====== RequiredRule ======

Input validation rule that tests for a field.  Mandates that the field exists; is required.

An "I agree to these terms and conditions" checkbox would be a good example candidate for a [[RequiredRule]].

===== Example =====

<code php>
$form->addRule (new RequiredRule ('fieldName'));
</code>

This example checks that the field "fieldName" exists.

===== Additional Information =====

  * [[wact:api:validation:rule:catalog|Validation Rules]]
  * WACT [[wact:Form Validation]]