Mention users

Tag users in chat messages with @ mentions. Type @ followed by at least three letters to see username suggestions.

You can use PubNub's functionality via Blueprints or directly in C++ code.

• In Blueprints, the whole SDK is managed by a subsystem, so start by initalizing the PubnubChatSubsystem node. Afterwards, you can use the Pubnub Chat object reference.

Blueprint functions

The Blueprints provided in the documentation show how you can structure your application and may contain utility methods and elements like buttons that are not part of the Unreal Chat SDK and are meant to serve as guidance.

• In C++, you can use the PubNub SDK as any other Game Instance Subsystem.

  #include "Kismet/GameplayStatics.h"
  #include "PubnubChatSubsystem.h"
  
  
  UGameInstance* GameInstance = UGameplayStatics::GetGameInstance(this);
  UPubnubChatSubsystem* PubnubChatSubsystem = GameInstance->GetSubsystem<UPubnubChatSubsystem>();
  
  
  UPubnubChat* Chat = PubnubChatSubsystem ->InitChat("demo", "demo", "my_user") // config optional

  Chat now allows you to call all Chat SDK functions, for example:

  Chat->DeleteUser("SomeUserID");

Usage in Blueprints and C++

Requires App Context

Enable App Context in the Admin Portal to mention users.

Shared structure

Channel references, user mentions, and links are MessageElement instances with different MentionTarget types.

Configuration options:

• User source: channel members or all app users
• Suggestions: up to 100 usernames (default: 10)
• Username length: up to 200 characters
• Mentions per message: up to 100 (default: 10)

Implementation follows similar patterns to channel referencing and links.

Add user mentions

AddMention() adds user mentions to a draft message. Use CreateUserMentionTarget() to create a mention target linking to a specified User.

Method signature

Add a user mention by calling AddMention() with the MentionTarget of type User.

Refer to the AddMention() method for details.

Sample code

Create the Hello Alex! I have sent you this link on the #offtopic channel. message where Alex is a user mention.

1// Create a message draft
2UPubnubMessageDraft* MyMessageDraft = Channel->CreateMessageDraft();
3

4// Insert the whole text to the message draft
5MyMessageDraft->InsertText(0, "Hello Alex! I have sent you this link on the #offtopic channel.");
6

7// Create a user mention target for Alex
8FString UserName = "Alex";
9UPubnubMentionTarget* UserMentionTarget = UPubnubMentionTarget::CreateUserMentionTarget(UserName);
10

11// Add the user mention for Alex
12MyMessageDraft->AddMention(6, UserName.Len(), UserMentionTarget); // 'Hello ' is 6 characters long
13

14// Send the message draft with the user mention
15MyMessageDraft->Send();

Remove user mentions

RemoveMention() removes a user mention from a draft message.

Method signature

Remove a user mention by calling RemoveMention() at the exact offset where the mention starts.

Refer to the RemoveMention() method for details.

Offset value

Provide the exact offset position where the mention starts; otherwise, it won't be removed.

Sample code

Remove the user mention from the Hello Alex! I have sent you this link on the #offtopic channel. message where Alex is a user mention.

1// Assume the message reads
2// Hello Alex! I have sent you this link on the #offtopic channel.`
3// Remove the user reference
4MessageDraft->RemoveMention(6)

Get user suggestions

AddChangeListenerWithSuggestions() returns users matching a 3-letter string from channel members or global users. Add a callback to listen for draft changes and receive suggestions for user mentions, links, and channel references.

AddChangeListenerWithSuggestions():

• Monitors updates to a message draft's content
• Provides the current state of message elements (TArray<UPubnubMessageElement*>)
• Offers FPubnubSuggestedMention items suggesting user mentions, links, or channel references

Unlike AddChangeListener(), which only tracks content changes, this method includes suggestion data for dynamic draft updates.

Single listener

Example: typing #Sup returns channels starting with Sup like Support or Support-Agents. Default: 10 suggestions (max: 100).

Method signature

Refer to the Add a message draft listener section for details.

Sample code

Insert the first mentioned user whenever the draft is updated and users are detected.

