Help with ConfiForms Booking Validation Rule

[Enrico Mancuso]

Hello Everybody, 

I’m currently implementing a ConfiForms-based booking system using a datetimeinterval field (datum) and a checkbox_group field (Geraete) to allow users to book one or more devices for a selected time period.

What I’ve achieved so far:
I successfully implemented the validation logic described in the official documentation to prevent overlapping bookings.

---

datum.startDate: <= [entry.datum.endDate] AND
datum.endDate: >= [entry.datum.startDate] AND
!id:[entry.id]

---

This correctly prevents overlapping bookings across all records.

My problem:
This rule currently blocks any overlapping booking, regardless of which device is selected. But I want the validation to apply only if the same device is already booked during the selected time range.

For example:

• If Waffle Iron is already booked from 12:00 to 14:00, users should not be able to book Waffle Iron again in that time.

• But they should still be able to book Grill or Sound System during the same time.

My goal:
To build a validation rule that only checks for time overlap when at least one selected device in the new record matches a device already booked in the same time interval.

Thanks a Lot

Enrico

[Alex Medved _ConfiForms_]

This will validate the whole booking, no matter what you have selected in the "checkbox group field"...

I would strongly suggest to switch to a dropdown to be able to select just one item for booking. This will make the booking logic a lot simpler than trying to figure out how to make this work for the multi-selects

Unless of course you have a predictable and low number of items in the checkbox group and you can add the very same validation rule, but that includes a condition to check the specific item in the checkbox group (so separate rule for each items in the checkbox group)