isbn.module in ISBN Field 6.0

Maintains a consistant relationship between nodes and ISBNs.

File

isbn.module

<?php

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

/**
 * Implementation of hook_menu().
 */
function isbn_menu() {
  $items = array();
  $items['isbn'] = array(
    'title' => 'ISBN Conversion',
    'type' => MENU_CALLBACK,
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'isbn_form',
    ),
    'access arguments' => array(
      'access content',
    ),
    'weight' => 7,
  );
  return $items;
}
function isbn_nodeapi(&$node, $op, $a3 = NULL, $a4 = NULL) {
  switch ($op) {
    case 'insert':
    case 'update':
      if ($node->isbn['isbn']) {
        $isbn_values = $node->isbn['isbn'];
      }
      else {
        $isbn_values = isbn_find_isbns($node);
      }
      db_query("DELETE FROM {isbn_node} WHERE nid = %d", $node->nid);
      if ($isbn_values) {
        foreach ($isbn_values as $isbn_value) {
          if ($isbn_value['isbn'] > 1) {
            $isbn->isbn = $isbn_value['isbn'];
            $isbn->isbn10 = $isbn_value['isbn10'];
            $isbn->nid = $node->nid;
            drupal_write_record('isbn_node', $isbn);
          }
        }
      }
      break;
    case 'load':
      $result = db_query("SELECT * FROM {isbn_node} WHERE nid = %d", $node->nid);
      while ($isbn_node = db_fetch_object($result)) {
        if ($isbn_node) {
          $isbn = array(
            'isbn' => $isbn_node->isbn,
            'isbn10' => $isbn_node->isbn10,
          );
          drupal_alter('isbn', $isbn);
          $node->isbn[] = $isbn;
        }
      }

      //return $node;
      break;
    case 'delete':
      db_query("DELETE FROM {isbn_node} WHERE nid = %d", $node->nid);
      break;
  }
}

//This might be useful to use with case 'load':
function isbn_load_nid($node) {
  $result = db_query("SELECT * FROM {isbn_node} WHERE nid = %d", $node->nid);
  while ($isbn_node = db_fetch_object($result)) {
    if ($isbn_node) {
      $isbn = array(
        'isbn' => $isbn_node->isbn,
        'isbn10' => $isbn_node->isbn10,
      );
      drupal_alter('isbn', $isbn);
      $node->isbn[] = $isbn;
    }
  }
  return $node;
}
function isbn_find_isbns($node) {

  //This should not be so hardcoded but for now it is.

  //$isbn_fields = variable_get('isbn_fields', null);
  $isbn_fields = array(
    'field_isbn',
  );
  if ($isbn_fields) {
    $isbns = array();
    foreach ($isbn_fields as $isbn_field) {
      if ($node->{$isbn_field}) {
        if (is_array($node->{$isbn_field})) {
          foreach ($node->{$isbn_field} as $field) {
            $isbns = isbn_build_isbns(isbn_clean_field($field['value']));
            $isbn13 = $isbns['isbn'];
            $isbn_list[$isbn13] = $isbns;
          }
        }
      }
    }
  }
  return $isbn_list;
}
function isbn_clean_field($field) {
  $bad_chars = array(
    "-",
    "/",
    " ",
  );
  $isbn = strtoupper(trim(str_replace($bad_chars, "", $field)));
  if (strlen($isbn) > 9) {
    $test = substr($isbn, 10, 1);
    if (is_numeric($test)) {
      $isbn = substr($isbn, 0, 13);
    }
    else {
      $isbn = substr($isbn, 0, 10);
    }
  }
  else {
    $isbn = null;
  }
  return $isbn;
}
function isbn_build_isbns($isbn) {
  switch (strlen($isbn)) {
    case 10:
      if (substr($isbn, 9, 1) == isbn_check_10($isbn)) {
        $isbns['isbn10'] = $isbn;
        $check = isbn_check_13('978' . $isbn);
        $isbns['isbn'] = '978' . substr($isbn, 0, 9) . $check;
      }
      else {
      }
      break;
    case 13:
      if (substr($isbn, 12, 1) == isbn_check_13($isbn)) {
        $isbns['isbn'] = $isbn;
        $check = isbn_check_10(substr($isbn, 3, 10));
        $isbns['isbn10'] = substr($isbn, 3, 9) . $check;
      }
      break;
  }
  return $isbns;
}
function isbn_check_10($isbn) {
  for ($i = 0; $i < 9; $i++) {
    $digit = substr($isbn, $i, 1);
    $total = $total + $digit * (10 - $i);
  }
  $remainder = $total % 11;
  $check = 11 - $remainder;
  if ($check == 10) {
    $check = 'X';
  }
  elseif ($check == 11) {
    $check = 0;
  }
  return $check;
}
function isbn_check_13($isbn) {
  $weight = 1;
  for ($i = 0; $i < 12; $i++) {
    $digit = substr($isbn, $i, 1);
    $total = $total + $digit * $weight;

    //drupal_set_message(' i '.$i.' digit '.$digit.' x '.$weight.'Total '.$total);
    if ($weight == 1) {
      $weight = 3;
    }
    else {
      $weight = 1;
    }
  }
  $remainder = $total % 10;
  $check = 10 - $remainder;
  if ($check == 10) {
    $check = '0';
  }
  return $check;
}

//This is just used to check the ISBN formula.
function isbn_form() {
  $form['isbn'] = array(
    '#type' => 'textfield',
    '#title' => t('Give up an ISBN'),
    '#description' => t('Type in an isbn.'),
    '#required' => TRUE,
  );
  $form['submit'] = array(
    '#value' => 'go',
    '#type' => 'submit',
    '#submit' => array(
      'isbn_form_submit',
    ),
  );
  return $form;
}
function isbn_form_submit($form, $form_state) {
  $field = $form_state['values']['isbn'];
  if ($field) {
    $isbn = isbn_clean_field($field);
  }
  $isbns = isbn_build_isbns($isbn);
  drupal_set_message('10 digit ISBN ' . $isbns['isbn10']);
  drupal_set_message('13 digit ISBN ' . $isbns['isbn']);
  if (isbn_check_10($isbns['isbn10'])) {
    drupal_set_message('Valid ISBN 10');
  }
  if (isbn_check_13($isbns['isbn'])) {
    drupal_set_message('Valid ISBN 13');
  }
}
function isbn_isbn_alter($isbn) {
  $items = amazon_item_lookup($isbn['isbn10']);
  $isbn['amazon'] = array_pop($items);
  return $isbn;
}

Functions

Name	Description
isbn_build_isbns
isbn_check_10
isbn_check_13
isbn_clean_field
isbn_find_isbns
isbn_form
isbn_form_submit
isbn_isbn_alter
isbn_load_nid
isbn_menu	Implementation of hook_menu().
isbn_nodeapi