Sometimes users can input the strangest things, luckily there's some simple built in validation tools available for every form field.
Making it a requirement
To make a field required, simply check the "Required" checkbox in the Add/Edit Field dialog box. Once required the form will not be able to be submitted without content in the field.
Adding additional validation to a field
There are several additional kinds of validation that are built into the forms library and are easily added to any field. Simply add the appropriate class to the field in the add/edit field dialog box and users will not be able to submit forms until they have valid content in the field. NOTE: You can have a field required as well as validated in another fashion (e.g. set a field to be required and having an email address).
Requires a field to be a valid email. This is likely the one you'll use the most and should be added to every email input you have, especially if it's the email field being used to send the confirmation email.
Requires a field to be a valid url.
Date and DateISO
Requires a field to be a valid date. DateISO requires dates to be formatted according to the international date standards.
Requires the field to be a decimal number.
Requires the field to use digits only.
Requires the field to be a credit card number.
If you require additional or custom validations, let us know, we can generally add validations to meet any of your form needs