I have an error using the null safety version

[PaoloP98]

I have an error using the null safety version

E/flutter ( 687): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: type '(BaseCluster, double, double) => MapMarker' is not a subtype of type '((BaseCluster?, double?, double?) => MapMarker)?'

I initialised the cluster in this way:

      minZoom: minZoom,
      maxZoom: maxZoom,
      radius: 150,
      extent: 4096,
      nodeSize: 64,
      points: markers,
      createCluster: (
        BaseCluster cluster,
        double lng,
        double lat,
      ) =>
          MapMarker(
        id: cluster.id.toString(),
        latitude: lat,
        longitude: lng,
        isCluster: cluster.isCluster,
        clusterId: cluster.id,
        pointsSize: cluster.pointsSize,
        childMarkerId: cluster.childMarkerId,
      ),
    );

Do you know what the problem is?

Originally posted by @PaoloP98 in #12 (comment)

[sunderee]

The problem seems to be related to this line taken out of the official documentation:

...
createCluster: (BaseCluster cluster, double longitude, double latitude) {
    // something here
});
...

If you look at the error message, it tells you that types BaseCluster, and two doubles are nullable. Therefore, you should try replacing what you currently have with

createCluster: (BaseCluster? cluster, double? longitude, double? latitude) {
    // something here
});

Edit: fixed wording.

[PaoloP98]

I tried that but I can't figure out what createCluster should return if cluster equals null

[vishnuraj-dev]

Same here, did you find any solution.

[PaoloP98]

Same here, did you find any solution.

I solved it this way: I added an if to check if the cluster == null and in that case I return a mapmarker without assigning values. The only value I pass is the id because in my constructor is required

return Fluster<MapMarker>(
        minZoom: minZoom,
        maxZoom: maxZoom,
        radius: 150,
        extent: 4096,
        nodeSize: 64,
        points: markers,
        createCluster: (BaseCluster? cluster, double? longitude, double? latitude) {
          if (cluster == null) {
            return MapMarker(id: "");
          }
          return MapMarker(
            id: cluster.id.toString(),
            latitude: latitude,
            longitude: longitude,
            isCluster: cluster.isCluster,
            clusterId: cluster.id,
            pointsSize: cluster.pointsSize,
            childMarkerId: cluster.childMarkerId,
          );
        });

[0x7061]

@alfonsocejudo Can you maybe update the documentation and elaborate on how to use it if the cluster is nil ?

[digiboridev]

  final Fluster<MapMarker> fluster = Fluster<MapMarker>(
        minZoom: 10, // The min zoom at clusters will show
        maxZoom: 20, // The max zoom at clusters will show
        radius: 150, // Cluster radius in pixels
        extent: 2048, // Tile extent. Radius is calculated with it.
        nodeSize: 64, // Size of the KD-tree leaf node.
        points: newMarkers, // The list of markers created before
        createCluster:
            (BaseCluster? cluster, double? longitude, double? latitude) {
          if (cluster != null) {
            return MapMarker(
              id: cluster.id.toString(),
              position: LatLng(latitude!, longitude!),
              icon: icon,
              isCluster: cluster.isCluster,
              clusterId: cluster.id,
              pointsSize: cluster.pointsSize,
              childMarkerId: cluster.childMarkerId,
            );
          }
        });

class MapMarker extends Clusterable {
  final String id;
  final LatLng position;
  final BitmapDescriptor icon;
  MapMarker({
    required this.id,
    required this.position,
    required this.icon,
    isCluster = false,
    clusterId,
    pointsSize,
    childMarkerId,
  }) : super(
          markerId: id,
          latitude: position.latitude,
          longitude: position.longitude,
          isCluster: isCluster,
          clusterId: clusterId,
          pointsSize: pointsSize,
          childMarkerId: childMarkerId,
        );
  Marker toMarker() => Marker(
        markerId: MarkerId(id),
        position: LatLng(
          position.latitude,
          position.longitude,
        ),
        icon: icon,
      );
}

Unhandled Exception: type '(BaseCluster?, double?, double?) => MapMarker?' is not a subtype of type '((BaseCluster?, double?, double?) => MapMarker)?'

Whats wrong?