Reactions

Add, remove, and fetch emoji reactions on messages in your Flutter chat application using CometChat SDK.

AI Integration Quick Reference

Field	Value
Key Classes	BaseMessage, Reaction, ReactionCount, ReactionEvent, ReactionsRequest, ReactionsRequestBuilder
Key Methods	CometChat.addReaction(), CometChat.removeReaction(), ReactionsRequest.fetchNext(), ReactionsRequest.fetchPrevious(), CometChatHelper.updateMessageWithReactionInfo()
Listener Events	onMessageReactionAdded, onMessageReactionRemoved
Prerequisites	SDK initialized, user logged in

// Add a reaction to a message
CometChat.addReaction(messageId, "\U0001f600", onSuccess: (message) {
  debugPrint("Reaction added: ${message.getReactions().last}");
}, onError: (e) {});

// Remove a reaction from a message
CometChat.removeReaction(messageId, "\U0001f600", onSuccess: (message) {
  debugPrint("Reaction removed");
}, onError: (e) {});

// Fetch reactions for a message
ReactionsRequest request = (ReactionsRequestBuilder()
  ..messageId = messageId
  ..limit = 30
).build();
request.fetchNext(onSuccess: (reactions) {}, onError: (e) {});

// Listen for reaction events
CometChat.addMessageListener("LISTENER_ID", MessageListener(
  onMessageReactionAdded: (ReactionEvent event) {},
  onMessageReactionRemoved: (ReactionEvent event) {},
));

Reactions let users respond to messages with emoji. You can add or remove reactions, fetch all reactions on a message, listen for reaction events in real time, and update your UI when reactions change.

Reactions work on text messages, media messages, and custom messages.

Available via: SDK | REST API | UI Kits

Add a Reaction

Call addReaction() with a message ID and an emoji string.

Parameter	Type	Description
messageId	int	The ID of the message to react to.
reaction	String	The reaction emoji (e.g., "\U0001f600", "\U0001f44d").

Dart

int messageId = 1;

CometChat.addReaction(messageId, "\U0001f634", onSuccess: (message) {
  debugPrint("Success : ${message.getReactions().last}");
}, onError: (e) {
  debugPrint("Error: ${e.message}");
});   

Response

On Success — A BaseMessage object representing the message with the reaction added:

BaseMessage Object:

Parameter	Type	Description	Sample Value
id	number	Unique message ID	401
metadata	object	Custom metadata attached to the message	{}
receiver	object	Receiver user object	See below \u2193
editedBy	string	UID of the user who edited the message	null
conversationId	string	Unique conversation identifier	"cometchat-uid-1_user_cometchat-uid-2"
sentAt	number	Epoch timestamp when the message was sent	1745554729
receiverUid	string	UID of the receiver	"cometchat-uid-2"
type	string	Type of the message	"text"
readAt	number	Epoch timestamp when the message was read	0
deletedBy	string	UID of the user who deleted the message	null
deliveredAt	number	Epoch timestamp when the message was delivered	1745554750
deletedAt	number	Epoch timestamp when the message was deleted	0
replyCount	number	Number of replies to this message	0
sender	object	Sender user object	See below \u2193
receiverType	string	Type of the receiver	"user"
editedAt	number	Epoch timestamp when the message was edited	0
parentMessageId	number	ID of the parent message (for threads)	0
readByMeAt	number	Epoch timestamp when read by the current user	0
category	string	Message category	"message"
deliveredToMeAt	number	Epoch timestamp when delivered to the current user	0
updatedAt	number	Epoch timestamp when the message was last updated	1745554729
unreadRepliesCount	number	Count of unread replies	0
quotedMessageId	number	ID of the quoted message	null

---

sender Object:

Parameter	Type	Description	Sample Value
uid	string	Unique identifier of the sender	"cometchat-uid-1"
name	string	Display name of the sender	"Andrew Joseph"
link	string	Profile link	null
avatar	string	Avatar URL	"https://assets.cometchat.io/sampleapp/v2/users/cometchat-uid-1.webp"
metadata	object	Custom metadata	{}
status	string	Online status	"online"
role	string	User role	"default"
statusMessage	string	Status message	null
tags	array	User tags	[]
hasBlockedMe	boolean	Whether this user has blocked the current user	false
blockedByMe	boolean	Whether the current user has blocked this user	false
lastActiveAt	number	Epoch timestamp of last activity	1745554700

