Ensure unique selections - Each item can only be chosen once

English Forum Questions
1

I have an order form and I want users to add one product only one time so all items added to order are unique.

I tried creating
one to one (has one)
one to one (belongs to)

but still i can select same item twice

image

2

@support @shleyZ any update?

3

Three business tables
Order
Order detail
Product

Order (one-to-many) Order detail
Order detail (many-to-one) Product

Using the pre-action event workflow:

Pasted image 20251122114327
Pasted image 202511221143272445×714 40.8 KB

Workflow for pre-operation events When submitting data for a new order, check if there are duplicate products in the order details data
Workflow for pre-operation events When submitting data for a new order, check if there are duplicate products in the order details data1920×1994 248 KB