想从 flutter cloud firestore 中的多个文档中获取特定的文档字段

Question

this image have the Database

想抓取所有文档的经纬度显示在flutter map(leaflet)中

FlutterMap(
      options: MapOptions(
        center: latLng.LatLng(51.5, -0.09),
        zoom: 13.0,
      ),
      layers: [
        TileLayerOptions(
            urlTemplate: "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png",
            subdomains: ['a', 'b', 'c']),
        MarkerLayerOptions(
          markers: [
            Marker(
              width: 80.0,
              height: 80.0,
              point: latLng.LatLng(51.5, -0.09),
              builder: (ctx) => Container(
                child: Icon(
                  Icons.circle,
                  size: 30,
                  color: dc,
                ),
              ),
            ),
          ],
        ),
      ],
    );

我把第 15 行放在示例中，我想访问所有用户的经纬度。请帮忙，提前致谢

Answer 1

• 首先，您必须为您的 shopkeepers.
获取文件
• 然后，遍历这些文档，提取纬度和经度值，并将它们添加到列表中。

Future<List<LatLng>> getCordsFromFirebase() async {
List<LatLng> coordinatesList=[];
var results = await FirebaseFirestore.instance.collection('shopkeepers').get();

for (DocumentSnapshot item in results.docs){
coordinatesList.add(LatLng(item.data()['latitidue'], item.data()['longitude]));
 }
print('Length of cords list is: ' + coordinatesList.length.toString());//
return coordinatesList;
}