如何利用NodeJS中的firebase cloud函数从firebase实时数据库中查找最近的LatLng

Question

• 未配置计费帐户。外部网络无法访问，配额受到严重限制。配置计费帐户以删除这些限制
• 函数执行时间为60002 ms，结束时状态为'timeout'

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

//https://*********.cloudfunctions.net/searchNearbyLatLng?originlat=23.7939419&originlng=90.3888492
exports.searchNearbyLatLng = functions.https.onRequest((request, response) => {

  let lat1Param = request.query.originlat;
  let lng1Param = request.query.originlng;

  let rootRef = admin.database().ref('riders_online');
  rootRef.once('value', gotData, errData);


  function gotData(data) {
    let items = data.val();
    let keys = Object.keys(items);
    for (let i = 0; i < keys.length; i++) {
      let key = keys[i];
      let item = items[key];
      //console.log(item.isUserRequested, item.riderOriginLatitude, key);
      let distance = getDistance( lat1Param, lng1Param, data.val().riderOriginLatitude, data.val().riderOriginLongitude );
      if( distance < 1 ) {
        response.send('Record' + item.riderOriginLatitude);
      }
    }
  }

  function errData(error) {
    console.log("Something went wrong.");
    console.log(error);
  }

  function getDistance( latitude1, longitude1, latitude2, longitude2 ) {
    let earth_radius = 6371;
    let dLat = degToRad( latitude2 - latitude1 );
    let dLng = degToRad( longitude2 - longitude1 );
    let a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(degToRad(latitude1)) * Math.cos(degToRad(latitude2)) * Math.sin(dLng/2) * Math.sin(dLng/2);
    let c = 2 * Math.asin(Math.sqrt(a));
    let d = earth_radius * c;
    return d;
  }
  function degToRad(degrees){
    let pi = Math.PI;
    return degrees * (pi/180);
  }

}, err => {
    console.error(err.stack);
    response.status(500).send('Unexpected error.');
});

Answer 1

因为Firebase不支持地理空间查询，所以我建议使用geohash。

这在这个firebase博客上有很好的暴露：

https://firebase.googleblog.com/2013/09/geofire-location-queries-for-fun-and.html