How can I prevent duplicate submissions in my system by checking against existing values in a database or data structure?

Prevent Duplicate or Invalid Values with Custom Validation

Want to ensure users don’t submit a value that already exists in your form’s database? Follow these steps to set up custom validation:

✅ Step-by-Step Guide

1. Log in to your account.
2. Go to the Forms section.
3. Select the form you want to edit.
4. Find the field you want to validate and click the ⚙️ settings icon.
5. On the right panel, open the Custom Validation section.
6. Select the input field under "Operator," then click Add condition.
7. Choose either:

• "Exists in submissions" – to check if the value already exists (e.g., to block duplicates), or
• "Does not exist in submissions" – to allow only new/unique values.

8. Add a custom error message that will display if the condition is not met.

9. Click Publish to save your changes.

Example

Use this to prevent duplicate email addresses, usernames, or IDs from being submitted more than once.

📝 Supported Fields for Custom Validation

You can apply custom validation to the following field types:

• Title
• Email
• URL
• Phone number
• Rich Text
• Number
• Select
• Multi Select
• Status
• Date
• User
• Relation

⚠️ Note: Some complex fields (like Relation or User) may require additional setup or reference to linked databases.

Updated on: 06/02/2026