refactor!(core): Refactor BetterStreamBuilder.

1. BREAKING: Renamed `BetterStreamBuilder.loadingBuilder` to `.noDataBuilder`.
2. BREAKING: Added non-null constraint on `BetterStreamBuilder<T extends Object>`.
3. `BetterStreamBuilder.initialData` is now nullable/not-required.

Signed-off-by: xsahil03x <[email protected]>

packages/stream_chat_flutter_core/CHANGELOG.md

@@ -1,5 +1,11 @@
 ## Upcoming
 
+🛑️ Breaking Changes from `2.1.1`
+- Renamed `BetterStreamBuilder.loadingBuilder` to `.noDataBuilder`
+
+🔄 Changed
+- `BetterStreamBuilder.initialData` is now nullable/not-required.
+
 🐞 Fixed
 - [#612](https://github.com/GetStream/stream-chat-flutter/issues/612) `ChannelListView` pagination doesn't work after refresh
 

packages/stream_chat_flutter_core/lib/src/better_stream_builder.dart

@@ -6,23 +6,23 @@ import 'package:flutter/widgets.dart';
 /// It requires [initialData] and will rebuild
 /// only when the new data is different than the current data
 /// The [comparator] is used to check if the new data is different
-class BetterStreamBuilder<T> extends StatefulWidget {
+class BetterStreamBuilder<T extends Object> extends StatefulWidget {
   /// Creates a new BetterStreamBuilder
   const BetterStreamBuilder({
     required this.stream,
-    required this.initialData,
     required this.builder,
-    this.loadingBuilder,
+    this.initialData,
+    this.noDataBuilder,
     this.errorBuilder,
     this.comparator,
     Key? key,
   }) : super(key: key);
 
   /// The stream to listen to
-  final Stream<T>? stream;
+  final Stream<T?>? stream;
 
   /// The initial data available
-  final T initialData;
+  final T? initialData;
 
   /// Comparator used to check if the new data is different than the last one
   final bool Function(T?, T?)? comparator;
@@ -31,7 +31,7 @@ class BetterStreamBuilder<T> extends StatefulWidget {
   final Widget Function(BuildContext context, T data) builder;
 
   /// Builder that builds when the data is null
-  final Widget Function(BuildContext context)? loadingBuilder;
+  final Widget Function(BuildContext context)? noDataBuilder;
 
   /// Builder used when there is an error
   final Widget Function(BuildContext context, Object error)? errorBuilder;
@@ -40,21 +40,26 @@ class BetterStreamBuilder<T> extends StatefulWidget {
   _BetterStreamBuilderState createState() => _BetterStreamBuilderState<T>();
 }
 
-class _BetterStreamBuilderState<T> extends State<BetterStreamBuilder<T>> {
+class _BetterStreamBuilderState<T extends Object>
+    extends State<BetterStreamBuilder<T>> {
   T? _lastEvent;
-  StreamSubscription? _subscription;
+  StreamSubscription<T?>? _subscription;
   Object? _lastError;
 
   @override
   Widget build(BuildContext context) {
-    if (_lastError != null) {
+    final error = _lastError;
-      return widget.errorBuilder!(context, _lastError!);
+    if (error != null) {
+      final errorBuilder = widget.errorBuilder;
+      if (errorBuilder != null) {
+        return errorBuilder(context, error);
+      }
     }
-
+    final event = _lastEvent;
-    if (_lastEvent == null) {
+    if (event == null) {
-      return widget.loadingBuilder?.call(context) ?? const Offstage();
+      return widget.noDataBuilder?.call(context) ?? const Offstage();
     }
-    return widget.builder(context, _lastEvent ?? widget.initialData);
+    return widget.builder(context, event);
   }
 
   @override
@@ -87,22 +92,22 @@ class _BetterStreamBuilderState<T> extends State<BetterStreamBuilder<T>> {
 
   void _onError(error) {
     if (widget.errorBuilder != null && error != _lastError) {
+      _lastError = error;
       if (mounted) {
         setState(() {});
       }
-      _lastError = error;
     }
   }
 
