flutter - 我正在练习一个消息应用程序。我把它存放在壁炉

Question

我正在开发一个Flutter应用程序，并将文本内部消息存储在FIRESTORE中。但是这里的问题是，当我键入一条消息并按onTap时，它将消息存储在Firestore中，但是streambuilder不会按时间顺序更新文本。这怎么办？
这是消息更新

 Expanded(
                child: Container(
                  child: Column(
                    children: [
                      MessageStream(),
                    ],
                  ),
                ),
              ),

onTap函数在Firestore中添加文本

GestureDetector(
                      onTap: () {
                        _messageTextController.clear();
                        if (messageTyped.trim().isNotEmpty) {
                          _firestore.collection('messages').add({
                            'Text': messageTyped,
                            'Sender': loggedInUser.email,
                          });
                        }
                      },
                      child: Container(
                        margin: EdgeInsets.only(
                            left: 2.2 * SizeConfig.widthMultiplier), //8
                        width: 13.88 * SizeConfig.widthMultiplier,
                        height: 7.44 * SizeConfig.heightMultiplier,
                        decoration: BoxDecoration(
                          shape: BoxShape.circle,
                          color: Colors.lightBlueAccent,
                        ),
                        child: Icon(
                          Icons.send,
                          color: Colors.white,
                        ),
                      ),
                    ),

MessageStream STL小部件

class MessageStream extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder<QuerySnapshot>(
      stream: _firestore.collection('messages').snapshots(),
      builder: (context, snapshot) {
        if (!snapshot.hasData) {
          return Center(
            child: CircularProgressIndicator(
              backgroundColor: Colors.lightBlueAccent,
            ),
          );
        }
        final messages = snapshot.data.docs.reversed;
        List<MessageBubble> messageBubbles = [];
        for (var message in messages) {
          final messageSender = message.data()['Sender'];
          final messageText = message.data()['Text'];
          final currentUser = loggedInUser.email;

          final messageBubble = MessageBubble(
            text: messageText,
            sender: messageSender,
            isMe: currentUser == messageSender,
          );
          messageBubbles.add(messageBubble);
        }
        return Expanded(
          child: ListView(
            reverse: true,
            padding: EdgeInsets.all(10.0),
            children: messageBubbles,
          ),
        );
      },
    );
  }
}

Answer 1

保存消息时添加dateCreated字段:

_firestore.collection('messages').add({
  'Text': messageTyped,
  'Sender': loggedInUser.email,
  'dateCreated': FieldValue.serverTimestamp(),
});

然后使用 dateCreated对流结果进行排序:

StreamBuilder<QuerySnapshot>(
  stream: _firestore.collection('messages')
   .orderBy('dateCreated', descending: false)
   .snapshots(),
  builder: (context, snapshot) {
   ...
 },
)