Channel groups

Channel groups let you manage and subscribe to multiple channels as a single unit. Instead of subscribing to each channel individually, you can add channels to a group and receive messages from all of them with a single subscription.

This is useful when you need to:

• Subscribe to all channels a user is a member of with one call.
• Monitor presence across multiple channels simultaneously.
• Dynamically manage channel subscriptions without reconnecting.

You can't publish to a channel group. You can only subscribe to it. To publish within a channel group, you need to publish to each channel individually.

Requires Stream Controller add-on

This method requires that the Stream Controller add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

Get channel group reference

Use the getChannelGroup() method on the Chat object to get a reference to a channel group. This method doesn't create the group on the server, but returns a handle you can use to manage the group.

If the group exists, the reference points to it. If the group doesn't exist, it serves as a handle to create and modify it by adding channels to it.

Method signature

This method takes the following parameters:

1chat.getChannelGroup(id: String): ChannelGroup

Input

* required

Parameter	Description
id * Type: String Default: n/a	Unique identifier for the channel group.

Output

Type	Description
ChannelGroup	A ChannelGroup object you can use to manage the group.

Sample code

Get a reference to a channel group named my-channel-group.

1val channelGroup = chat.getChannelGroup("my-channel-group")

Remove channel group

Use the removeChannelGroup() method to delete a channel group from the server.

Method signature

This method takes the following parameters:

1chat.removeChannelGroup(id: String): PNFuture<Unit>

Input

* required

Parameter	Description
id * Type: String Default: n/a	Unique identifier of the channel group to remove.

Output

Type	Description
PNFuture<Unit>	Returns an empty response when the channel group is successfully removed.

Sample code

Remove a channel group named my-channel-group.

1chat.removeChannelGroup("my-channel-group").async { result ->
2    result.onSuccess {
3        // Channel group removed successfully
4    }.onFailure {
5        // Handle failure
6    }
7}

List channels

Use the listChannels() method to get a paginated list of all channels in a channel group.

Method signature

This method takes the following parameters:

1channelGroup.listChannels(
2    filter: String? = null,
3    sort: Collection<PNSortKey<PNKey>> = listOf(),
4    limit: Int? = null,
5    page: PNPage? = null
6): PNFuture<GetChannelsResponse>

Input

* required

Parameter	Description
filter Type: String Default: n/a	Expression used to filter the results. Returns only the channels whose properties satisfy the given expression. The filter language is defined here.
sort Type: Collection<PNSortKey<PNKey>> Default: listOf()	A collection to specify the sort order. Available options are id, name, and updated. Use asc or desc to specify the sorting direction. For example: listOf(PNSortKey.asc(PNKey.NAME)).
limit Type: Int Default: 100	Number of objects to return in response. The default (and maximum) value is 100.
page Type: PNPage Default: n/a	Object used for pagination to define which previous or next result page you want to fetch.

Output

Type	Description
PNFuture<GetChannelsResponse>	PNFuture containing a set of channels with pagination information (next, prev, total).

Sample code

List all channels in a channel group.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3channelGroup.listChannels().async { result ->
4    result.onSuccess { response ->
5        response.channels.forEach { channel ->
6            println("Channel: ${channel.id}")
7        }
8    }.onFailure {
9        // Handle failure
10    }
11}

Add channels

Use the addChannels() method to add Channel entities to a channel group.

Method signature

This method takes the following parameters:

1channelGroup.addChannels(channels: Collection<Channel>): PNFuture<Unit>

Input

* required

Parameter	Description
channels * Type: Collection<Channel> Default: n/a	Collection of Channel entities to add to the group.

Output

Type	Description
PNFuture<Unit>	Returns an empty response when channels are successfully added.

Sample code

Add two channels to a channel group.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3chat.getChannel("support-channel").async { result ->
4    result.onSuccess { supportChannel ->
5        chat.getChannel("general-channel").async { result2 ->
6            result2.onSuccess { generalChannel ->
7                if (supportChannel != null && generalChannel != null) {
8                    channelGroup.addChannels(listOf(supportChannel, generalChannel))
9                        .async { addResult ->
10                            addResult.onSuccess {
11                                // Channels added successfully
12                            }.onFailure {
13                                // Handle failure
14                            }
15                        }
16                }
17            }
18        }
19    }
20}

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Add channel identifiers

Use the addChannelIdentifiers() method to add channels to a group using only their IDs. This method reduces the overhead of fetching full Channel entities when you only know the IDs.

No validation

This method doesn't validate whether channels with the given IDs exist. Make sure the channel IDs are valid before adding them.

Method signature

This method takes the following parameters:

1channelGroup.addChannelIdentifiers(ids: Collection<String>): PNFuture<Unit>

Input

* required

Parameter	Description
ids * Type: Collection<String> Default: n/a	Collection of channel IDs to add to the group.

