Firestore loading is working

lib/database.dart

@@ -8,24 +8,6 @@ final CollectionReference _mainCollection = _firestore.collection('Messages');
 class Database {
   static String? userUid;
 
-  static Future<void> addItem({
-    required String title,
-    required String description,
-  }) async {
-    DocumentReference documentReferencer =
-    _mainCollection.doc(userUid).collection('items').doc();
-
-    Map<String, dynamic> data = <String, dynamic>{
-      "title": title,
-      "description": description,
-    };
-
-    await documentReferencer
-        .set(data)
-        .whenComplete(() => print("Note item added to the database"))
-        .catchError((e) => print(e));
-  }
-
   static Future<void> addNewMail({
     required String mailSender,
     required String mailContent
@@ -60,13 +42,6 @@ class Database {
         .catchError((e) => print(e));
   }
 
-  static Stream<QuerySnapshot> readItems() {
-    CollectionReference notesItemCollection =
-    _mainCollection.doc(userUid).collection('items');
-
-    return notesItemCollection.snapshots();
-  }
-
   static Stream<QuerySnapshot> readAllMails() {
     return _mainCollection.snapshots();
   }

lib/group_chat_view.dart

@@ -0,0 +1,128 @@
+import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:flutter/material.dart';
+
+import 'database.dart';
+
+class GroupChat extends StatelessWidget {
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(
+          '家书：',
+          style: TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
+        ),
+        centerTitle: true,
+      ),
+      body: ChatScreen(),
+    );
+  }
+}
+
+class ChatScreen extends StatelessWidget {
+  const ChatScreen();
+
+  @override
+  Widget build(BuildContext context) {
+    return StreamBuilder<QuerySnapshot>(
+        stream: Database.readAllMails(),
+        builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
+          if (snapshot.hasError) {
+            return Text('Something went wrong');
+          } else if (snapshot.connectionState == ConnectionState.waiting) {
+            return Center(
+              child: CircularProgressIndicator(
+                valueColor: AlwaysStoppedAnimation<Color>(
+                  Colors.orange,
+                ),
+              ),
+            );
+          }
+          return new ListView(
+            children: snapshot.data!.docs.map((DocumentSnapshot document) {
+              Map<String, dynamic> data = document.data() as Map<String,
+                  dynamic>;
+              String name = data['name'];
+              String mail = data['message'];
+              return buildItem(name, mail, "", context);
+            }).toList(),
+            padding: EdgeInsets.all(10.0),
+            physics: BouncingScrollPhysics(),
+          );
+        }
+        );
+  }
+
+  Widget buildItem(
+      String teacherName,
+      String teacherMessage,
+      String teacherAvatar,
+      BuildContext context) {
+    return Container(
+      child: Column(
+        children: <Widget>[
+          Row(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: <Widget>[
+              // Avatar
+              Container(
+                width: 36,
+                height: 36,
+                alignment: Alignment.center,
+                decoration: new BoxDecoration(
+                  image: DecorationImage(
+                      image: AssetImage('assets/rodion-kutsaev.jpeg'),
+                      fit: BoxFit.fill
+                  ),
+                  borderRadius: BorderRadius.all(
+                    Radius.circular(18.0),
+                  ),
+                ),
+                //padding: EdgeInsets.only(top: 50),
+                margin: EdgeInsets.only(top: 5.0),
+              ),
+
+              // Text message
+              Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: <Widget>[
+                  // Name
+                  Container(
+                    child: Text(
+                      teacherName,
+                      style: TextStyle(color: Colors.grey, fontSize: 10.0, fontStyle: FontStyle.italic),
+                    ),
+                    padding: EdgeInsets.only(left: 10.0),
+                  ),
+
+                  SizedBox(height: 1),
+
+                  // Letter
+                  Padding(
+                    padding: EdgeInsets.fromLTRB(5.0, 0.0, 5.0, 5.0),
+                    child: SizedBox(
+                      width: MediaQuery.of(context).size.width * 0.6,
+                      child: Card(
+                        elevation: 8,
+                        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
+                        child: Padding(
+                          padding: EdgeInsets.all(10),
+                          child: Text(
+                            teacherMessage,
+                          ),
+                        ),
+                      ),
+                    ),
+                  ),
+                ],
+              ),
+            ],
+          ),
+
+          SizedBox(height: 7),
+        ],
+      ),
+    );
+  }
+}

lib/mail_view.dart

@@ -1,5 +1,3 @@
-import 'dart:convert';
-
 import 'package:flutter/material.dart';
 import 'package:from_android/database.dart';
 

lib/main.dart

@@ -1,8 +1,6 @@
 import 'package:from_android/home_page.dart';
 import 'package:flutter/material.dart';
 
-import 'chat_view.dart';
-
 void main() => runApp(new MainApp());
 
 class MainApp extends StatelessWidget {

lib/sliding_cards.dart

@@ -5,6 +5,7 @@ import 'dart:math' as math;
 import 'package:from_android/staggered_grid_view.dart';
 
 import 'chat_view.dart';
+import 'group_chat_view.dart';
 
 class SlidingCardsView extends StatefulWidget {
   @override
@@ -185,7 +186,7 @@ class CardContent extends StatelessWidget {
                       Navigator.push(
                           context,
                           MaterialPageRoute(
-                              builder: (context) => Chat()));
+                              builder: (context) => GroupChat()));
                     }
                   },
                 ),