<?php

/**

 * @file

 * Callbacks provided by the form system.

 */

/**

 * @addtogroup callbacks

 * @{

 */

/**

 * Perform a single batch operation.

 *

 * Callback for batch_set().

 *

 * @param $MULTIPLE_PARAMS

 *   Additional parameters specific to the batch. These are specified in the

 *   array passed to batch_set().

 * @param $context

 *   The batch context array, passed by reference. This contains the following

 *   properties:

 *   - 'finished': A float number between 0 and 1 informing the processing

 *     engine of the completion level for the operation. 1 (or no value

 *     explicitly set) means the operation is finished: the operation will not

 *     be called again, and execution passes to the next operation or the

 *     callback_batch_finished() implementation. Any other value causes this

 *     operation to be called again; however it should be noted that the value

 *     set here does not persist between executions of this callback: each time

 *     it is set to 1 by default by the batch system.

 *   - 'sandbox': This may be used by operations to persist data between

 *     successive calls to the current operation. Any values set in

 *     $context['sandbox'] will be there the next time this function is called

 *     for the current operation. For example, an operation may wish to store a

 *     pointer in a file or an offset for a large query. The 'sandbox' array key

 *     is not initially set when this callback is first called, which makes it

 *     useful for determining whether it is the first call of the callback or

 *     not:

 *     @code

 *       if (empty($context['sandbox'])) {

 *         // Perform set-up steps here.

 *       }

 *     @endcode

 *     The values in the sandbox are stored and updated in the database between

 *     http requests until the batch finishes processing. This avoids problems

 *     if the user navigates away from the page before the batch finishes.

 *   - 'message': A text message displayed in the progress page.

 *   - 'results': The array of results gathered so far by the batch processing.

 *     This array is highly useful for passing data between operations. After

 *     all operations have finished, this is passed to callback_batch_finished()

 *     where results may be referenced to display information to the end-user,

 *     such as how many total items were processed.

 */

function callback_batch_operation($MULTIPLE_PARAMS, &$context) {

  if (!isset($context['sandbox']['progress'])) {

    $context['sandbox']['progress'] = 0;

    $context['sandbox']['current_node'] = 0;

    $context['sandbox']['max'] = db_query('SELECT COUNT(DISTINCT nid) FROM {node}')->fetchField();

  }

  // For this example, we decide that we can safely process

  // 5 nodes at a time without a timeout.

  $limit = 5;

  // With each pass through the callback, retrieve the next group of nids.

  $result = db_query_range("SELECT nid FROM {node} WHERE nid > %d ORDER BY nid ASC", $context['sandbox']['current_node'], 0, $limit);

  while ($row = db_fetch_array($result)) {

    // Here we actually perform our processing on the current node.

    $node = node_load($row['nid'], NULL, TRUE);

    $node->value1 = $options1;

    $node->value2 = $options2;

    node_save($node);

    // Store some result for post-processing in the finished callback.

    $context['results'][] = check_plain($node->title);

    // Update our progress information.

    $context['sandbox']['progress']++;

    $context['sandbox']['current_node'] = $node->nid;

    $context['message'] = t('Now processing %node', array('%node' => $node->title));

  }

  // Inform the batch engine that we are not finished,

  // and provide an estimation of the completion level we reached.

  if ($context['sandbox']['progress'] != $context['sandbox']['max']) {

    $context['finished'] = $context['sandbox']['progress'] / $context['sandbox']['max'];

  }

}

/**

 * Complete a batch process.

 *

 * Callback for batch_set().

 *

 * This callback may be specified in a batch to perform clean-up operations, or

 * to analyze the results of the batch operations.

 *

 * @param $success

 *   A boolean indicating whether the batch has completed successfully.

 * @param $results

 *   The value set in $context['results'] by callback_batch_operation().

 * @param $operations

 *   If $success is FALSE, contains the operations that remained unprocessed.

 */

function callback_batch_finished($success, $results, $operations) {

  if ($success) {

    // Here we do something meaningful with the results.

    $message = t("!count items were processed.", array(

      '!count' => count($results),

      ));

    $message .= theme('item_list', array('items' => $results));

    drupal_set_message($message);

  }

  else {

    // An error occurred.

    // $operations contains the operations that remained unprocessed.

    $error_operation = reset($operations);

    $message = t('An error occurred while processing %error_operation with arguments: @arguments', array(

      '%error_operation' => $error_operation[0],

      '@arguments' => print_r($error_operation[1], TRUE)

    ));

    drupal_set_message($message, 'error');

  }

}