geopipes-elasticsearch-backend/query/geo_distance.js

// Reverse GeoCoding geo_distance Query

var baseQuery = require('./reverse_geo_base');

module.exports = function( centroid, opts ){

  if( !opts ){ opts = {}; }

  var options = {
    distance: opts.distance || '50km',
    size: opts.size || 1,
    field: opts.field || 'center_point'
  }

  var query = baseQuery( centroid, options );

  var filter = {
    'geo_distance' : {
      'distance': options.distance,
      'distance_type': 'plane',
      'optimize_bbox': 'indexed',
      '_cache': true // Speed up duplicate queries. Memory impact?
    }
  }

  filter.geo_distance[ options.field ] = {
    'lat': Number( centroid.lat ).toFixed(2), // @note: make filter cachable
    'lon': Number( centroid.lon ).toFixed(2)  // precision max ~1.113km off
  }

  // Add geo_distance specific filter conditions
  query.query.filtered.filter.bool.must.push( filter );

  return query;
}