FlutterでFirebaseを入れて情報を取得する #03

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';

import 'apple_maps.dart';

class GpsPositionFirestore extends StatefulWidget {
  const GpsPositionFirestore({Key? key}) : super(key: key);

  @override
  State<GpsPositionFirestore> createState() => _GpsPositionFirestoreState();
}


class _GpsPositionFirestoreState extends State<GpsPositionFirestore> {
  GeoPoint pos = const GeoPoint(0.0, 0.0);
  String currentLocationText = 'no data';

  /// Firestoreから値を取得する
  Future<GeoPoint> fetchGeoPoint() async {
    final snapShot = await FirebaseFirestore.instance.collection('position').get();
    final pos = snapShot.docs.first.data()['geopoint'];
    return pos;
  }

  @override
  void initState() {
    super.initState();
    fetchGeoPoint().then((GeoPoint pos) {
      setState(() {
        this.pos = pos;
        currentLocationText = '$this.pos';
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('GPS Firestore'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              currentLocationText,
              style: Theme.of(context).textTheme.headline4,
            ),
            ElevatedButton(
              onPressed: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => AppleMaps(pos.latitude, pos.longitude)),
                );
              },
              child: const Text('Mapページへ'),
            ),
          ],
        ),
      ),
    );
  }
}