For nesting JSON structures, allow certain fields to be designated for "raw passthrough"

Updated issue title so others find this topic when trying to do nested data.

Here's a utility function we're using in the interim. We call this from a custom Views JSON style output template, in place of what are normally calls to _views_json_encode_formatted():

/**
 * Encodes the provided nested array into JSON format, preserving the contents
 * of the specified field as-is as a raw, nested JSON value.
 *
 * @param $rows
 *   The nested array to encode into JSON.
 *
 * @param $jsonOptions
 *   The JSON encoder settings bitmask, if the format that would be passed for
 *   $options to PHP's json_encode() function.
 *
 * @param $previewAsHtml
 *   Whether or not the JSON is being previewed in the Views UI interface.
 *
 * @param $rootObjectName
 *   The name of the root value in the array.
 *
 * @param $nestedFieldName
 *   The name of the field in each row that is to be protected from escaping
 *   because it already contains JSON that should be passed through raw.
 *
 * @return string
 *   Either the JSON encoded string on success; or FALSE on
 *   failure.
 */
function render_unfiltered_nested_json($rows, $jsonOptions, $previewAsHtml, $rootObjectName, $nestedFieldName) {
  if (isset($rows[$rootObjectName])) {
    /* Pick a random number to include in the pattern, to further reduce the
     * chances of coming across content that just happens to match our
     * placeholder pattern.
     */
    $rawFieldPlaceholderPattern =
      sprintf(
        "%s_PLACEHOLDER_%d_",
        $nestedFieldName,
        rand(1, 2000));

    $unescapedItems = array();

    $events =& $rows[$rootObjectName];

    foreach ($events as $index => &$event) {
      if (isset($event[$nestedFieldName])) {
        $placeholderContent = $rawFieldPlaceholderPattern . $index;

        /* JSON wraps the content in quotes, making it a string.
         * For us to nest the JSON as JSON, we need to strip the quotes, so
         * we include them in the key so that strtr() handle the replacement.
         */
        $placeholderKey     = '"' . $placeholderContent . '"';

        $unescapedItems[$placeholderKey]  = trim($event[$nestedFieldName]);
        $event[$nestedFieldName]          = $placeholderContent;
      }
    }

    if ($previewAsHtml) {
      $jsonContent = _views_json_encode_formatted($rows, $jsonOptions);
    }
    else {
      $jsonContent = _views_json_json_encode($rows, $jsonOptions);
    }

    /* Replace the placeholders with the corresponding raw JSON values we saved
     * before we passed the object through json_encode().
     */
    $result = strtr($jsonContent, $unescapedItems);
  }
  else {
    if ($previewAsHtml) {
      $result = _views_json_encode_formatted($rows, $jsonOptions);
    }
    else {
      $result = _views_json_json_encode($rows, $jsonOptions);
    }
  }

  return $result;
}

A sample template:

/**
 * @file views-views-json-style-simple--json-events.tpl.php
 *  Template for rendering events and their products using
 *  the Views JSON style plugin and the "simple" format.
 *
 *  Variables:
 *  - $view: The View object.
 *  - $rows: Hierarchical array of key=>value pairs to convert to JSON.
 *  - $options: Array of options for this style.
 *
 * @ingroup views_templates
 */

$jsonp_prefix = $options['jsonp_prefix'];

if ($view->override_path) {
  // We're inside a live preview where the JSON is pretty-printed.
  $json = render_unfiltered_nested_json($rows, $options, TRUE, 'events', 'relatedItems');

  if ($jsonp_prefix) {
    $json = "$jsonp_prefix($json)";
  }

  print "$json";
}
else {
  $json = render_unfiltered_nested_json($rows, $bitmask, FALSE, 'events', 'relatedItems');

  if ($options['remove_newlines']) {
    $json = preg_replace(array('/\\\\n/'), '', $json);
  }

  if (isset($_GET[$jsonp_prefix]) && $jsonp_prefix) {
    $json = check_plain($_GET[$jsonp_prefix]) . '(' . $json . ')';
  }

  if ($options['using_views_api_mode']) {
    // We're in Views API mode.
    print $json;
  }
  else {
    // We want to send the JSON as a server response so switch the content
    // type and stop further processing of the page.
    $content_type = ($options['content_type'] == 'default') ? 'application/json' : $options['content_type'];

    drupal_add_http_header("Content-Type", "$content_type; charset=utf-8");

    print $json;

    drupal_page_footer();

    exit;
  }
}

@phponwebsites: Please open a different issue. Your request has nothing to do with JSON or this ticket, as far as I can tell.

We looked at Rest JSON but the output was too verbose for the use case we had. Views Datasource was a lot closer to ideal because we could select just the data we wanted.