1// Assuming you have a UPubnubMessageDraft pointer named MyMessageDraft
2

3// Define your callback function to handle updates with suggestions
4void AMyActor::OnMessageDraftUpdateWithSuggestions(const TArray<UPubnubMessageElement*>& MessageElements, const TArray<FPubnubSuggestedMention>& SuggestedMentions)
5{
6    // Check if there are any suggested mentions
7    if (SuggestedMentions.Num() == 0)
8    {
9        return;
10    }
11

12    // Iterate over suggested mentions to find a user reference
13    for (const FPubnubSuggestedMention& Suggestion : SuggestedMentions)
14    {
15        // Check if the suggestion corresponds to a user reference
16        if (Suggestion.Target && Suggestion.Target->GetType() == EPubnubMentionTargetType::User) // Hypothetical check for user type
17        {
18            MyMessageDraft->InsertSuggestedMention(Suggestion, Suggestion.ReplaceTo);
19            break; // Stop after inserting the first user
20        }
21    }
22}
23

24// Set up the delegate to bind your callback
25FOnPubnubDraftUpdatedWithSuggestions DraftUpdateCallbackWithSuggestions;
26DraftUpdateCallbackWithSuggestions.BindDynamic(this, &AMyActor::OnMessageDraftUpdateWithSuggestions);
27

28// Add change listener with suggestions to the message draft
29MyMessageDraft->AddChangeListenerWithSuggestions(DraftUpdateCallbackWithSuggestions);
30

31// Example update to message draft
32MyMessageDraft->Update("Please check with Alex and provide your feedback.");

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Get mentioned users

MentionedUsers() returns all users mentioned in a message.

Method signature

Blueprint

C++ / Input parameters

1Message->MentionedUsers()

Output

Type	Description
TArray<FPubnubMentionedUser>	Array with specific mentioned users.

FPubnubMentionedUser

Property	Description
Id Type: FString	Unique identifier of the mentioned user.
Name Type: FString	Name of the mentioned user.

Sample code

Check if the last message on the support channel contains any mentions.

1#include "Kismet/GameplayStatics.h"
2#include "PubnubChatSubsystem.h"
3

4UGameInstance* GameInstance = UGameplayStatics::GetGameInstance(this);
5UPubnubChatSubsystem* PubnubChatSubsystem = GameInstance->GetSubsystem<UPubnubChatSubsystem>();
6

7UPubnubChat* Chat = PubnubChatSubsystem ->InitChat("demo", "demo", "my_user");
8

9UPubnubChannel* Channel = Chat->GetChannel("support");
10

11// Fetch historical messages
12TArray<UPubnubMessage*> Messages = Channel->GetHistory();
13

14UPubnubMessage* Message = Messages.Messages[0];
15

16TArray<FPubnubMentionedUser> MentionedUsers = Message->MentionedUsers();

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Collect all user-related mentions

GetCurrentUserMentions() retrieves all instances where the current user was mentioned in channels or threads. Use this to build a mentions feed.

Method signature

Blueprint

C++ / Input parameters

1Chat->GetCurrentUserMentions(FString StartTimetoken, FString EndTimetoken, int Count)

* required

Parameter	Description
StartTimetoken Type: FString Default: n/a	Timetoken delimiting the start of a time slice (exclusive) to pull messages with mentions from. For details, refer to the Fetch History section.
EndTimetoken Type: FString Default: n/a	Timetoken delimiting the end of a time slice (inclusive) to pull messages with mentions from. For details, refer to the Fetch History section.
Count Type: int Default: 100	Number of historical messages with mentions to return in a single call. Since each call returns all attached message reactions by default, the maximum number of returned messages is 100. For more details, refer to the description of the IncludeMessageActions parameter in the Unreal SDK docs.

Output

This method returns a FPubnubUserMentionDataList object containing two fields: UserMentions and IsMore.

Parameter	Description
UserMentions Type: TArray<FPubnubUserMentionData>	Array listing the requested number of historical mention events with a set of information that differ slightly depending on whether you were mentioned in the main (parent) channel or in a thread. For mentions in the parent channel, the returned information includes these fields: ChannelID where you were mentioned, UserID that mentioned you, Event (of type mention), and Message that included the mention. For mentions in threads, the returned information includes similar fields, the only difference is that you'll get ParentChannelID and ThreadChannelID fields instead of just ChannelId to clearly differentiate the thread that included the mention from the parent channel in which this thread was created.
isMore Type: bool	Info whether there are more historical events to pull.

Sample code

List the last ten mentions for the current chat user.

1#include "PubnubChatSubsystem.h"
2

3UGameInstance* GameInstance = UGameplayStatics::GetGameInstance(ContextObject);
4UPubnubChatSubsystem* PubnubChatSubsystem = GameInstance->GetSubsystem<UPubnubChatSubsystem>();
5

6UPubnubChat* Chat = PubnubChatSubsystem->InitChat("demo", "demo", "my_user");
7

8// Define the conversation/channel ID
9FString ChannelID = "ask-support"; 
10

11// Define the channel data
12FPubnubChatChannelData ChannelData;
13ChannelData.ChannelName = "ask-support";
14ChannelData.Description = "Space dedicated to answering all support-related questions";
15

16// Create the conversation
17UPubnubChannel* Channel = Chat->CreatePublicConversation(ChannelID, ChannelData);
18

