我的应用程序连接到我的firebase存储，但没有连接到firebase数据库

Question

我设法将我的应用程序连接到firebase存储，我设法看到我上传到它的文档。但我不能把它链接到实时数据库。

数据库的规则：

{
  "rules": {
    ".read": true,
    ".write": true,
  }
}

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

class Bddtest extends StatefulWidget {
  @override
  _Bddtest createState() => _Bddtest();
}

class _Bddtest extends State<Bddtest> {
  var adder = 0;

  final ref = FirebaseDatabase().reference();

  void addData() {
    ref.child("test/").push().set({'add number': adder});
    adder++;
  }

  void printFirebase() {
    ref.once().then((DataSnapshot snapshot) {
      print('Data : ${snapshot.value}');
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Firebase Demo"),
      ),
      body: FutureBuilder(builder: (context, snapshot) {
        if (snapshot.hasError) {
          return Text(snapshot.error.toString());
        } else {
          return Container(
            child: Column(
              children: <Widget>[
                Center(
                    child: ElevatedButton(
                        child: Text("Save to Database"),
                        onPressed: () {
                          addData();
                          printFirebase();
                        })),
              ],
            ),
          );
        }
      }),
    );
  }
}

// @dart=2.9 (because i need to use a non-null friendly widget)
import 'package:racpresence/bddtest.dart';

import 'calendrier.dart';
import 'coursdujour.dart';
import 'parametres.dart';
import 'bddtest.dart';

import 'package:flutter/cupertino.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/material.dart';


void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  Firebase.initializeApp();

  runApp(MyApp());
}

class MyApp extends StatelessWidget {
...
}

class MyHomePage extends StatefulWidget {
  ...
}

class _MyHomePageState extends State<MyHomePage> {
  int _selectedIndex = 0;

  final tabs = [
    ...
  ];

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    ...
  }
}

Answer 1

如果有人问他，我就这样解决

final ref = FirebaseDatabase(databaseURL:
      $(url of my database) )
      .reference()