Firebase 数据库未在 flutter 应用程序中更新

Question

I am working on a chatting app. I have done all the processes to install firebase and my app is working fine. But when I connected the firebase database and tried to store the messages into the database. The database does not update with the new document(message and user email).

This is my code -

this is how my firebase database page looks like

this is how my app looks like

import 'package:flutter/material.dart';
import 'package:flash_chat/constants.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:cloud_firestore/cloud_firestore.dart';

class ChatScreen extends StatefulWidget {
  static const String id = 'chat_screen';

  @override _ChatScreenState createState() => _ChatScreenState();
}

class _ChatScreenState extends State<ChatScreen> {
  final _firestore = Firestore.instance;
  String messageText;
  final _auth = FirebaseAuth.instance;
  FirebaseUser loggedinUser;

  void getCurrentUser() async {
    try {
      final user = await _auth.currentUser();
      if (user != null) {
        loggedinUser = user;
        print(user.email);
      }
    } catch (e) {
      print(e);
    }
  }

  @override Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: null,
        actions: <Widget>[
          IconButton(
              icon: Icon(Icons.close),
              onPressed: () {
                _auth.signOut();
                Navigator.pop(context);
                //Implement logout functionality
              }),
        ],
        title: Text('⚡️Chat'),
        backgroundColor: Colors.lightBlueAccent,
      ),
      body: SafeArea(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            Container(
              decoration: kMessageContainerDecoration,
              child: Row(
                crossAxisAlignment: CrossAxisAlignment.center,
                children: <Widget>[
                  Expanded(
                    child: TextField(
                      onChanged: (value) {
                        messageText = value;
                        //Do something with the user input.
                      },
                      decoration: kMessageTextFieldDecoration,
                    ),
                  ),
                  FlatButton(
                    onPressed: () {
                      _firestore.collection('messages').add({
                        'sender': loggedinUser.email,
                        'text': messageText,
                      });
                      //Implement send functionality.
                    },
                    child: Text(
                      'Send',
                      style: kSendButtonTextStyle,
                    ),
                  ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}

**

Answer 1

It seems that the problem is you're trying to add data with null values, and that's why you don't see any changes.

The values that seems to be null are loggedinUser.email and messageText , check if the user has an email and for the messageText , in onChanged you should do messageText = value; inside a setState() , but instead of doing that you could add a controller to the TextField and then use controller.text .