---

receiver Object:

Parameter	Type	Description	Sample Value
uid	string	Unique identifier of the receiver	"cometchat-uid-2"
name	string	Display name of the receiver	"George Alan"
link	string	Profile link	null
avatar	string	Avatar URL	"https://assets.cometchat.io/sampleapp/v2/users/cometchat-uid-2.webp"
metadata	object	Custom metadata	{}
status	string	Online status	"offline"
role	string	User role	"default"
statusMessage	string	Status message	null
tags	array	User tags	[]
hasBlockedMe	boolean	Whether this user has blocked the current user	false
blockedByMe	boolean	Whether the current user has blocked this user	false
lastActiveAt	number	Epoch timestamp of last activity	1745550000

Error

Parameter	Type	Description	Sample Value
code	string	Error code identifier	"ERR_CHAT_API_FAILURE"
message	string	Human-readable error message	"Failed to process the reaction."
details	string	Additional technical details	"An unexpected error occurred while processing the request."

Remove a Reaction

Call removeReaction() with the same message ID and emoji.

Parameter	Type	Description
messageId	int	The ID of the message to remove the reaction from.
reaction	String	The reaction emoji to remove (e.g., "\U0001f600", "\U0001f44d").

Dart

int messageId = 1;

CometChat.removeReaction(messageId, "\U0001f634", onSuccess: (message) {
  debugPrint("Success : ${message.getReactions().last}");
}, onError: (e) {
  debugPrint("Error: ${e.message}");
});

Response

On Success — A BaseMessage object representing the message with the reaction removed:

BaseMessage Object:

Parameter	Type	Description	Sample Value
id	number	Unique message ID	401
metadata	object	Custom metadata attached to the message	{}
receiver	object	Receiver user object	See below \u2193
editedBy	string	UID of the user who edited the message	null
conversationId	string	Unique conversation identifier	"cometchat-uid-1_user_cometchat-uid-2"
sentAt	number	Epoch timestamp when the message was sent	1745554729
receiverUid	string	UID of the receiver	"cometchat-uid-2"
type	string	Type of the message	"text"
readAt	number	Epoch timestamp when the message was read	0
deletedBy	string	UID of the user who deleted the message	null
deliveredAt	number	Epoch timestamp when the message was delivered	1745554750
deletedAt	number	Epoch timestamp when the message was deleted	0
replyCount	number	Number of replies to this message	0
sender	object	Sender user object	See below \u2193
receiverType	string	Type of the receiver	"user"
editedAt	number	Epoch timestamp when the message was edited	0
parentMessageId	number	ID of the parent message (for threads)	0
readByMeAt	number	Epoch timestamp when read by the current user	0
category	string	Message category	"message"
deliveredToMeAt	number	Epoch timestamp when delivered to the current user	0
updatedAt	number	Epoch timestamp when the message was last updated	1745554729
unreadRepliesCount	number	Count of unread replies	0
quotedMessageId	number	ID of the quoted message	null

---

sender Object:

Parameter	Type	Description	Sample Value
uid	string	Unique identifier of the sender	"cometchat-uid-1"
name	string	Display name of the sender	"Andrew Joseph"
link	string	Profile link	null
avatar	string	Avatar URL	"https://assets.cometchat.io/sampleapp/v2/users/cometchat-uid-1.webp"
metadata	object	Custom metadata	{}
status	string	Online status	"online"
role	string	User role	"default"
statusMessage	string	Status message	null
tags	array	User tags	[]
hasBlockedMe	boolean	Whether this user has blocked the current user	false
blockedByMe	boolean	Whether the current user has blocked this user	false
lastActiveAt	number	Epoch timestamp of last activity	1745554700

---

receiver Object:

Parameter	Type	Description	Sample Value
uid	string	Unique identifier of the receiver	"cometchat-uid-2"
name	string	Display name of the receiver	"George Alan"
link	string	Profile link	null
avatar	string	Avatar URL	"https://assets.cometchat.io/sampleapp/v2/users/cometchat-uid-2.webp"
metadata	object	Custom metadata	{}
status	string	Online status	"offline"
role	string	User role	"default"
statusMessage	string	Status message	null
tags	array	User tags	[]
hasBlockedMe	boolean	Whether this user has blocked the current user	false
blockedByMe	boolean	Whether the current user has blocked this user	false
lastActiveAt	number	Epoch timestamp of last activity	1745550000

Error

Parameter	Type	Description	Sample Value
code	string	Error code identifier	"ERR_CHAT_API_FAILURE"
message	string	Human-readable error message	"Failed to process the reaction."
details	string	Additional technical details	"An unexpected error occurred while processing the request."

