Field validation

Validate text patterns using regular expressions or allowing only numerical input

Regular Expressions (Regex) are sequences of characters that define a search pattern in text. You can use them to validate text based on complex criteria and match common text patterns like phone numbers and IP addresses. Regular expressions are both flexible and powerful, capable of matching virtually any text-based pattern you might want to include in a form.

If you don’t want to check for specific patterns but want to narrow down inputs to numbers, you can enforce this validation by allowing only numbers in the input field. This will narrow down possible errors when providing postcodes, identifiers, or bank account numbers.

Validation of short text fields

When you create your form, you can decide what type of field input is allowed. To help you eliminate possible input errors, you can decide to enable field validation for the short text fields.

Based on the type of input you expect, you can also create a customized message for users to see when they provide incorrect data.

For limitations in the supported regular expressions, see Syntax (external page). You can use this external page to test if your expression is correct.

Common regex examples

Input	Expression	Validation	Input match	Example of validation message
IBAN	^[A-Z]{2}\d{2}[A-Z0-9]{11,30}$	Checks for IBAN structure (no spaces, no lowercase letters, between 15 and 34 characters in total)	DE89370400440532013000DDE89370400440532013000	The IBAN has an incorrect format
German IBAN	^DE\d{2}\d{8}\d{10}$	Ensures the IBAN follows the structure for German accounts and is 22 characters long	DE89370400440532013000FR89370400440532013000	Ensure this is a German IBAN
Supplier identifier	^[A-Z]{2}\d{6}$	Ensures that the identifier follows the pattern of 2 uppercase letters followed by exactly 6 digits	NL336789NL33557700N	This is not a correct identifier
Postcode	^\d{5}$	Checks for 5 digits	85774874	Ensure the code has five digits
Value greater than 0.00	^([1-9]\d*(\.\d{1,2})?|0\.[1-9]\d?)$	Check whether the value is greater than 0.00	2.540.00	Enter a value greater than 0.00
Positive value or 0	^(0|[1-9]\d*)(\.\d{1,2})?$	Check whether a value is a positive number or 0. Allow decimals.	0.12-12	Enter a positive value or 0
Email addresses with a specific domain	^[a-zA-Z0-9._%+-]+@mycompany\.com$	Validates email addresses that end with “@mycompany.com”	[e-mail]
Price format with a comma for decimal and dot for thousands	^[1-9]\d{0,2}(\.\d{3})*(,\d{2})?$	Validates European-style formatted numbers with optional thousands separators and exactly two decimal places	1.234,56 or 1.234.567,89123456,78	Enter the price separating thousands with a point

Note that the operation doesn’t support Pearl syntax in the editor. This means that look-around expressions such as: (?=...), (?!...), (?<=...), or (?<!...) are not supported. This refers to all positive and negative lookahead expressions and positive and negative lookbehind expressions.