farmOS/modules/farm/farm_api/farm_api.module

<?php

/**
 * @file
 * Farm API module.
 */

define('FARM_API_VERSION', '1.0');

/**
 * Implements hook_permission().
 */
function farm_api_permission() {
  $perms = array(
    'access farm api info' => array(
      'title' => t('Access the farmOS API info endpoint'),
    ),
  );
  return $perms;
}

/**
 * Implements hook_menu().
 */
function farm_api_menu() {

  // General farm information JSON endpoint.
  $items['farm.json'] = array(
    'page callback' => 'farm_api_info',
    'access arguments' => array('access farm api info'),
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Farm info API callback.
 */
function farm_api_info() {
  global $base_url, $conf, $user;
  $info = array(
    'name' => $conf['site_name'],
    'url' => $base_url,
    'api_version' => FARM_API_VERSION,
  );
  if (!empty($user->uid)) {
    $info['user'] = array(
      'uid' => $user->uid,
      'name' => $user->name,
      'mail' => $user->mail,
    );
  }
  drupal_json_output($info);
}

/**
 * Implements hook_restws_request_alter().
 */
function farm_api_restws_request_alter(array &$request) {

  // If the format is not JSON, bail.
  if ($request['format']->getName() != 'json') {
    return;
  }

  // Build a field alias map to remove the 'field_farm_' prefix.
  $prefix = 'field_farm_';
  $alias_map = farm_api_field_alias_map($prefix);

  // In order to handle URL query string filters, we need to perform the alias
  // translation on all GET parameters. The restws module filters based on the
  // output of drupal_get_query_parameters(), which uses the $_GET global.
  foreach ($_GET as $name => &$value) {
    if (array_key_exists($name, $alias_map)) {
      $_GET[$alias_map[$name]] = $_GET[$name];
      unset($_GET[$name]);
    }
  }

  // If the payload is empty, bail.
  if (empty($request['payload'])) {
    return;
  }

  // Decode the payload JSON.
  $payload = drupal_json_decode($request['payload']);

  // If the payload could not be decoded, bail.
  if (empty($payload)) {
    return;
  }

  // Iterate through the fields in the payload. If any match a mapped alias,
  // translate it to use the real field name. Keep track of whether or not any
  // changes were made.
  $changed = FALSE;
  foreach ($payload as $key => $value) {
    if (array_key_exists($key, $alias_map)) {
      $payload[$alias_map[$key]] = $payload[$key];
      unset($payload[$key]);
      $changed = TRUE;
    }
  }

  // If we changed the payload, re-encode it as JSON.
  if ($changed) {
    $request['payload'] = drupal_json_encode($payload);
  }
}

/**
 * Implements hook_restws_response_alter().
 */
function farm_api_restws_response_alter(&$response, $function, $formatName, $resourceController) {

  // If the format is not JSON, bail.
  if ($formatName != 'json') {
    return;
  }

  // If the response contains a list of entities, iterate through them and
  // pass each to farm_api_restws_response_alter_item().
  if (!empty($response['list'])) {
    foreach ($response['list'] as &$item) {
      farm_api_restws_response_alter_item($item);
    }
  }

  // Otherwise, process the response directly.
  else {
    farm_api_restws_response_alter_item($response);
  }
}

/**
 * Helper function for altering a restws response item.
 *
 * @param $item
 *   The restws response item, passed by reference.
 */
function farm_api_restws_response_alter_item(&$item) {

  // Build a field alias map to remove the 'field_farm_' prefix.
  $prefix = 'field_farm_';
  $alias_map = farm_api_field_alias_map($prefix);

  // Flip the alias map so that it is keyed by actual field name.
  $field_aliases = array_flip($alias_map);

  // Iterate through the item properties.
  foreach (array_keys($item) as $key) {

    // If the field name exists in the alias map, replace it with the alias.
    if (array_key_exists($key, $field_aliases)) {
      $item[$field_aliases[$key]] = $item[$key];
      unset($item[$key]);
    }

    // Remove Feeds properties.
    $feeds_prefixes = array(
      'feed_',
      'feeds_',
    );
    foreach ($feeds_prefixes as $prefix) {
      if (strpos($key, $prefix) === 0) {
        unset($item[$key]);
      }
    }
  }
}

/**
 * Build a field alias map for restws requests and responses.
 *
 * @param string $prefix
 *   The field name prefix to remove from fields.
 *
 * @return array
 *   Returns an array of field names with the alias as the key, and the actual
 *   field name as the value.
 */
function farm_api_field_alias_map($prefix) {

  // Start an empty map array.
  $alias_map = array();

  // Load a list of all fields.
  $fields = field_info_field_map();

  // Iterate through the fields to build an alias map.
  foreach ($fields as $field_name => $field_info) {

    // If the field is a field_collection, skip it. Field collection alias are a
    // special case that are currently handled by the restws_field_collection
    // module in farmOS.
    if ($field_info['type'] == 'field_collection') {
      continue;
    }

    // If the field name starts with the prefix, add it to the map.
    $alias = str_replace($prefix, '', $field_name);
    $alias_map[$alias] = $field_name;
  }

  // Return the alias map.
  return $alias_map;
}