19// Send text with mention
20FSendTextParams SendTextParams;
21SendTextParams.MentionedUsers.Add(1, "my_user");
22Channel->SendText(Message, SendTextParams);
23

24// Get mentions
25// start and end depends on needs
26UPubnubUserMentionDataList mentions = Channnel->GetCurrentUserMentions(10);
27for (FPubnubUserMentionData mention : mentions.UserMentions)
28{
29	UE_LOG(LogTemp, Info, TEXT(mention->ChannelID));
30	UE_LOG(LogTemp, Info, TEXT(mention->ChannelID));
31}

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Show notifications for mentions

ListenForEvents() monitors mention events in channels and threads you're a member of. Use this to trigger pop-up notifications.

Events documentation

See Chat events for details on mention event types.

Method signature

Blueprint

C++ / Input parameters

1Chat->ListenForEvents(
2    FString ChannelID, 
3    EPubnubChatEventType ChatEventType, 
4    FOnPubnubEventReceived EventCallback
5);

* required

Parameter	Description
ChannelID * Type: FString Default: user.id	Channel to listen for new mention events. In the case of mention events, this channel is always the current user's ID.
ChatEventType Type: EPubnubChatEventType Default: n/a	Type of events. PCET_MENTION is the type defined for all mention events
EventCallback * Type: FOnPubnubEventReceived Default: n/a	Callback function passed as a parameter. It defines the custom behavior to be executed whenever an mention event type is detected on the specified channel.

EPubnubChatEventType

Value	Description
PCET_TYPING	Indicates a user is typing a message. Displayed as Typing.
PCET_REPORT	Represents an event where a message has been flagged or reported for offensive content. Displayed as Report.
PCET_RECEIPT	Confirms receipt of a message or event. Displayed as Receipt.
PCET_MENTION	Indicates that a user has been mentioned in a message. Displayed as Mention.
PCET_INVITE	Represents an invitation event typically sent to a specific user. Displayed as Invite.
PCET_CUSTOM	Custom event type for specialized behavior or use cases. Displayed as Custom.
PCET_MODERATION	Represents an event related to content moderation actions. Displayed as Moderation.

Each function in the Unreal Chat SDK that takes a callback as a parameter requires you to handle the response type accordingly.

For example, you can bind a callback function for the Channel->StreamPresence method to its handler in the following way:

1// Create a pubnub response delegate
2// you MUST implement your own callback function to handle the response
3FOnPubnubChannelStreamPresenceReceived PresenceResponse;
4PresenceResponse.BindDynamic(this, &AMyActor::OnPresenceResponseReceived);
5

6Channel->StreamPresence(PresenceResponse);

You can implement the callback function to handle the response as follows:

AMyActor.h

1UFUNCTION()
2void OnPresenceResponseReceived(const TArray<FString> &PresentUsersIDs);

AMyActor.cpp

1void AMyActor::OnPresenceResponseReceived(const TArray<FString> &PresentUsersIDs)
2{
3	for(auto PresentUser : PresentUsersIDs)
4	{
5		UE_LOG(LogTemp, Log, TEXT("Present User ID: "), *PresentUser);
6	}
7}

Handle the response

Output

Type	Description
UPubnubCallbackStop*	Object on which you can call Stop() to stop receiving updates.

Sample code

Print a notification for a mention of the administrator chat user on the support channel.

1#include "Kismet/GameplayStatics.h"
2#include "PubnubChatSubsystem.h"
3

4UGameInstance* GameInstance = UGameplayStatics::GetGameInstance(this);
5UPubnubChatSubsystem* PubnubChatSubsystem = GameInstance->GetSubsystem<UPubnubChatSubsystem>();
6

7UPubnubChat* Chat = PubnubChatSubsystem ->InitChat("demo", "demo", "my_user");
8

9UPubnubChannel* Channel = Chat->GetChannel("support");
10

11FSendTextParams SendTextParams;
12FPubnubMentionedUser MentionedUser({"admin_george", "Administrator"});
13TMap<int, FPubnubMentionedUser> MentionedUsers;
14MentionedUsers.Add(1, MentionedUser);
15SendTextParams.MentionedUsers = MentionedUsers;
16

17// Create a pubnub response delegate
18// you MUST implement your own callback function to handle the response
19FOnPubnubEventReceived ListenResponse;
20ListenResponse.BindDynamic(this, &AMyActor::OnListenResponseReceived);
21

22Chat->ListenForEvents(
23    ChannelID,
24    EPubnubChatEventType::PCET_MENTION,
25    ListenResponse
26);
27

28Channel->SendText("@Administrator please intervene!", SendTextParams);

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