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Drupal - Find Nearby Nodes

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Lance Gliser

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I frequently need to find nodes near a location. The needs vary, but the actual search logic rarely changes. I use this function, along with the installed Location module to find nodes near a coordinate set. Note that this is Drupal 6 code. You'll need to adjust the variable handling for D7.

/**
 * Finds nodes near a given location based on parameters
 *
 * @param array $parameters
 *  $parameters['latitude'] Required - Latitude coordinate to search from
 *  $parameters['longitude'] Required - Latitude coordinate to search from
 *  $parameters['distance'] = 5 Distance in miles to search
 *  $parameters['distance_units'] = 'miles' - Option 'meters'
 *  $parameters['type'] Type of content to search
 *  $parameters['status'] Status of content to search
 */
function locations_get_nearby_nodes($params){
  $params += array(
    'distance' => 5,
    'distance_units' => 'miles'
  );

  // Distance needs to be converted from miles to meters!
  if( $params['distance_units'] == 'miles' ){
    $params['distance'] = $params['distance'] / 0.000621371192;
  }

  // Get location parameters we need
  $distance_sql = earth_distance_sql($params['longitude'], $params['latitude'], 'location');
  $latitude_range =  earth_latitude_range($params['longitude'], $params['latitude'], $params['distance']);
  $longitude_range =  earth_longitude_range($params['longitude'], $params['latitude'], $params['distance']);

  // Setup where logic
  $where = '';
  $query_args = array();

  // Location
  $where .=
    "location.latitude > %f
    AND location.latitude < %f
    AND location.longitude > %f
    AND location.longitude < %f";
  $query_args[] = $latitude_range[0];
  $query_args[] = $latitude_range[1];
  $query_args[] = $longitude_range[0];
  $query_args[] = $longitude_range[1];

  // Node type
  if( array_key_exists( 'type', $params ) ){
    $where .= " AND node.type = '%s'";
    $query_args[] = $params['type'];
  }

  // Node status
  if( array_key_exists( 'status', $params ) ){
    $where .= " AND node.status = %d";
    $query_args[] = $params['status'];
  }

  $query =
    "SELECT
      node.nid
      ,node.title
      ,location.lid
      ,location.latitude
      ,location.longitude
      ," . $distance_sql . " AS distance
    FROM node node
    JOIN location_instance location_instance ON node.vid = location_instance.vid
    JOIN location location ON location_instance.lid = location.lid
    WHERE " . $where . "
    ORDER BY distance ASC";

  $results = db_query($query, $query_args);

  $locations = array();

  while( $result = db_fetch_object($results) ){
    if( $params['distance_units'] == 'miles' ){
      $result->distance = $result->distance * 0.000621371192;
    }
    $result->node = node_load($result->nid);

    $locations[] = $result;
  }

  return $locations;
}