Extendiendo la respuesta (correcta) de Clive, trabajé a través del código IFE. Realmente no necesitaba un módulo completo dedicado a esto, así que adopté algunos fragmentos aquí y allá para obtener el resultado que necesitaba. He marcado su respuesta como correcta porque, en última instancia, es la respuesta correcta.
El código está debajo, todo el crédito va para Clive y el equipo de IFE: solo quería presentar la versión simplificada para cualquiera que busque una respuesta similar.
// Standard gear - do some custom validation and set the errors
// as you go..
//
// Once all the validation has been done, call MODULE_errors_reset
// which will return an array of all errors against their ID.
// Expose this array however you like to your template, or loop
// over your form adding a #suffix to each element with an error
//
function MODULE_form_name_validate($form, &$form_state) {
drupal_set_message("validating...");
form_set_error("description", "There is an error here!!!!");
form_set_error("tags", "Yep, and here too!!!");
$reset_errors = MODULE_errors_reset( $form );
drupal_set_message( "<pre>" . print_r( $reset_errors, true ) . "</pre>" );
}
// This part is adopted from IFE. It's changed in two ways, it returns
// an array (which also merges with its recursive self).
// And it also skips all the 'display' stuff present in the original
// Essentially it extracts out the error messages from the session and unsets
// them. I am assuming that Drupal 7 marks the success of a validation based not
// whether the SESSION variable contains anything, the SESSION seems to be only
// for the message at the top of the screen.
//
function MODULE_errors_reset( $element ) {
if( ! isset( $_SESSION[ 'messages' ] ) ) {
return;
}
$reset_errors = array();
// Recurse through all children.
foreach( element_children( $element ) as $key ) {
if( isset( $element[ $key ] ) && $element[ $key ] ) {
$reset_errors += MODULE_errors_reset( $element[ $key ] );
}
}
// Check for errors and settings
$errors = form_get_errors();
$element_id = implode( '][', $element[ '#parents' ] );
if ( !empty( $errors[ $element_id ] )) {
$error_message = $errors[ $element_id ];
// Get error id
$error_id = array_search( $error_message, $_SESSION[ 'messages' ][ 'error' ] );
if( $error_id !== FALSE ) {
unset( $_SESSION[ 'messages' ][ 'error' ][ $error_id ] );
$_SESSION[ 'messages' ][ 'error' ] = array_values( $_SESSION[ 'messages' ][ 'error' ] );
if( count( $_SESSION[ 'messages' ][ 'error' ] ) <= 0 ) {
unset( $_SESSION[ 'messages' ][ 'error' ] );
}
$reset_errors[ $element[ '#id' ] ] = $error_message;
}
}
return $reset_errors;
}
// If there are no form errors, we still hit here, even after the 'reset', this is
// a good thing.
function MODULE_form_name_submit( $form, &$form_submit ) {
drupal_set_message("submited!");
}