Both addReaction() and removeReaction() return a BaseMessage object with the updated reactions.

Read Reaction Data from a Message

Any BaseMessage exposes reaction data through its reactions property:

Get All Reactions

Use the reactions property to retrieve the list of reactions on a message. Returns a List<ReactionCount> containing the reactions, or an empty list if no one has reacted.

Dart

message.reactions

Check if the Logged-in User Has Reacted

Use the reactedByMe property on any ReactionCount object to check whether the logged-in user has reacted with that particular emoji. Returns true if they have, false otherwise.

Dart

for (ReactionCount reactionCount in message.reactions) {
    debugPrint("isReactedByMe ${reactionCount.reactedByMe}"); //Return true is logged-in user reacted on that message, otherwise false
}

Fetch Reactions for a Message

To get the full list of who reacted with what on a specific message, use ReactionsRequestBuilder. You can paginate through results with fetchNext() and fetchPrevious() (max 100 per request).

Builder Property	Type	Description
messageId	int?	The message ID to fetch reactions for. Required.
reaction	String?	Filter to a specific emoji (e.g., "\U0001f60a"). When set, only reactions matching this emoji are returned.
limit	int	Number of reactions to fetch per request. Default is 10.

Fetch Next

The fetchNext() method fetches the next set of reactions for the message.

Dart

int messageId = 1;

ReactionsRequest reactionsRequest = (ReactionsRequestBuilder()
  ..limit = 30
  ..messageId = messageId
).build();

reactionsRequest.fetchNext(
  onSuccess: (reactions) {
    for (Reaction reaction in reactions) {
      debugPrint("Success: $reaction");
    }
  },
  onError: (e) {
    debugPrint("Error: ${e.message}");
  },
);

The fetchNext() method returns a List<Reaction> representing individual user reactions on the message.

Response

On Success — A list of Reaction objects for the message:

Reaction Object (per item in list):

Parameter	Type	Description	Sample Value
id	string	Unique reaction identifier	"r1"
messageId	number	ID of the message this reaction belongs to	1
reaction	string	The reaction emoji	"\U0001f634"
uid	string	UID of the user who reacted	"cometchat-uid-1"
reactedAt	number	Epoch timestamp when the reaction was added	1745554729
reactedBy	object	User who added the reaction	See below \u2193

---

reactedBy Object:

Parameter	Type	Description	Sample Value
uid	string	Unique identifier of the user	"cometchat-uid-1"
name	string	Display name of the user	"Andrew Joseph"
link	string	Profile link	null
avatar	string	Avatar URL	"https://assets.cometchat.io/sampleapp/v2/users/cometchat-uid-1.webp"
metadata	object	Custom metadata	{}
status	string	Online status	"online"
role	string	User role	"default"
statusMessage	string	Status message	null
tags	array	User tags	[]
hasBlockedMe	boolean	Whether this user has blocked the current user	false
blockedByMe	boolean	Whether the current user has blocked this user	false
lastActiveAt	number	Epoch timestamp of last activity	1745554700

Error

Parameter	Type	Description	Sample Value
code	string	Error code identifier	"ERR_CHAT_API_FAILURE"
message	string	Human-readable error message	"Failed to fetch the requested data."
details	string	Additional technical details	"An unexpected error occurred while processing the request."

Fetch Previous

The fetchPrevious() method fetches the previous set of reactions for the message.

