3 Dropdowns - remove 'options' dynamically


I have 3 dropdowns for users to indicate their 1st, 2nd and 3rd preference - lets say its school subjects for this example.

Each dropdown loads the same option set, with 10 options.

On selection of a subject in the 1st dropdown, say Maths, that subject should be removed from the 2nd and 3rd dropdowns. Selecting English in the 2nd dropdown should remove it from the 3rd dropdown.

There is a :minus item function, however, it only allows 1 value. I tried to create custom state (list) to store the users selections, so that I could use :minus list, but I cant see a way to trigger a workflow when a user selects an option from a dropdown…

Is there an elegant way to achieve what I am trying to? Basically I want all subject preferences to be unique… Alternatively, I could just validate the selections when the user submits the form, and return an error e.g. “You cannot select a subject more than once”

Hi there, @thethinklab.au… the :minus item operator should work just fine. The 2nd dropdown would be the full list minus the 1st dropdown’s value. The 3rd dropdown would be the full list minus the 1st and 2nd dropdowns’ values. and you can accomplish that by stringing two :minus item operators together.

Hope this helps.


Hey, Mike is right, the minus item on the choice source of dropdown should work fine… you don’t need a workflow. Also use a dynamic choice style.

Thanks - I had tried but it wasn’t evaluating - tried again and it’s working… :slight_smile:

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