How to Use Custom Validation

Custom validation allows you to define specific rules for input fields using regular expressions (regex).

Note: This option is currently available only for the field types: ‘Text’ and ‘Number’

Basic Regex Patterns

1. Letters only: ^[A-Za-z]+$

• Matches any string containing only letters (A-Z or a-z).

2. Numbers only: ^\d+$

• Matches any string containing only digits.

3. Letters and numbers: ^[A-Za-z0-9]+$

• Matches any string containing letters and/or numbers.

4. Email address: ^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+.[a-zA-Z]{2,}$

• Matches most common email address formats.

5. Phone number: ^+?[\d\s-]{7,}$

• Matches phone numbers with optional ‘+’ at the start, and allows digits, spaces, and hyphens.

6. UK Postcode: ^[a-zA-Z]2\d[a-zA-Z\d]?\s*\d[a-zA-Z]2$

Quantifiers

• {n}: Exactly n times
• {n,}: n or more times
• {n,m}: Between n and m times
• *: 0 or more times
• +: 1 or more times
• ?: 0 or 1 time

Examples

1. 3-10 letters: ^[A-Za-z]10$

• Matches strings with 3 to 10 letters.

2. US Zip Code: ^\d5(-\d4)?$

• Matches 5-digit zip codes and optional 4-digit extensions.

3. Date (YYYY-MM-DD): ^\d4-\d2-\d2$

• Matches dates in the format YYYY-MM-DD.

Tips

1. Use ^ to match the start of the string and $ to match the end.
2. Test your regex thoroughly with various inputs.
3. Balance strictness with usability to avoid frustrating users.

For more advanced patterns and detailed explanations, visit RegExr.