Script to add Google Sheets MultiSelect fields from dropdown selections.
gsheets-multiselect - Google Sheets MultiSelect - @ControlAltPete 2023
Allow cells with data-validation to have multi-select. The cell should have data validation from a range and the cell immediately above that validation range must contain: MultiSelect:ShowInCell or MultiSelect:ShowRight or MultiSelect:ShowBelow
The default item separator is "value1, value2" but this can be changed by adding ",Sep=" to the MultiSelect cell, eg: MultiSelect:ShowInCell,Sep=| If the Sep has a comma or spaces you need quotes, eg: MultiSelect:ShowInCell,Sep=" , "
The special values '' (blank) 'None' and 'All' will replace all previously selected values.
Google Sheets will show a warning triangle when multiple items are selected, This warning shows for ShowInCell but not for ShowRight or ShowBelow. To hide this warning, add ",HideWarning" to the MultiSelect cell, eg: "MultiSelect:ShowInCell,HideWarning" but be aware this will add a new dropdown option with all the current selected items ie: the dropdown: 'Apple' 'Banana' 'Cherry' can become 'Apple' 'Banana' 'Cherry' 'Apple,Banana' A limitation of HideWarning is it can only hide the warning for ONE input cell If multiple input cells share the same data validation range and have different multi-select choices only one of them will have the warning triangle hidden at a time.
I have a demo sheet you can copy and play with here: https://docs.google.com/spreadsheets/d/1Uu2p6xP_oG3iE3XffpXBxAYsPyRFdvO8aDVaWSOjDMM/edit#gid=0
Installation: Google Sheet, click on Extensions > Apps Script, paste this. You may need to allow some permissions when it runs.
