Drupal 7 multistep node forms are easy

The bane of multistep node forms are validation errors. But Drupal 7 has a cure. Not nice but a cure.

Slap #access = FALSE on form elements you dont want to see in the current step and then set up the Next button with #limit_validation_errors set to the elements you are about to see. The Prev button should get an empty #limit_validation_errors. Should field validation errors bother you, you can nuke those in hook_field_attach_validate.

<?php
define('MYMODULE_STORY_NODE_FORM_LAST_STEP', 2);
function mymodule_form_story_node_form_alter(&$form, $form_state) {
  $step = isset($form_state['storage']['step']) ? $form_state['storage']['step'] : 1;
  if ($step > 1) {
    $form['actions']['previous'] = array(
      '#type'   => 'submit',
      '#value'  => t('Previous'),
      '#submit' => array('mymodule_node_form_previous', 'node_form_submit_build_node'),
      // -1 so that it appears before the "Next" button added later.
      '#weight' => -1,
      '#limit_validation_errors' => array(),
    );
  }  
  if ($step < MYMODULE_STORY_NODE_FORM_LAST_STEP) {
    $form['actions']['next'] = array(
      '#type'   => 'submit',
      '#value'  => t('Next'),
      '#submit' => array('mymodule_node_form_next', 'node_form_submit_build_node'),
    );
  }
  $steps = mymodule_node_form_by_step();
  foreach ($steps as $key => $step_current) {
    if ($step_current == $step) {
      if (isset($form['actions']['next'])) {
        $form['actions']['next']['#limit_validation_errors'][] = array($key);
      }
    }
    else {
      $form[$key]['#access'] = FALSE;
    }
  }
}
function mymodule_node_form_by_step() {
  static $steps = array(
    // -1 means never show.
    'author'              => -1,
    'revision_information' => -1,
    'title'               => 1,
    'body'                => 2,
  );
  return $steps;
}
function mymodule_node_form_next($form, &$form_state) {
  if (!isset($form_state['storage']['step'])) {
    $form_state['storage']['step'] = 1;
  }
  if ($form_state['storage']['step'] == MYMODULE_STORY_NODE_FORM_LAST_STEP) {
    $form_state['rebuild'] = FALSE;
  }
  else {
    $form_state['rebuild'] = TRUE;
    $form_state['storage']['step']++;
  }
}
function mymodule_node_form_previous($form, &$form_state) {
  $form_state['rebuild'] = TRUE;
  $form_state['storage']['step']--;
  unset($form_state['node_preview']);
}
function mymodule_field_attach_validate($obj_type, $object, &$errors) {
  if (arg(0) == 'node' && (arg(1) == 'add' || arg(2) == 'edit')) {
    // foo and bar fields are handled elsewhere so nuke their errors.
    unset($errors['foo'], $errors['bar']);
  }
}
?>

Commenting on this Story is closed.

Can it be AJAX-ed ?

Submitted by Anonymous on Fri, 2011-07-22 05:56.

Great example of using the default node form structure to do multistep!

I'm trying to work out if it can be AJAX-ed so that only the form is loaded with each step rather than the entire page? Might this be possible or do I need to build such a form outside of the core node form?

Rick :)