-  void _onEvent(T event) {
+  void _onEvent(T? event) {
     _lastError = null;
     final isEqual =
         widget.comparator?.call(_lastEvent, event) ?? event == _lastEvent;
     if (!isEqual) {
+      _lastEvent = event;
       if (mounted) {
         setState(() {});
       }
-      _lastEvent = event;
     }
   }
 }

packages/stream_chat_flutter_core/lib/src/channel_list_core.dart

@@ -4,6 +4,7 @@ import 'dart:convert';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:stream_chat/stream_chat.dart';
+import 'package:stream_chat_flutter_core/src/better_stream_builder.dart';
 import 'package:stream_chat_flutter_core/src/channels_bloc.dart';
 import 'package:stream_chat_flutter_core/src/stream_chat_core.dart';
 import 'package:stream_chat_flutter_core/src/typedef.dart';
@@ -137,19 +138,14 @@ class ChannelListCoreState extends State<ChannelListCore> {
   @override
   Widget build(BuildContext context) => _buildListView(_channelsBloc);
 
-  StreamBuilder<List<Channel>> _buildListView(
+  BetterStreamBuilder<List<Channel>> _buildListView(
     ChannelsBlocState channelsBlocState,
   ) =>
-      StreamBuilder<List<Channel>>(
+      BetterStreamBuilder<List<Channel>>(
         stream: channelsBlocState.channelsStream,
-        builder: (context, snapshot) {
+        errorBuilder: widget.errorBuilder,
-          if (snapshot.hasError) {
+        noDataBuilder: widget.loadingBuilder,
-            return widget.errorBuilder(context, snapshot.error!);
+        builder: (context, channels) {
-          }
-          if (!snapshot.hasData) {
-            return widget.loadingBuilder(context);
-          }
-          final channels = snapshot.data!;
           if (channels.isEmpty) {
             return widget.emptyBuilder(context);
           }

packages/stream_chat_flutter_core/lib/src/message_list_core.dart

@@ -138,7 +138,7 @@ class MessageListCoreState extends State<MessageListCore> {
       return true;
     }
 
-    return BetterStreamBuilder<List<Message>?>(
+    return BetterStreamBuilder<List<Message>>(
       initialData: initialData,
       comparator: const ListEquality().equals,
       stream: messagesStream!.map(
@@ -148,9 +148,9 @@ class MessageListCoreState extends State<MessageListCore> {
                 ),
       ),
       errorBuilder: widget.errorBuilder,
-      loadingBuilder: widget.loadingBuilder,
+      noDataBuilder: widget.loadingBuilder,
       builder: (context, data) {
-        final messageList = data?.reversed.toList(growable: false) ?? [];
+        final messageList = data.reversed.toList(growable: false);
         if (messageList.isEmpty && !_isThreadConversation) {
           if (_upToDate) {
             return widget.emptyBuilder(context);

packages/stream_chat_flutter_core/lib/src/message_search_list_core.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:stream_chat/stream_chat.dart';
+import 'package:stream_chat_flutter_core/src/better_stream_builder.dart';
 import 'package:stream_chat_flutter_core/src/message_search_bloc.dart';
 import 'package:stream_chat_flutter_core/src/typedef.dart';
 
@@ -132,16 +133,11 @@ class MessageSearchListCoreState extends State<MessageSearchListCore> {
   Widget build(BuildContext context) => _buildListView(_messageSearchBloc!);
 
   Widget _buildListView(MessageSearchBlocState messageSearchBloc) =>
-      StreamBuilder<List<GetMessageResponse>>(
+      BetterStreamBuilder<List<GetMessageResponse>>(
         stream: messageSearchBloc.messagesStream,
-        builder: (context, snapshot) {
+        errorBuilder: widget.errorBuilder,
-          if (snapshot.hasError) {
+        noDataBuilder: widget.loadingBuilder,
-            return widget.errorBuilder(context, snapshot.error!);
+        builder: (context, items) {
-          }
-          if (!snapshot.hasData) {
-            return widget.loadingBuilder(context);
-          }
-          final items = snapshot.data!;
           if (items.isEmpty) {
             return widget.emptyBuilder(context);
           }

packages/stream_chat_flutter_core/lib/src/user_list_core.dart

@@ -176,16 +176,11 @@ class UserListCoreState extends State<UserListCore>
         },
       );
 
-  StreamBuilder<List<ListItem>> _buildListView() => StreamBuilder(
+  BetterStreamBuilder<List<ListItem>> _buildListView() => BetterStreamBuilder(
         stream: _buildUserStream(),
-        builder: (context, snapshot) {
+        errorBuilder: widget.errorBuilder,
-          if (snapshot.hasError) {
+        noDataBuilder: widget.loadingBuilder,
-            return widget.errorBuilder(context, snapshot.error!);
+        builder: (context, items) {
-          }
-          if (!snapshot.hasData) {
-            return widget.loadingBuilder(context);
-          }
-          final items = snapshot.data!;
           if (items.isEmpty) {
             return widget.emptyBuilder(context);
           }