Reference channels

Channel referencing lets users mention channels in messages by typing # followed by at least three letters. Matching channel names appear as 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 for your keyset in the Admin Portal.

Generic referencing

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

Suggestions include all channels in the app keyset (up to 100), regardless of user membership. Configure up to 100 channel references per message (default: 10) and display them as links.

Implementation is similar to user mentions and links.

Add channel references

Add channel references with # followed by at least three letters of the channel name (e.g., #Sup). Use CreateChannelMentionTarget() to create a mention target linking to a specified Channel.

Method signature

Add a channel reference by calling AddMention() with the MentionTarget of type Channel.

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 #offtopic is a channel reference (channel name is offtopic).

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 channel mention target for #offtopic
8FString ChannelName = "offtopic";
9UPubnubMentionTarget* ChannelMentionTarget = UPubnubMentionTarget::CreateChannelMentionTarget(ChannelName);
10

11// Add the channel mention for #offtopic - '#offtopic' is mention of 'offtopic' channel
12MyMessageDraft->AddMention(45, ChannelName.Len() +1, ChannelMentionTarget); 
13// 45 is Possition of # in the text.
14// ChannelName.Len() +1 because we add # to the reference
15

16// Send the message draft with the channel mention
17MyMessageDraft->Send();

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Remove channel references

Remove a channel reference from a draft message with RemoveMention().

Method signature

Remove channel references by calling RemoveMention() at the exact offset where the reference starts.

Refer to the RemoveMention() method for details.

Offset value

Provide the exact position of the first character; otherwise the element is not removed.

Sample code

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

1// Assume the message reads
2// Hello Alex! I have sent you this link on the #offtopic channel.`
3// Remove the channel reference for "#offtopic"
4MessageDraft->RemoveMention(45)

Get channel suggestions

The message elements listener returns matching channels from your keyset for the 3-letter string typed after #.

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

Typing #Sup returns channels 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 referenced channel whenever the draft is updated and channels 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 channel reference
13    for (const FPubnubSuggestedMention& Suggestion : SuggestedMentions)
14    {
15        // Check if the suggestion corresponds to a channel reference
16        if (Suggestion.Target && Suggestion.Target->GetType() == EPubnubMentionTargetType::Channel) // Hypothetical check for channel type
17        {
18            MyMessageDraft->InsertSuggestedMention(Suggestion, Suggestion.ReplaceTo);
19            break; // Stop after inserting the first channel
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(TEXT("Alex, please review the changes in the #general channel."));

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Get referenced channels

ReferencedChannels() returns all channel names referenced in a message.

Method signature

Blueprint

C++ / Input parameters

1Message->ReferencedChannels();

Output

Type	Description
TArray<FPubnubReferencedChannel>	Returned array of referenced channel (FString ID, FString Name) objects.

Sample code

Check if a message on the support channel contains any channel references.

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

11FString Timetoken = "17228457425416757";
12

13// Fetch the message
14UPubnubMessage* Message = Channel->GetMessage(Timetoken);
15

16TArray<FPubnubReferencedChannel> ReferencedChannels = Message->ReferencedChannels();

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