, especially if you can get your head around the Trello API.

 

Top tip, you can use Trello automation to Trigger a webhook. I use this A LOT when I am building solutions for people with Trello. 

 

Sales.png 

It sounds like you may be trying to shoehorn a solution into something where it doesn't quite fit and that may result in a lot of wasted hours for an outcome you're not satisfied with (believe me, I've been there more than most)

I would suggest taking a bit of time to really get to grips with what you ultimately want to achieve and why, draw out the steps need to achieve it then work out the best option to deal with how.

Like PJRanson likes this
PJRanson
Contributor
November 7, 2025

Ah... just done it... I added the function to increment the custom value by +1 as part of the rename card action. 

Nice!

PJRanson
Contributor
November 7, 2025

I'll dive into webhooks and those other options at some point I'm sure... I'll apply this solution to my main boards and see if that works in practice first though.

Thanks for the input.. ;)

Mike - Dreamsuite Consulting
Community Champion
November 7, 2025

Glad you got there and its nice to be able to nerd out about automations with someone. If you have any other questions, don't hesitate to ask on here as I'll most likely see it.

Feel free to subscribe to https://ace.atlassian.com/trello-trailblazers/ 

This is an Atlassian Community Events group specifically for Trello, we hold events and create content.  

Lastly, I have created a couple of articles with more advanced automations, worth taking a look if you're interested:

https://community.atlassian.com/forums/forums/searchpage/tab/message?include_blogs=true&q=mikes-trello-tips&allow_punctuation=false&advanced=false 

There are some examples of using API calls in Trello automation to enhance its capability, as well as the Trello automation secret weapon - Regex!

 

Check it out 

Like PJRanson likes this
PJRanson
Contributor
November 7, 2025

@Mike - Dreamsuite Consulting I see your London based - (I'm down in Brighton FWIW) - just our of interest - do you happen to know if Freeagent has potential for integrating with make? That might be a useful avenue to explore. I'm not a coder as such, but do have a technical background (in game dev), so not averse to simple scripting and picking my way through APIs/Proprietary systems.

Mike - Dreamsuite Consulting
Community Champion
November 7, 2025

Hi @PJRanson 

It's even nicer to chat to a fellow UK Trello users. I know they exist but I battle to find Trello users in the UK.  I'm actually even closer than you think, I'm just down the road, half way between Portsmouth and Chichester (although, I'm currently sending this from Indonesia 😄)

A quick look and Freeagent has a very comprehensive set of Make modules:

Screenshot 2025-11-07 16.44.48.png

I think that it would be really cool to integrate FreeAgent and Trello and will certainly allow you to remove a number of your Trello manual and automated steps.

 

Feel free to have a hunt for me on LinkedIn, I'm always happy to chat to Trello fans in the UK 🙂

Like PJRanson likes this
PJRanson
Contributor
November 7, 2025

interesting... #strokeshisbeard ;)

 

0 votes
Sunny Ape
Rising Star
Rising Star
Rising Stars are recognized for providing high-quality answers to other users. Rising Stars receive a certificate of achievement and are on the path to becoming Community Leaders.
November 6, 2025

Hello @PJRanson 

Trello's built-in automation cannot perform mathematical operations, so it can't take a number and increment it by another number or value, as your use case infers.

Mike - Dreamsuite Consulting
Community Champion
November 6, 2025

Hi @Sunny Ape 

I appreciate your response to this but you are entirely wrong. Trello's automation can indeed perform arithmetical operations. I can also increment/decrement numeric fields.

https://support.atlassian.com/trello/docs/working-with-custom-fields/#Custom-Field-arithmetic 

Like # people like this
PJRanson
Contributor
November 6, 2025

@Sunny Ape 

It cannot in the way I had anticipated, but there is a way I've figured out how to solve my original problem...

Using Custom fields it is possible to define a numeric value and using a trigger to increment it by whatever amount you want.

I'm still experimenting, but... 

  • I have ap template checklist item "create invoice" that when a date is applied in the checklist, creates a new linked card in the list
  • That new card is then renamed to include the invoice number (taken from the a reference card elsewhere on another board)
  • This triggers the custom numeric field (on the reference card) to increase by 1
  • Which then triggers the reference card to be renamed using the new numeric custom field value 

So, it's definitely possible. Albeit requiring multiple automations and triggers. 

The final trigger to rename the reference card I'm still undecided if it's going to work in practice.

But, as proof of concept (using the stock variables/automations) it can work.

Like # people like this
PJRanson
Contributor
November 6, 2025

@Mike - Dreamsuite Consulting 

Thanks Mike, that's reassuring to know there are additional arithmetical functions - I'm muddling my way through to a solution. 

I love fiddling around with these settings. It's only been a couple of weeks since I did a deep dive into the cascade functions but I'm glad I ventured forth as it's transformed my workflow.

I used to have checklist items that had reminders to change this setting, or apply that label etc... And just sitting back and thinking about how I can use the butler/cascade interface has streamlined a great deal of actions. 

Linked checklist items was the gateway - once I'd figured that out the rest has been a real journey of discovery. 

Sunny Ape
Rising Star
Rising Star
Rising Stars are recognized for providing high-quality answers to other users. Rising Stars receive a certificate of achievement and are on the path to becoming Community Leaders.
November 7, 2025

Thanks @Mike - Dreamsuite Consulting 

You're completely correct. I was just thinking about trying to do the arithmetic directly on numerical part of the text field's value, and didn't even remotely consider using an intermediate numerical custom field.

Suggest an answer

Log in or Sign up to answer
DEPLOYMENT TYPE
CLOUD
PRODUCT PLAN
FREE
TAGS
AUG Leaders

Atlassian Community Events