Use Validation Rules

Prevent form submission until specific conditions are met - like checking that a value is in range, an email matches a domain, or a required acknowledgment is checked.

What are Validation Rules?

A Validation Rule is an expression attached to a form field that must evaluate to true before the form can be submitted. If the rule evaluates to false, the submitter sees an error message and cannot proceed until the field meets the criteria.

Validation Rules go beyond the basic Required toggle. While Required simply checks that a field isn't blank, a Validation Rule can enforce specific formats, ranges, cross-field comparisons, and business logic.

Common uses include:

• Ensuring an email address belongs to your organization's domain
• Verifying a dollar amount matches an expected total
• Requiring that a True/False acknowledgment is checked
• Checking that a date falls within an acceptable range
• Confirming that table row totals add up correctly

Add a Validation Rule to a field

1. In the Form Builder, select the component you want to validate.
2. In the Properties panel on the right, click the Validation Rule icon.
3. Write your expression, or use click Switch to Code and use Droplet AI to generate one from plain language.
4. Add a custom error message that tells the submitter what needs to be corrected.
5. Click Apply Rule, then save your form.

Write a Validation Rule expression

A Validation Rule expression must return true when the field value is valid, and false when it is not. You can reference other fields by their component ID, just like in formulas.

Common examples

Email must match a domain

value.endsWith('@yourdistrict.org')

Returns true only if the entered email ends with your domain.

Number must be within a range

value >= 1 && value <= 100

Returns true only if the value is between 1 and 100.

True/False must be checked

value === true

Returns true only when the checkbox is checked. Use this to require acknowledgment on a True/False component, which does not have a built-in Required toggle.

Field must match another field

value === confirmEmail

Returns true only if this field's value matches the confirmEmail field. Useful for "confirm your email" patterns.

Table column totals must match an expected value

sum(amount) === fromCurrency(totalContractValue)

Validates that the sum of an amount column matches a total entered elsewhere on the form.

Condition-based Validation Rules

Instead of writing a formula expression, you can build a Validation Rule using a visual condition builder. This is useful when you want to validate based on another field's value without writing code.

Each condition checks:

• A field to evaluate (identified by its component ID)
• A comparator - such as equals, not equals, contains, or includes
• A value to compare against

You can combine multiple conditions. The field is valid when all conditions are met.

Make validation conditional

Sometimes a Validation Rule should only apply under certain circumstances. For example, you might require a driving amount field only when the mileage type is "Personal Vehicle."

To make validation conditional, use a ternary operator that returns true (always valid) when the condition doesn't apply:

mileageType === 'Personal Vehicle' ? value > 0 : true

This reads as: "If mileage type is Personal Vehicle, the value must be greater than 0. Otherwise, any value is valid."

You can also use isOptional() in your validation expression to mark a field as not required under certain conditions:

equals(nextAction, 'Approve') ? value : isOptional()

Validate fields inside tables

Validation Rules work inside table columns too. When writing a rule for a table column, use getCell() to reference other columns in the same row:

getCell(drivingAmount) ? getCell(value) : true

This validates that the current column has a value only when the driving amount column in the same row is filled in.

Frequently asked questions