Flutter streambuilder 不会更新 statefulwidget 或 statelesswidget

Question

我正在尝试构建一个流生成器。
我的问题是streambuilder没有更新streambuilder小部件内的其他statefulWidgets。

这是我的代码：

class ChatPage extends StatefulWidget {
  //pass parm
  var chat_object;
  ChatPage(this.chat_object, {Key? key}) : super(key: key);

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

class _ChatPage extends State<ChatPage> {
  //pass parm
  var chat_object;
  _ChatPage(this.chat_object);

  @override
  Widget build(BuildContext context) {
    // Full screen width and height
    double width = MediaQuery.of(context).size.width;
    double height = MediaQuery.of(context).size.height;

    // Height (without SafeArea)
    var padding = MediaQuery.of(context).padding;
    double height1 = height - padding.top - padding.bottom;

    // Height (without status bar)
    double height2 = height - padding.top;

    // Height (without status and toolbar)
    double height3 = height - padding.top - kToolbarHeight;

    //scaffold
    return Scaffold(
      appBar: customAppBarGoBack('Chat', context),
      body: LimitedBox(
        maxHeight: height3,
        child: Stack(
          children: [
            StreamBuilder<dynamic>(
              stream: FirebaseFirestore.instance
                  .collection('chat')
                  .doc('chat_messages')
                  .collection(chat_object.chat_message_id[0].trim())
                  .orderBy('message_time')
                  .snapshots(),
              builder: (
                BuildContext context,
                AsyncSnapshot<dynamic> snapshot,
              ) {
                if (snapshot.connectionState == ConnectionState.waiting) {
                  return CircularProgressIndicator();
                } else {
                  if (snapshot.hasError) {
                    return const Text('Error');
                  } else if (snapshot.hasData) {
                    //chat room object list
                    var chat_room_object =
                        load_object(snapshot.data, chat_object).first;

                    //chat message object list
                    var message_object =
                        load_object(snapshot.data, chat_object).last;

                    print('message_object: ' + message_object.toString());

                    return Test(chat_room_object, message_object);
                  } else {
                    return const Text('Empty data');
                  }
                }
              },
            ),
          ],
        ),
      ),
      drawer: CustomSideBar(context),
    );
  }
}

//test
class Test extends StatefulWidget {
  //pass parm
  var chat_room_object;
  var message_object;
  Test(this.chat_room_object, this.message_object, {Key? key})
      : super(key: key);

  @override
  _Test createState() => _Test(chat_room_object, message_object);
}

class _Test extends State<Test> {
  //pass parm
  _Test(this.chat_room_object, this.message_object);
  var chat_room_object;
  var message_object;

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: message_object.length,
      itemBuilder: (context, i) {
        return Text(message_object[i].message.toString());
      },
    );
  }
}

如果我在流构建器中构建一个列表，该列表将被更新。 但是，如果我在新小部件内构建列表并将值传递给列表小部件，则该小部件将不会更新。

任何人都可以给我一个简单示例如何更新包含在流构建器中的 statefulwidget 中的值？

Answer 1

除了在Test小部件的状态构造函数中传递参数，您可以尝试直接从小部件中访问它们吗？示例如下。

//test
class Test extends StatefulWidget {
//pass parm
var chat_room_object;
var message_object;

Test(this.chat_room_object, this.message_object, {Key? key})
  : super(key: key);

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

class _Test extends State<Test> {
//pass parm
_Test();

@override
Widget build(BuildContext context) {
return ListView.builder(
  itemCount: widget.message_object.length,
  itemBuilder: (context, i) {
    return Text(widget.message_object[i].message.toString());
  },
);
}
}