[移动开发]No Firebase App ‘[DEFAULT]‘ has been created - call Firebase.initializeApp() in Flutter and Firebase

• 问题原因
  装有Firebase的程序没有被初始化或者连接数据库,贸然地进行cloud firestore事务会出现问题
• 解决方案(flutter - dart)

Widget InitiaFirebaseApp(){
return FutureBuilder(
          // 初始化 FlutterFire
          future: Firebase.initializeApp(),
          builder: (context, snapshot) {
            // 检查错误
            if (snapshot.hasError) {
              print('hasError');
              return Center();
            }
            if (snapshot.connectionState == ConnectionState.done) {
              print('done');
              return Center();
            }

            //初始化完毕之后就可以进行Cloud Firestore的事务了
            return  Center(
              child: ElevatedButton(
                onPressed: (){
                  //将要完成Cloud Firestore的事务逻辑

                }, child: Text("Add"),
              ),
            );
          },
        );
        }