return a stream from querychannels and add channelsBloc to handle channelListview

example/lib/main.dart

@@ -63,17 +63,28 @@ class ChannelListPage extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      body: ChannelListView(
+      body: PageView(
-        filter: {
+        children: <Widget>[
-          'members': {
+          ChannelListView(
-            '\$in': [StreamChat.of(context).user.id],
+            filter: {
-          }
+              'members': {
-        },
+                '\$in': [StreamChat.of(context).user.id],
-        sort: [SortOption('last_message_at')],
+              }
-        pagination: PaginationParams(
+            },
-          limit: 20,
+            sort: [SortOption('last_message_at')],
-        ),
+            pagination: PaginationParams(
-        channelWidget: ChannelPage(),
+              limit: 20,
+            ),
+            channelWidget: ChannelPage(),
+          ),
+          ChannelListView(
+            sort: [SortOption('last_message_at')],
+            pagination: PaginationParams(
+              limit: 20,
+            ),
+            channelWidget: ChannelPage(),
+          ),
+        ],
       ),
     );
   }

lib/src/channel_list_view.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:stream_chat/stream_chat.dart';
+import 'package:stream_chat_flutter/src/channels_bloc.dart';
 
 import '../stream_chat_flutter.dart';
 import 'channel_preview.dart';
@@ -99,15 +100,16 @@ class ChannelListView extends StatefulWidget {
 }
 
 class _ChannelListViewState extends State<ChannelListView>
-    with WidgetsBindingObserver {
+    with WidgetsBindingObserver, AutomaticKeepAliveClientMixin {
   final ScrollController _scrollController = ScrollController();
+  ChannelsBloc channelsBloc;
 
   @override
   Widget build(BuildContext context) {
-    final streamChat = StreamChat.of(context);
+    super.build(context);
     return RefreshIndicator(
       onRefresh: () async {
-        return streamChat.queryChannels(
+        return channelsBloc.queryChannels(
           filter: widget.filter,
           sortOptions: widget.sort,
           paginationParams: widget.pagination,
@@ -115,7 +117,7 @@ class _ChannelListViewState extends State<ChannelListView>
         );
       },
       child: StreamBuilder<List<Channel>>(
-          stream: streamChat.channelsStream,
+          stream: channelsBloc.channelsStream,
           builder: (context, snapshot) {
             if (snapshot.hasError) {
               if (snapshot.error is Error) {
@@ -163,7 +165,7 @@ class _ChannelListViewState extends State<ChannelListView>
                     ),
                     FlatButton(
                       onPressed: () {
-                        streamChat.queryChannels(
+                        channelsBloc.queryChannels(
                           filter: widget.filter,
                           sortOptions: widget.sort,
                           paginationParams: widget.pagination,
@@ -215,7 +217,7 @@ class _ChannelListViewState extends State<ChannelListView>
     if (i < channels.length) {
       final channel = channels[i];
 
-      final channelClient = streamChat.channels.firstWhere(
+      final channelClient = channelsBloc.channels.firstWhere(
         (c) => c.cid == channel.cid,
         orElse: () => null,
       );
@@ -285,7 +287,7 @@ class _ChannelListViewState extends State<ChannelListView>
 
   Widget _buildQueryProgressIndicator(context, StreamChatState streamChat) {
     return StreamBuilder<bool>(
-        stream: streamChat.queryChannelsLoading,
+        stream: channelsBloc.queryChannelsLoading,
         initialData: false,
         builder: (context, snapshot) {
           if (snapshot.hasError) {
@@ -320,11 +322,11 @@ class _ChannelListViewState extends State<ChannelListView>
   void _listenChannelPagination(StreamChatState streamChat) {
     if (_scrollController.position.maxScrollExtent ==
         _scrollController.offset) {
-      streamChat.queryChannels(
+      channelsBloc.queryChannels(
         filter: widget.filter,
         sortOptions: widget.sort,
         paginationParams: widget.pagination.copyWith(
-          offset: streamChat.channels.length,
+          offset: channelsBloc.channels.length,
         ),
         options: widget.options,
       );
@@ -334,11 +336,12 @@ class _ChannelListViewState extends State<ChannelListView>
   @override
   void initState() {
     super.initState();
+    final streamChat = StreamChat.of(context);
 
+    channelsBloc = ChannelsBloc(streamChat.client);
     WidgetsBinding.instance.addObserver(this);
 
-    final streamChat = StreamChat.of(context);
+    channelsBloc.queryChannels(
-    streamChat.queryChannels(
       filter: widget.filter,
       sortOptions: widget.sort,
       paginationParams: widget.pagination,
@@ -353,7 +356,7 @@ class _ChannelListViewState extends State<ChannelListView>
   @override
   void didChangeAppLifecycleState(AppLifecycleState state) {
     if (state == AppLifecycleState.resumed) {
-      StreamChat.of(context).queryChannels(
+      channelsBloc.queryChannels(
         filter: widget.filter,
         sortOptions: widget.sort,
         paginationParams: widget.pagination,
@@ -366,6 +369,10 @@ class _ChannelListViewState extends State<ChannelListView>
   @override
   void dispose() {
     WidgetsBinding.instance.removeObserver(this);
+    channelsBloc.dispose();
     super.dispose();
   }
+
+  @override
+  bool get wantKeepAlive => true;
 }

