chat_screen.dart

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

class ChatScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: StreamBuilder(
          stream: Firestore.instance
              .collection('/ChatApp/PuC0dvcVj5P6i1B9Qmns/messages/')
              .snapshots(),
          builder: (ctx, streamSnapshot) {
            print(streamSnapshot.data.documents);
            final documents = streamSnapshot.data.documents;
            return ListView.builder(
              itemBuilder: (ctx, index) =>
                  Container(child: Text('CHAT!'), padding: EdgeInsets.all(8)),
              itemCount: documents.length,
            );
          }),
      floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: () {
            Firestore.instance
                .collection('/ChatApp/PuC0dvcVj5P6i1B9Qmns/messages')
                .snapshots()
                .listen((data) {
              data.documents.forEach((element) {
                print(element['chat']);
              });
            });
          }),
    );
  }
}