Nintex Form - Check Calendar Double Booking

Hi ‌

You can use the Lookup function in the validation formula. Ensure to use Named Controls (NOT Item Properties) for the filter in the lookup. Í haven't tested it, so I can't assure you will be successful. You might need to add a calculated field (e.g. = <StartDateTime>-<EndDateTime>) to your Calendar list that is used for the Lookup filter......

Hi John,‌

The syntax for the lookup formula function is:

lookup("list title","column to filter on", value to filter on, "output column". [multiple values-boolean] , [value data type])

Which takes only 1 filter value. If that's sufficient e.g. Start Time can't be the same, and your start time control is Named "Start", then your lookup might look like:

lookup("Calendar", "Start Time", Start, "ID", true)

If it's EmptyOrNul, then no other entries are starting. Combine this with a lookup for End Time. Alternatively you could include a calculated Calendar column (e.g. EventWindow concatenating start and end time and use:

lookup("Calendar", "Event Window", Start-End, "ID", true)

Again, the above I've not yet tried myself, but you should be able to get this to work.

A completely different approach would be to use JavaScript to do the check of double bookings.