isbn.module in ISBN Field 7

Maintains a consistant relationship between nodes and ISBNs.

File

isbn.module

<?php

/**
 * @file
 *  Maintains a consistant relationship between nodes and ISBNs.
 */

/**
 * Implements hook_field_info().
 */
function isbn_field_info() {
  return array(
    'isbn' => array(
      'label' => 'ISBN',
      'description' => t('This field stores and renders ISBN numbers.'),
      'default_widget' => 'isbn_textfield',
      'default_formatter' => 'isbn_default',
      'property_type' => 'text',
    ),
  );
}

/**
 * Implements hook_field_validate().
 */
function isbn_field_validate($obj_type, $object, $field, $instance, $langcode, $items, &$errors) {
  foreach ($items as $delta => $item) {
    $isbn = isbn_clean_data($item['isbn']);
    if ($isbn != '' && !isbn_check_10($isbn) && !isbn_check_13($isbn)) {
      if (strlen($isbn) < 10 && strlen($isbn) > 13) {
        $message = t('"%isbn" isn\'t a valid ISBN number. A valid ISBN number has 10 or 13 digits.', array(
          '%isbn' => $isbn,
        ));
      }
      else {
        if (strlen($isbn) == 10 && !isbn_check_10($isbn)) {
          $message = t('"%isbn" isn\'t a valid 10 digit ISBN number.', array(
            '%isbn' => $isbn,
          ));
        }
        if (strlen($isbn) == 13 && !isbn_check_13($isbn)) {
          $message = t('"%isbn" isn\'t a valid 13 digit ISBN number.', array(
            '%isbn' => $isbn,
          ));
        }
      }
      $errors[$field['field_name']][$langcode][$delta][] = array(
        'error' => "isbn_invalid",
        'message' => $message,
      );
    }
  }
}

/**
 * Implements hook_field_widget_error().
 */
function isbn_field_widget_error($element, $error, $form, &$form_state) {
  form_error($element, $error['message']);
}

/**
 * Implements hook_field_is_empty().
 */
function isbn_field_is_empty($item, $field) {
  return empty($item['isbn']);
}

/**
 * Implements hook_field_formatter_info().
 */
function isbn_field_formatter_info() {
  $formats = array(
    'isbn_default' => array(
      'label' => t('Not formated ISBN'),
      'description' => t('Display the ISBN number without format.'),
      'field types' => array(
        'isbn',
      ),
    ),
  );
  return $formats;
}

/**
 * Implements hook_field_formatter_view().
 */
function isbn_field_formatter_view($object_type, $object, $field, $instance, $langcode, $items, $display) {
  $element = array();
  switch ($display['type']) {
    case 'isbn_default':
      foreach ($items as $delta => $item) {
        $element[$delta] = array(
          '#markup' => $item['isbn'],
        );
      }
      break;
  }
  return $element;
}

/**
 * Implements hook_field_widget_info().
 */
function isbn_field_widget_info() {
  return array(
    'isbn_textfield' => array(
      'label' => t('Text field'),
      'field types' => array(
        'isbn',
      ),
      'settings' => array(
        'size' => 13,
      ),
    ),
  );
}

/**
 * Implements hook_field_widget_settings_form().
 */
function isbn_field_widget_settings_form($field, $instance) {
  $widget = $instance['widget'];
  $settings = $widget['settings'];
  $form['size'] = array(
    '#type' => 'textfield',
    '#title' => t('Size of textfield'),
    '#default_value' => $settings['size'],
    '#required' => TRUE,
    '#element_validate' => array(
      '_element_validate_integer_positive',
    ),
  );
  return $form;
}

/**
 * Implements hook_field_widget_form().
 */
function isbn_field_widget_form(&$form, &$form_state, $field, $instance, $langcode, $items, $delta, $base) {
  $element = $base;
  $element['isbn'] = $base + array(
    '#type' => 'textfield',
    '#default_value' => isset($items[$delta]['isbn']) ? $items[$delta]['isbn'] : NULL,
    '#size' => $instance['widget']['settings']['size'],
    '#prefix' => '<div class="text-full-wrapper">',
    '#suffix' => '</div>',
  );
  return $element;
}

/**
 * Implements hook_field_presave().
 */
function isbn_field_presave($entity_type, $entity, $field, $instance, $langcode, &$items) {
  if ($field['type'] == 'isbn') {
    foreach ($items as $delta => $item) {

      // Cleaning the data before saving it.
      if (isset($item['isbn'])) {
        $items[$delta]['isbn'] = isbn_clean_data($item['isbn']);
      }
    }
  }
}

/**
 * Remove all non-valid characters.
 *
 * @param $isbn
 *   The ISBN number typed by the user.
 *
 * @return
 *   The ISBN number without invalid characters.
 */
function isbn_clean_data($isbn) {
  return preg_replace('/([^xX0-9]*)/', "", $isbn);
}

/**
 * Check if the ISBN number is a valid 10 digit.
 *
 * @param $isbn
 *   The ISBN number with only valid characters.
 *
 * @return
 *   True if it's a valid 10 digit ISBN number, false otherwise.
 */
function isbn_check_10($isbn) {
  if (strlen($isbn) < 10) {
    return FALSE;
  }
  $check = 0;
  for ($i = 0; $i < 9; $i++) {
    $check += (10 - $i) * $isbn[$i];
  }
  $tenth = $isbn[9];

  // tenth digit (aka checksum or check digit)
  $check += strtoupper($tenth) == 'X' ? 10 : $tenth;
  return $check % 11 == 0;
}

/**
 * Check if the ISBN number is a valid 13 digit.
 *
 * @param $isbn
 *   The ISBN number with only valid characters.
 *
 * @return
 *   True if it's a valid 13 digit ISBN number, false otherwise.
 */
function isbn_check_13($isbn) {
  if (strlen($isbn) < 13) {
    return FALSE;
  }
  $check = 0;
  for ($i = 0; $i < 13; $i += 2) {
    $check += $isbn[$i];
  }
  for ($i = 1; $i < 12; $i += 2) {
    $check += 3 * $isbn[$i];
  }
  return $check % 10 == 0;
}

Functions

Name	Description
isbn_check_10	Check if the ISBN number is a valid 10 digit.
isbn_check_13	Check if the ISBN number is a valid 13 digit.
isbn_clean_data	Remove all non-valid characters.
isbn_field_formatter_info	Implements hook_field_formatter_info().
isbn_field_formatter_view	Implements hook_field_formatter_view().
isbn_field_info	Implements hook_field_info().
isbn_field_is_empty	Implements hook_field_is_empty().
isbn_field_presave	Implements hook_field_presave().
isbn_field_validate	Implements hook_field_validate().
isbn_field_widget_error	Implements hook_field_widget_error().
isbn_field_widget_form	Implements hook_field_widget_form().
isbn_field_widget_info	Implements hook_field_widget_info().
isbn_field_widget_settings_form	Implements hook_field_widget_settings_form().