Dart

int messageId = 1;

ReactionsRequest reactionsRequest = (ReactionsRequestBuilder()
  ..limit = 30
  ..messageId = messageId
).build();

reactionsRequest.fetchPrevious(
  onSuccess: (reactions) {
    for (Reaction reaction in reactions) {
      debugPrint("Success: $reaction");
    }
  },
  onError: (e) {
    debugPrint("Error: ${e.message}");
  },
);

Response

On Success — A list of Reaction objects for the message:

Reaction Object (per item in list):

Parameter	Type	Description	Sample Value
id	string	Unique reaction identifier	"r1"
messageId	number	ID of the message this reaction belongs to	1
reaction	string	The reaction emoji	"\U0001f634"
uid	string	UID of the user who reacted	"cometchat-uid-1"
reactedAt	number	Epoch timestamp when the reaction was added	1745554729
reactedBy	object	User who added the reaction	See below \u2193

---

reactedBy Object:

Parameter	Type	Description	Sample Value
uid	string	Unique identifier of the user	"cometchat-uid-1"
name	string	Display name of the user	"Andrew Joseph"
link	string	Profile link	null
avatar	string	Avatar URL	"https://assets.cometchat.io/sampleapp/v2/users/cometchat-uid-1.webp"
metadata	object	Custom metadata	{}
status	string	Online status	"online"
role	string	User role	"default"
statusMessage	string	Status message	null
tags	array	User tags	[]
hasBlockedMe	boolean	Whether this user has blocked the current user	false
blockedByMe	boolean	Whether the current user has blocked this user	false
lastActiveAt	number	Epoch timestamp of last activity	1745554700

Error

Parameter	Type	Description	Sample Value
code	string	Error code identifier	"ERR_CHAT_API_FAILURE"
message	string	Human-readable error message	"Failed to fetch the requested data."
details	string	Additional technical details	"An unexpected error occurred while processing the request."

Real-Time Reaction Events

Register a MessageListener to receive reaction events as they happen. This is how you keep your UI in sync when other users add or remove reactions.

Dart

class MyClass with MessageListener {

  String listenerID = "UNIQUE_LISTENER_ID";

  MyClass() {
    CometChat.addMessageListener(listenerID, this);
  }

  @override
  void onMessageReactionAdded(ReactionEvent reactionEvent) {
    debugPrint("Reaction added ${reactionEvent.reaction}");
  }

  @override
  void onMessageReactionRemoved(ReactionEvent reactionEvent) {
    debugPrint("Reaction removed ${reactionEvent.reaction}");
  }
}

Each reaction listener callback receives a ReactionEvent object containing:

Parameter	Type	Description
reaction	Reaction?	The reaction that was added or removed.
receiverId	String?	The UID or GUID of the receiver.
receiverType	String?	The type of the receiver ("user" or "group").
conversationId	String?	The unique conversation identifier.
parentMessageId	int?	The ID of the parent message (for threaded messages).

Remove the Listener

Dart

String listenerID = "UNIQUE_LISTENER_ID";

CometChat.removeMessageListener(listenerID);

Always remove listeners when they’re no longer needed (e.g., in the dispose() method). Failing to remove listeners can cause memory leaks and duplicate event handling.

Update a Message with Reaction Info

When you receive a real-time reaction event, you’ll want to update the corresponding message object so your UI reflects the change. CometChatHelper.updateMessageWithReactionInfo() does this — it takes the BaseMessage instance, the Reaction event data, and the action type, then returns the updated message.

Parameter	Type	Description
baseMessage	BaseMessage	The message object to update.
messageReaction	Reaction	The reaction event received from the listener.
action	String	ReactionAction.reactionAdded or ReactionAction.reactionRemoved

Dart

// Pass the message and Reaction from your listener (e.g. onMessageReactionAdded)
Future<void> refreshMessageWithReaction(
  BaseMessage message,
  Reaction messageReaction,
) async {
  // The received reaction event action type: reactionAdded or reactionRemoved
  var action = ReactionAction.reactionAdded;

  BaseMessage? modifiedBaseMessage =
      await CometChatHelper.updateMessageWithReactionInfo(
    message,
    messageReaction,
    action,
  );
  // Use modifiedBaseMessage?.reactions to refresh your UI
}

After calling this method, use modifiedBaseMessage?.reactions to get the latest reactions and refresh your UI.

---

Next Steps

Send Messages

Send text, media, and custom messages to users and groups

Receive Messages

Listen for incoming messages in real-time and fetch missed messages

Threaded Messages

Create and manage message threads

Mentions

Mention users and groups in messages