Manage channel updates

Update channel details and receive events whenever someone updates them.

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

To store data about channels, you must enable App Context for your app's keyset in the Admin Portal.

Update channel details

You can edit the metadata of an existing channel with Update() and UpdateChannel().

Both of them give the same output. The only difference is that you call a given method either on the Chat (UpdateChannel()) or the Channel (Update()) object. Depending on the object, these methods take a different set of input parameters - you either have to specify the channel ID you want to update or not because it's already known.

Method signature

Blueprint

C++ / Input parameters

• Channel->Update()

  1Channel->Update(FPubnubChatChannelData ChannelData);

• Chat->UpdateChannel()

  1Chat->UpdateChannel(
  2    FString ChannelID, 
  3    FPubnubChatChannelData ChannelData
  4);

Parameter	Required in Channel->Update()	Required in Chat->UpdateChannel()	Description
ChannelID Type: FString Default: n/a	No	Yes	Unique channel identifier.
ChannelData Type: FPubnubChatChannelData Default: n\a	No	No	Information about the channel.

FPubnubChatChannelData

* required

Parameter	Description
ChannelName Type: FString Default: n/a	Display name for the channel (must not be empty or consist only of whitespace characters).
Description Type: FString Default: n/a	Channel's identifier in an external system. You can use it to match id with a similar identifier from an external database.
CustomDataJson Type: FString Default: n/a	JSON providing custom data about the channel. Values must be scalar only; arrays or objects are not supported. Filtering App Context data through the custom property is not recommended in SDKs.
Status Type: FString Default: n/a	Tag that lets you categorize your app channels by their current state. The tag choice is entirely up to you and depends on your use case.
Type Type: FString Default: n/a	Tag that lets you categorize your app channels by their functional roles. The tag choice is entirely up to you and depends on your use case.

Output

Type	Description
UPubnubChannel*	Object returning the updated channel metadata.

Sample code

Update the description of the support channel.

• Update()

  1#include "Kismet/GameplayStatics.h"
  2#include "PubnubChatSubsystem.h"
  3
  
  4UGameInstance* GameInstance = UGameplayStatics::GetGameInstance(ContextObject);
  5UPubnubChatSubsystem* PubnubChatSubsystem = GameInstance->GetSubsystem<UPubnubChatSubsystem>();
  6
  
  7UPubnubChat* Chat = PubnubChatSubsystem->InitChat("demo", "demo", "my_user");
  8
  
  9UPubnubChannel* Channel = Chat->GetChannel("support");
  10
  
  11// Define the channel data
  12FPubnubChatChannelData ChannelData;
  13ChannelData.Description = "Channel for CRM tickets";
  14
  
  15Channel->Update(ChannelData);

• UpdateChannel()

  1#include "Kismet/GameplayStatics.h"
  2#include "PubnubChatSubsystem.h"
  3
  
  4UGameInstance* GameInstance = UGameplayStatics::GetGameInstance(ContextObject);
  5UPubnubChatSubsystem* PubnubChatSubsystem = GameInstance->GetSubsystem<UPubnubChatSubsystem>();
  6
  
  7UPubnubChat* Chat = PubnubChatSubsystem->InitChat("demo", "demo", "my_user");
  8
  
  9// Define the channel data
  10FPubnubChatChannelData ChannelData;
  11ChannelData.Description = "Channel for CRM tickets";
  12
  
  13Chat->UpdateChannel("support", ChannelData);

Get channel updates

You can receive updates when specific Channel object(s) are edited or removed on other clients using the following methods:

• StreamUpdates() checks updates on a single Channel object.
• StreamUpdatesOn() checks updates on a Channel object list.

Both methods accept a callback function as an argument. The Unreal Chat SDK invokes this callback whenever someone adds, changes, or removes channel metadata.

Underneath, these methods subscribe the current user to a channel and add an objects event listener to receive all objects events of type channel. These methods also return the unsubscribe function you can invoke to stop receiving objects events and unsubscribe from the channel.

Method signature

Blueprint

C++ / Input parameters

• StreamUpdates()

  1Channel->StreamUpdates(FOnPubnubChannelStreamUpdateReceived ChannelUpdateCallback);

• StreamUpdatesOn()

  1Channel->StreamUpdatesOn(
  2    TArray<UPubnubChannel*> Channels, 
  3    FOnPubnubChannelStreamUpdateReceived ChannelUpdateCallback
  4);

Parameter	Required in StreamUpdates()	Required in StreamUpdatesOn()	Description
Channels Type: TArray<UPubnubChannel*> Default: n/a	No	Yes	Array of Channel objects for which you want to get updates.
ChannelUpdateCallback Type: FOnPubnubChannelStreamUpdateReceived Default: n/a	Yes	Yes	Callback function passed as a parameter to both methods. It defines the custom behavior to be executed when detecting channel metadata changes.

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

• StreamUpdates()

  Get updates 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
  
  9// Get the channel and save the reference
  10UPubnubChannel* Channel = Chat->GetChannel("support");
  11
  
  12// Create a pubnub response delegate
  13// you MUST implement your own callback function to handle the response
  14FOnPubnubChannelStreamUpdateReceived StreamUpdatesResponse;
  15StreamUpdatesResponse.BindDynamic(this, &AMyActor::OnChannelUpdateResponseReceived);
  16
  
  17Channel->StreamUpdates(StreamUpdatesResponse);

  show all 17 lines

• StreamUpdatesOn()

  Get updates on the support and incident-management channels.

  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
  
  9// Get the channels and save the reference
  10UPubnubChannel* Channel1 = Chat->GetChannel("support");
  11UPubnubChannel* Channel2 = Chat->GetChannel("incident-management");
  12
  
  13TArray<UPubnubChannel*> Channels;
  14Channels.Add(Channel1);
  15Channels.Add(Channel2);
  16
  
  17// Create a pubnub response delegate
  18// you MUST implement your own callback function to handle the response
  19FOnPubnubChannelStreamUpdateReceived StreamUpdatesOnResponse;
  20StreamUpdatesOnResponse.BindDynamic(this, &AMyActor::OnChannelUpdateResponseReceived);
  21
  
  22Channel->StreamUpdatesOn(Channels, StreamUpdatesOnResponse);

  show all 22 lines

Other examples

• StreamUpdates()

  Stop listening to updates on the support channel.

  1auto StopUpdates = Channel->Channel->StreamUpdates(StreamUpdatesResponse);
  2
  
  3StopUpdates->Stop();

• StreamUpdatesOn()

  Stop listening to updates on the support and incident-management channels.

  1auto StopUpdates = Channel->StreamUpdatesOn(Channels, StreamUpdatesOnResponse);
  2
  
  3StopUpdates->Stop();