ViewModel & Data

Access and configure the ViewModel layer to customize data fetching, filtering, and state management.

Each component’s ViewModel manages data fetching, state transitions, and business logic via LiveData. You can access it to configure request parameters, observe state changes, or manipulate the data list directly.

Accessing the ViewModel

Kotlin

val conversations = CometChatConversations(context)
val viewModel: ConversationsViewModel = conversations.getViewModel()

Java

CometChatConversations conversations = new CometChatConversations(context);
ConversationsViewModel viewModel = conversations.getViewModel();

Configuring Data Fetching with RequestBuilders

Use setConversationsRequestBuilder to control what data the component fetches. The builder accepts SDK parameters like limits, tags, and filters.

Kotlin

// Filter conversations by tags and limit to 20 results
val builder = ConversationsRequest.ConversationsRequestBuilder()
    .setLimit(20)
    .setTags(listOf("important", "pinned"))
    .withTags(true)

conversations.setConversationsRequestBuilder(builder)

Java

// Filter conversations by tags and limit to 20 results
ConversationsRequest.ConversationsRequestBuilder builder =
    new ConversationsRequest.ConversationsRequestBuilder()
        .setLimit(20)
        .setTags(Arrays.asList("important", "pinned"))
        .withTags(true);

conversations.setConversationsRequestBuilder(builder);

Pass the builder object, not the result of .build(). The component calls .build() internally.

LiveData Observables

The ViewModel exposes LiveData observables you can observe for custom logic:

Observable	Type	Description
getMutableConversationList()	MutableLiveData<List<Conversation>>	The current list of conversations
getStates()	MutableLiveData<UIKitConstants.States>	Component state (LOADING, LOADED, EMPTY, ERROR)
insertAtTop()	MutableLiveData<Integer>	Emits the index when a new conversation is inserted at the top
moveToTop()	MutableLiveData<Integer>	Emits the index when a conversation moves to the top
updateConversation()	MutableLiveData<Integer>	Emits the index when a conversation is updated
remove()	MutableLiveData<Integer>	Emits the index when a conversation is removed
progressState()	MutableLiveData<UIKitConstants.DeleteState>	Tracks delete operation progress
playSound()	MutableLiveData<Boolean>	Triggers when a new message sound should play
getCometChatException()	MutableLiveData<CometChatException>	Emits errors from the SDK

Kotlin

val viewModel = conversations.getViewModel()

// Observe state changes
viewModel.getStates().observe(lifecycleOwner) { state ->
    when (state) {
        UIKitConstants.States.LOADING -> { /* show custom loading */ }
        UIKitConstants.States.LOADED -> { /* data ready */ }
        UIKitConstants.States.EMPTY -> { /* no conversations */ }
        UIKitConstants.States.ERROR -> { /* handle error */ }
    }
}

// Observe the conversation list
viewModel.getMutableConversationList().observe(lifecycleOwner) { list ->
    // React to list changes
}

Java

ConversationsViewModel viewModel = conversations.getViewModel();

// Observe state changes
viewModel.getStates().observe(lifecycleOwner, state -> {
    if (state == UIKitConstants.States.LOADING) {
        // show custom loading
    } else if (state == UIKitConstants.States.LOADED) {
        // data ready
    }
});

// Observe the conversation list
viewModel.getMutableConversationList().observe(lifecycleOwner, list -> {
    // React to list changes
});

Mutation Methods

The ViewModel provides methods to programmatically manipulate the data list:

Method	Description
addList(List<Conversation>)	Append a list of conversations
remove(Conversation)	Remove a specific conversation
remove(int index)	Remove a conversation by index
update(Conversation, boolean)	Update a conversation in the list
refreshList()	Clear and re-fetch from the server
clear()	Clear all conversations from the list
fetchConversation()	Fetch the next page of conversations
deleteConversation(Conversation)	Delete a conversation via the SDK

Kotlin

val viewModel = conversations.getViewModel()

// Refresh the entire list
viewModel.refreshList()

// Remove a specific conversation
viewModel.remove(conversation)

// Clear all data
viewModel.clear()

Java

ConversationsViewModel viewModel = conversations.getViewModel();

// Refresh the entire list
viewModel.refreshList();

// Remove a specific conversation
viewModel.remove(conversation);

// Clear all data
viewModel.clear();

Lifecycle Callbacks

Intercept data loading lifecycle events with these callbacks on the View:

Callback	Triggered When
setOnLoad(OnLoad<Conversation>)	Data has been successfully loaded
setOnEmpty(OnEmpty)	The data list is empty after loading

Kotlin

conversations.setOnLoad { list ->
    // Called when conversations are loaded
    Log.d("Conversations", "Loaded ${list.size} conversations")
}

conversations.setOnEmpty {
    // Called when no conversations exist
    Log.d("Conversations", "No conversations found")
}

Java

conversations.setOnLoad(list -> {
    // Called when conversations are loaded
    Log.d("Conversations", "Loaded " + list.size() + " conversations");
});

conversations.setOnEmpty(() -> {
    // Called when no conversations exist
    Log.d("Conversations", "No conversations found");
});

Related

• Adapter Customization — Manipulate list data at the adapter level.
• Customization Overview — See all customization categories.