Give user empty form on form validation error

Question

I'm using braintree.js with a custom form. For those not familiar, braintree.js does client side encryption of the form fields before submission to the server. On my end I get a bunch of gibberish (this is expected). If a form validation error occurs, I want the form displayed again alerting the user of the error but I don't want any of the fields pre-populated because the pre-populated values are now the client side encrypted gibberish. Is there a method of doing this in the _validate function?

Answer 1

I was able to unset the value from within the form validation function. In my case the element is named foo and it only validates if it's set to bar:

function mymodule_myform_validate($form, &$form_state) {
  if ($form_state['input']['foo'] != 'bar') {
    unset($form_state['complete form']['foo']['#value']);
    form_error($form['foo'], 'foo is not equal to bar');
  }
}

If the user enters anything but bar in foo, we set a form error and they presented with the form again without anything in the foo field.

I'm not sure how/if the form state array is affected by, for example, the i18n or locale modules, but this should get you started.