This guide shows how to create a validation rule that ensures: The first 4 characters are uppercase letters (A–Z) and the last 4 characters are digits (0–9)
Scenario
You have a field called "barcode" in your form, and you want to match it against this structure:
AAAA0000
↑ ↑
| └── Four digits
└────── Four capital letters
For example, the following inputs should be considered valid:
Input | Valid? |
---|---|
ABCD0312 |
✅ Yes |
abcD0312 |
❌ No |
ABCD123 |
❌ No |
A1C20312 |
❌ No |
ABCD03123 |
❌ No |
Rule Configuration
Step 1 - In the barcode field, navigate to the 'Field Validation Rules' tab
Step 2 - "Mark form as Valid without message, when"
data["Barcode"] =~ "^[A-Z]{4}[0-9]{4}$"
This regex means:
-
^[A-Z]{4}
→ Starts with 4 capital letters -
[0-9]{4}$
→ Ends with 4 digits -
^...$
→ Anchors it to exactly 8 characters, no more, no less
Step 3 - Add a new validation rule with the '+' icon
Step 4 - Click the 'valid' button to change to 'Invalid' and select a colour
Step 5 - "Otherwise, mark form as Invalid without message, when"1
1==1
This always evaluates as true, meaning any unmatched input is invalid by default.