@M_Hermi hey that’s a good question and it can be accomplished in Coda. There is a way to configure ‘Lookup Settings’ when you set a column to be a lookup type. Click into the column settings, then scroll to Item Settings. Then add a filter, and then a formula.
Now think of it this way - your formula is going to be looking at the display column from the table that you’ve selected as the lookup. So you need to limit the that list to not include any item that has already been selected. So how do you determine which ones have been selected?
In this example, we have the States table where each state can have a govenor selected. We want to get the list of selected govenors, and we can do that by getting the list States.Govenor.
Now to tie this back to the lookup filter, you use the currentvalue variable to tell the filter to check each item, and we want to see if the currentvalue is in() that list. This can be written as CurrentValue.In(States.governor).
OK but you don’t want it to show if its already been selected. We now reverse the logic by adding not() to the formula:
not(CurrentValue.In(States.governor))
I’ve created an example and video to show you. Good luck!
