Conditional Logic and Validation Rules

Overview

Two features keep your forms short and your data clean: conditional logic (show a field only when it's relevant) and validation (reject answers that don't meet your rules). Both are active in StretchForms and configured on the form.

Conditional logic

Conditional logic lets a form react to what a respondent enters. A field or an entire step appears only when a condition on an earlier answer is met.

Common patterns

• Branch on a choice. If How can we help? = Request a quote, show the budget and timeline fields; otherwise hide them.
• Follow-up questions. If Are you an existing customer? = Yes, show Account number.
• Skip irrelevant steps. Reveal the Shipping step only when Delivery method = Ship to me.

Set up a conditional field

1. Add the field you want to show or hide.
2. Open its logic settings.
3. Choose the controlling field (an earlier question), the operator (equals, is not empty, and so on), and the value that triggers visibility.
4. Save and test by entering answers that both meet and fail the condition.

When you use conditional logic with multi-step forms, StretchForms remembers which fields were visible for each respondent as part of their partial save — so a resumed form shows exactly the right questions.

Validation rules

Validation stops bad data before it's ever stored. Beyond the built-in checks that come with field types (email format, numeric input, date picker), you can add rules that enforce your requirements.

Typical validation rules

• Required — the respondent must answer.
• Format / pattern — the answer must match a shape (for example a postal code).
• Length — minimum and maximum characters.
• Range — a number or date must fall between bounds (for example, budget ≥ 1000, date not in the past).

Add validation

1. Open a field and go to its validation settings.
2. Turn on the rules you need and set their parameters.
3. Optionally write a custom message so respondents know how to fix an invalid entry.
4. Save and test with both valid and invalid inputs.

Example

An events team builds an RSVP form:

• Attending? — dropdown: Yes / No.
• Number of guests — number, shown only if Attending? = Yes, validated to be between 1 and 6.
• Dietary notes — long text, shown only if guests ≥ 1.
• Reason — long text, shown only if Attending? = No.

Every respondent sees a short, relevant form, and the guest count is always a sensible number.

Tips

• Hide, don't ask twice. Conditional logic keeps forms feeling short even when they cover many cases.
• Validate at the source. It's far cheaper to reject a bad email on the form than to chase it later.
• Write helpful error messages. "Enter a number between 1 and 6" beats a generic "Invalid".
• Test every branch. Walk through each path a respondent could take before publishing.

Troubleshooting

A conditional field never appears. Re-check the controlling field, operator, and trigger value — the condition may never evaluate true. Confirm the controlling field comes before the conditional one.

Validation is blocking valid answers. Loosen an over-strict pattern or range, and confirm the field type matches the data (don't put a numeric range on a text field).

Resumed forms show the wrong fields. Ensure conditional fields are configured on the form itself; StretchForms stores the visible-field set with each partial save, so the logic must live on the form definition.

FAQ

Can a whole step be conditional? Yes — reveal or skip an entire step based on an earlier answer.

Do hidden fields still collect data? No. A field that's hidden by logic isn't shown and isn't required, so respondents aren't blocked by questions that don't apply to them.