Output

Type	Description
PNFuture<Unit>	Returns an empty response when channel identifiers are successfully added.

Sample code

Add channels by their IDs.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3channelGroup.addChannelIdentifiers(listOf("support-channel", "general-channel")).async { result ->
4    result.onSuccess {
5        // Channel identifiers added successfully
6    }.onFailure {
7        // Handle failure
8    }
9}

Remove channels

Use the removeChannels() method to remove Channel entities from a channel group.

Method signature

This method takes the following parameters:

1channelGroup.removeChannels(channels: Collection<Channel>): PNFuture<Unit>

Input

* required

Parameter	Description
channels * Type: Collection<Channel> Default: n/a	Collection of Channel entities to remove from the group.

Output

Type	Description
PNFuture<Unit>	Returns an empty response when channels are successfully removed.

Sample code

Remove channels from a channel group.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3// Assuming you have Channel references
4channelGroup.removeChannels(listOf(supportChannel, generalChannel)).async { result ->
5    result.onSuccess {
6        // Channels removed successfully
7    }.onFailure {
8        // Handle failure
9    }
10}

Remove channel identifiers

Use the removeChannelIdentifiers() method to remove channels from a group using only their IDs.

No validation

This method doesn't validate whether channels with the given IDs exist in the group. Make sure the channel IDs are valid before removing them.

Method signature

This method takes the following parameters:

1channelGroup.removeChannelIdentifiers(ids: Collection<String>): PNFuture<Unit>

Input

* required

Parameter	Description
ids * Type: Collection<String> Default: n/a	Collection of channel IDs to remove from the group.

Output

Type	Description
PNFuture<Unit>	Returns an empty response when channel identifiers are successfully removed.

Sample code

Remove channels by their IDs.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3channelGroup.removeChannelIdentifiers(listOf("support-channel", "general-channel")).async { result ->
4    result.onSuccess {
5        // Channel identifiers removed successfully
6    }.onFailure {
7        // Handle failure
8    }
9}

Watch channel group

Use the connect() method to start receiving messages from all channels in the group. This subscribes to all channels in the group and invokes your callback whenever a message is received on any channel in the group.

Method signature

This method takes the following parameters:

1channelGroup.connect(callback: (Message) -> Unit): AutoCloseable

Input

* required

Parameter	Description
callback * Type: (Message) -> Unit Default: n/a	Callback function invoked whenever a message is received on any channel in the group.

Output

Type	Description
AutoCloseable	Interface you can call to stop listening for new messages by invoking the close() method.

Sample code

Start receiving messages from all channels in a group.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3val subscription = channelGroup.connect { message ->
4    println("Received message on channel ${message.channelId}: ${message.text}")
5}
6

7// Later, when you want to stop receiving messages
8subscription.close()

Get present users

Use the whoIsPresent() method to get a list of users currently present on any channel within the channel group.

Requires Presence

This method requires that Presence is enabled for your app's keyset in the Admin Portal.

Method signature

This method has the following signature:

1channelGroup.whoIsPresent(): PNFuture<Map<String, Collection<String>>>

Input

This method doesn't take any parameters.

Output

Type	Description
PNFuture<Map<String, Collection<String>>>	A map where each key is a channel ID and the value is a collection of user IDs present on that channel.

Sample code

Get all users present on channels in a group.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3channelGroup.whoIsPresent().async { result ->
4    result.onSuccess { presenceByChannel ->
5        presenceByChannel.forEach { (channelId, userIds) ->
6            println("Channel $channelId has users: $userIds")
7        }
8    }.onFailure {
9        // Handle failure
10    }
11}

Stream presence

Use the streamPresence() method to receive real-time updates when users join or leave any channel in the group.

Requires Presence

This method requires that Presence is enabled for your app's keyset in the Admin Portal.

Method signature

This method takes the following parameters:

1channelGroup.streamPresence(
2    callback: (presenceByChannels: Map<String, Collection<String>>) -> Unit
3): AutoCloseable

Input

* required

Parameter	Description
callback * Type: (Map<String, Collection<String>>) -> Unit Default: n/a	Callback function invoked when presence changes. Receives a map where each key is a channel ID and the value is a collection of user IDs present on that channel.

Output

Type	Description
AutoCloseable	Interface you can call to stop receiving presence updates by invoking the close() method.

Sample code

Stream presence updates for all channels in a group.

1val channelGroup = chat.getChannelGroup("my-channel-group")
2

3val presenceSubscription = channelGroup.streamPresence { presenceByChannel ->
4    presenceByChannel.forEach { (channelId, userIds) ->
5        println("Channel $channelId now has users: $userIds")
6    }
7}
8

9// Later, when you want to stop receiving presence updates
10presenceSubscription.close()