CometChat Flutter UIKit — Conversations

The CometChatConversations widget displays a list of recent conversations with real-time updates.

Basic Usage

CometChatConversations(
  onItemTap: (conversation) {
    final user = conversation.conversationWith is User
        ? conversation.conversationWith as User : null;
    final group = conversation.conversationWith is Group
        ? conversation.conversationWith as Group : null;
    Navigator.push(context, MaterialPageRoute(
      builder: (_) => MessagesScreen(user: user, group: group),
    ));
  },
)

Architecture

conversations/
├── bloc/
│   ├── conversations_bloc.dart    # SDK listeners, real-time updates, O(1) lookups
│   ├── conversations_event.dart   # LoadConversations, DeleteConversation, etc.
│   └── conversations_state.dart   # ConversationsInitial/Loading/Loaded/Empty/Error
├── domain/usecases/               # GetConversationsUseCase, DeleteConversationUseCase, etc.
├── data/                          # Repository + DataSources (remote + local)
├── di/                            # ConversationsServiceLocator (singleton)
└── widgets/                       # List item, subtitle, trailing, empty/error/loading views

State Classes

ConversationsInitial    // Before any data loaded
ConversationsLoading    // Fetching initial list
ConversationsLoaded     // Has data: conversations, hasMore, selectedConversations, isLoadingMore
ConversationsEmpty      // No conversations exist
ConversationsError      // Error with message + optional previousConversations

ConversationsLoaded uses a monotonically increasing _version counter to guarantee unique emissions even when conversation IDs haven't changed (SDK's Conversation.== only compares conversationId).

Key Events

Event	Purpose
LoadConversations({silent})	Initial load. silent: true keeps existing list visible during refresh.
LoadMoreConversations	Pagination (scroll to bottom)
DeleteConversation(id)	Calls SDK to delete
RemoveConversation(id)	Remove from list without SDK call (e.g., after group kick)
SetActiveConversation(id)	Track which conversation is open
UpdateConversation(id, conversation)	Update a specific conversation's data
ResetUnreadCount(id)	Clear unread badge when user reads messages

Real-Time Features

The BLoC automatically registers SDK listeners for:

• New messages → updates last message + moves conversation to top
• Typing indicators → per-conversation ValueNotifier<List<TypingIndicator>>
• User presence → online/offline status
• Read/delivery receipts → receipt icons
• Group events → member join/leave/kick/ban
• Connection state → reconnect triggers silent refresh

Typing Indicators (ValueNotifier Pattern)

// In your custom list item, use ValueListenableBuilder for isolated rebuilds:
ValueListenableBuilder<List<TypingIndicator>>(
  valueListenable: conversationsBloc.getTypingNotifier(conversation.conversationId!),
  builder: (context, typingList, child) {
    if (typingList.isEmpty) return _buildLastMessage();
    return Text('${typingList.first.sender?.name} is typing...');
  },
)

Customization — View Slots

CometChatConversations(
  // Replace entire list item
  listItemView: (conversation) => MyCustomListItem(conversation),

  // Replace just the subtitle — two-arg builder (BuildContext, Conversation)
  subtitleView: (context, conversation) => Text(conversation.lastMessage?.text ?? ''),

  // Replace trailing (time + badge) — SINGLE-arg builder. Note the asymmetry:
  // subtitleView/leadingView/titleView take (BuildContext, Conversation),
  // but trailingView takes just (Conversation).
  trailingView: (conversation) => MyTrailingWidget(conversation),

  // Style overrides
  conversationsStyle: CometChatConversationsStyle(
    backgroundColor: colors.background1,
    titleStyle: typography.heading3?.bold,
  ),

  // Configuration
  usersStatusVisibility: true,
  receiptsVisibility: true,
  deleteConversationOptionVisibility: true,
  hideAppbar: false,
  showBackButton: false,

  // Text formatters for subtitle preview
  textFormatters: [
    CometChatMentionsFormatter(),
    MarkdownTextFormatter(),
  ],
)

Custom ConversationsRequest

CometChatConversations(
  conversationsRequestBuilder: ConversationsRequestBuilder()
    ..limit = 30
    ..conversationType = 'user'  // Only 1:1 chats
    ..withTags = true
    ..tags = ['important'],
)

Gotchas

• ConversationsLoaded uses a _version counter because SDK's Conversation.== only compares conversationId. Without it, BLoC considers two lists with same IDs as equal even when lastMessage or unreadMessageCount changed, and skips the emission.
• The BLoC uses _conversationIndexMap for O(1) lookups. If you maintain your own list outside the BLoC, keep a parallel Map for performance.
• silent: true on LoadConversations keeps the existing list visible during refresh — use this for background→foreground and reconnect scenarios, not initial load.
• Typing indicators use ValueNotifier per conversation, NOT BLoC state. This prevents the entire list from rebuilding when one person types.

Anti-Patterns

// ❌ WRONG — navigating with raw conversation object
onItemTap: (conv) => Navigator.push(context, MaterialPageRoute(
  builder: (_) => MessagesScreen(conversation: conv), // MessagesScreen expects user OR group
))

// ✅ CORRECT — extract user/group from conversation
onItemTap: (conv) {
  final user = conv.conversationWith is User ? conv.conversationWith as User : null;
  final group = conv.conversationWith is Group ? conv.conversationWith as Group : null;
  Navigator.push(context, MaterialPageRoute(
    builder: (_) => MessagesScreen(user: user, group: group),
  ));
}

// ❌ WRONG — creating BLoC without initializing ServiceLocator
final bloc = ConversationsBloc(/* ... */);

// ✅ CORRECT — setup first (widget does this automatically)
ConversationsServiceLocator.instance.setup();
final bloc = ConversationsBloc(
  getLoggedInUserUseCase: ConversationsServiceLocator.instance.getLoggedInUserUseCase,
  getConversationUseCase: ConversationsServiceLocator.instance.getConversationUseCase,
  markAsDeliveredUseCase: ConversationsServiceLocator.instance.markAsDeliveredUseCase,
  deleteConversationUseCase: ConversationsServiceLocator.instance.deleteConversationUseCase,
);

// ❌ WRONG — rebuilding entire list for typing indicator
BlocBuilder<ConversationsBloc, ConversationsState>(
  builder: (context, state) {
    // This rebuilds ALL items when ANY state changes
  },
)

// ✅ CORRECT — use ValueListenableBuilder per item
ValueListenableBuilder<List<TypingIndicator>>(
  valueListenable: bloc.getTypingNotifier(conversationId),
  builder: (_, typingList, __) { /* Only this item rebuilds */ },
)

Checklist

• onItemTap extracts User/Group from conversation.conversationWith
• subscriptionType set in UIKitSettings (required for real-time updates)
• Typing indicators use ValueListenableBuilder, not BLoC state
• Custom list items use CometChatThemeHelper for colors
• Text formatters passed if using mentions or markdown in subtitle preview
• deleteConversationOptionVisibility set based on app requirements