Flutter Firebase GeoQueries is giving back a lot of false data-CodePudding

I am building a food ordering app like Uber eats. So, I am using flutter to make an app, however now I ran into a problem of finding the nearest restaurants.

I am currently storing location details using geoflutterfire package. Please see the picture attached.

Have a look into my code.

getLocation() async {
// Create a geoFirePoint

  GeoFirePoint center =
      geo.point(latitude: 28.706707247639613, longitude: 80.58572410373661);

// get the collection reference or query
  var collectionReference = _firestore.collection('locations');

  double radius = 5;
  String field = 'position';

  Stream<List<DocumentSnapshot>> stream = geo
      .collection(collectionRef: collectionReference)
      .within(center: center, radius: radius, field: field);

  stream.forEach((element) {
    element.forEach((e) {
      double fbLat = e.get('position')['geopoint'].latitude;
      double fbLng = e.get('position')['geopoint'].longitude;

      LatLng loc2 = LatLng(fbLat, fbLng);
      LatLng loc1 = LatLng(center.latitude, center.longitude);

      final distance =
          distanceBetweenTwoLocations(location1: loc1, location2: loc2);
      print('=======distance is ======');
      print('${distance / 1000}KM');
     
    });
  });
}

Yes, I am getting back nearest places from from database, however I am getting back 30 results, out of which only 6-7 are correct, and I think it is not efficient to scale because it is increasing my reads as well as overhead at client side to filter them.

Now my question is, how do I implement a perfect geoqueries to filter nearest restaurants and drivers in cloud firestore? Please help.

CodePudding user response：

Most geoquery implementations for Firestore (like the one

To limit the returned items to the circular radius you want, you need to post-process the results as you're doing. In my testing the queries read about 5x more documents than needed, with some queries (typically the ones with even fewer results) reading up to 15x more. Based on that, your results seem to be about average.

If you're interesting in learning more, I recommend checking out the video of a talk I did a few years ago: Querying Firebase and Firestore based on geographic location or distance.