lib/src/channels_bloc.dart

@@ -0,0 +1,72 @@
+import 'package:rxdart/rxdart.dart';
+import 'package:stream_chat/stream_chat.dart';
+
+class ChannelsBloc {
+  final Client client;
+
+  ChannelsBloc(this.client);
+
+  /// The current channel list
+  List<Channel> get channels => _channelsController.value;
+
+  /// The current channel list as a stream
+  Stream<List<Channel>> get channelsStream => _channelsController.stream;
+
+  final BehaviorSubject<bool> _queryChannelsLoadingController =
+      BehaviorSubject.seeded(false);
+
+  final BehaviorSubject<List<Channel>> _channelsController =
+      BehaviorSubject.seeded([]);
+
+  /// The stream notifying the state of queryChannel call
+  Stream<bool> get queryChannelsLoading =>
+      _queryChannelsLoadingController.stream;
+
+  /// Calls [client.queryChannels] updating [queryChannelsLoading] stream
+  Future<void> queryChannels({
+    Map<String, dynamic> filter,
+    List<SortOption> sortOptions,
+    PaginationParams paginationParams,
+    Map<String, dynamic> options,
+    bool onlyOffline = false,
+  }) async {
+    if (_queryChannelsLoadingController.value == true) {
+      return;
+    }
+    _queryChannelsLoadingController.sink.add(true);
+
+    try {
+      final clear = paginationParams == null ||
+          paginationParams.offset == null ||
+          paginationParams.offset == 0;
+      final oldChannels = List<Channel>.from(channels);
+      client
+          .queryChannels(
+        filter: filter,
+        sort: sortOptions,
+        options: options,
+        paginationParams: paginationParams,
+        onlyOffline: onlyOffline,
+      )
+          .listen((channels) {
+        if (clear) {
+          _channelsController.add(channels);
+        } else {
+          final l = oldChannels + channels;
+          _channelsController.add(l);
+        }
+      }, onDone: () {
+        _queryChannelsLoadingController.sink.add(false);
+      }, onError: (err, stackTrace) {
+        _queryChannelsLoadingController.addError(err, stackTrace);
+      });
+    } catch (err, stackTrace) {
+      _queryChannelsLoadingController.addError(err, stackTrace);
+    }
+  }
+
+  void dispose() {
+    _channelsController.close();
+    _queryChannelsLoadingController.close();
+  }
+}

lib/src/stream_chat.dart

@@ -2,7 +2,6 @@ import 'dart:async';
 
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
-import 'package:rxdart/rxdart.dart';
 import 'package:stream_chat/stream_chat.dart';
 import 'package:stream_chat_flutter/src/stream_chat_theme.dart';
 
@@ -59,15 +58,12 @@ class StreamChat extends StatefulWidget {
   }
 }
 
-class StreamChatState extends State<StreamChat>
+class StreamChatState extends State<StreamChat> with WidgetsBindingObserver {
-    with WidgetsBindingObserver, AutomaticKeepAliveClientMixin {
-  final List<StreamSubscription> _subscriptions = [];
   Client get client => widget.client;
   final GlobalKey<NavigatorState> _navigatorKey = GlobalKey<NavigatorState>();
 
   @override
   Widget build(BuildContext context) {
-    super.build(context);
     final theme = _getTheme(context, widget.streamChatThemeData);
     return StreamChatTheme(
       data: theme,
@@ -179,46 +175,6 @@ class StreamChatState extends State<StreamChat>
   /// The current user as a stream
   Stream<User> get userStream => widget.client.state.userStream;
 
-  /// The current channel list
-  List<Channel> get channels => client.state.channels;
-
-  /// The current channel list as a stream
-  Stream<List<Channel>> get channelsStream => client.state.channelsStream;
-
-  final BehaviorSubject<bool> _queryChannelsLoadingController =
-      BehaviorSubject.seeded(false);
-
-  /// The stream notifying the state of queryChannel call
-  Stream<bool> get queryChannelsLoading =>
-      _queryChannelsLoadingController.stream;
-
-  /// Calls [client.queryChannels] updating [queryChannelsLoading] stream
-  Future<void> queryChannels({
-    Map<String, dynamic> filter,
-    List<SortOption> sortOptions,
-    PaginationParams paginationParams,
-    Map<String, dynamic> options,
-    bool onlyOffline = false,
-  }) async {
-    if (_queryChannelsLoadingController.value == true) {
-      return;
-    }
-    _queryChannelsLoadingController.sink.add(true);
-
-    try {
-      await widget.client.queryChannels(
-        filter: filter,
-        sort: sortOptions,
-        options: options,
-        paginationParams: paginationParams,
-        onlyOffline: onlyOffline,
-      );
-      _queryChannelsLoadingController.sink.add(false);
-    } catch (err, stackTrace) {
-      _queryChannelsLoadingController.addError(err, stackTrace);
-    }
-  }
-
   @override
   void initState() {
     super.initState();
@@ -239,12 +195,7 @@ class StreamChatState extends State<StreamChat>
 
   @override
   void dispose() {
-    _subscriptions.forEach((s) => s.cancel());
-    _queryChannelsLoadingController.close();
     WidgetsBinding.instance.removeObserver(this);
     super.dispose();
   }
-
-  @override
-  bool get wantKeepAlive => true;
 }

pubspec.yaml

@@ -17,7 +17,7 @@ dependencies:
   url_launcher: ^5.4.2
   video_player: ^0.10.8+1
   chewie: ^0.9.10
-  file_picker: ^1.5.1
+  file_picker: ^1.6.0
   image_picker: ^0.6.4
   flutter_keyboard_visibility: ^0.7.0
   stream_chat: