【Flutter】【Firestore】FutureBuilder<->StreamBuilderに切り替える

はじめに

FlutterでFirestoreを使う際に題のような切り替えをする際の備忘録。
FutureとStreamの違いに関してはこちらの記事が参考になった。

やりかた

それぞれ以下のように対応させる。

FutureBuilder

class ListFuture extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<QuerySnapshot>(
      future: FirebaseFirestore.instance.collection('hoge').get(),
      builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
        if (snapshot.hasError) return new Text('Error: ${snapshot.error}');
        switch (snapshot.connectionState) {
          case ConnectionState.waiting:
            return new Text('Loading...');
          default:
            return new ListView(
              children: snapshot.data.docs.map((DocumentSnapshot document) {
                return new ListTile(
                  title: new Text(document['hige']),
                  subtitle: new Text(document['hage']),
                );
              }).toList(),
            );
        }
      },
    );
  }
}

StreamBuilder

class ListStream extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder<QuerySnapshot>(
      stream: FirebaseFirestore.instance.collection('hoge').snapshots(),
      builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
        if (snapshot.hasError) return new Text('Error: ${snapshot.error}');
        switch (snapshot.connectionState) {
          case ConnectionState.waiting:
            return new Text('Loading...');
          default:
            return new ListView(
              children: snapshot.data.docs.map((DocumentSnapshot document) {
                return new ListTile(
                  title: new Text(document['hige']),
                  subtitle: new Text(document['hage']),
                );
              }).toList(),
            );
        }
      },
    );
  }
}