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Any valid regular expression could be used here. Some examples you can see below.
| Warning |
|---|
Validations run on form submit |
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Since version 1.4.17 you can use the reserved word [unique] in order to check for field's value uniqueness. See examples below.
| Validation | Regular expression |
|---|---|
| Value is empty | ^\s*$ |
Value NOT matching something (Allow everything, but 'something'. Useful when you would like to apply validation on dropdown fields) | ^(?!something).*$ |
| Value is not empty | ^(?=\s*\S).*$ |
| Value is alphanumeric | ^[a-zA-Z0-9]*$ |
| Value contains only letters | ^[a-zA-Z]*$ |
| Value length (1-20 chars) | ^.{1,20}$ |
| Only numbers | ^[0-9,;]+$ |
| Checks if the field's value is unique within the dataset | [unique] |
| Checks if the field's value is unique within the dataset and ensures it's length (1-20 chars) | ^.{1,20}$[unique] |
| Allow only PDF files (files with "pdf" file extension) | |
| Starts with upper case letter followed by 9 numbers | [A-Z]{1}\d{9} |
| Starts with 2 letters, upper or lower case and followed by 6 numbers | [a-zA-Z]{2}\d{6} |