Manage channel updates

Update channel details and receive events whenever someone updates them.

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

update() and updateChannel() call PubNub App Context API and the JavaScript SDK setChannelMetadata() method.

Under the hood

These methods take the following parameters:

• update()

  1channel.update(
  2    {
  3        name?: string,
  4        custom?: ObjectCustom,
  5        description?: string,
  6        status?: string,
  7        type?: string
  8    }
  9): Promise<Channel>

• updateChannel()

  1chat.updateChannel(
  2    id: string,
  3    {
  4        name?: string,
  5        custom?: ObjectCustom,
  6        description?: string,
  7        status?: string,
  8        type?: string
  9    }
  10): Promise<Channel>

Input

Parameter	Required in update()	Required in updateChannel()	Description
id Type: string Default: n/a	No	Yes	Unique channel identifier.
name Type: string Default: n/a	No	No	Display name for the channel.
custom Type: ObjectCustom Default: n/a	No	No	JSON providing custom data about the channel. Values must be scalar only; arrays or objects are not supported. App Context filtering language doesn’t support filtering by custom properties.
description Type: string Default: n/a	No	No	Additional details about the channel.
status Type: string Default: n/a	No	No	Tag that categorizes a channel by its state, like archived.
type Type: string Default: n/a	No	No	Tag that categorizes a channel by its function, like offtopic.

API limits

To learn about the maximum length of parameters used to set channel metadata, refer to REST API docs.

Output

Type	Description
Promise<Channel>	Object returning the updated channel metadata.

Errors

Whenever the channel ID is required, and you try to edit a channel without providing its ID, you will receive the ID is required error. If the channel you're trying to edit doesn't exist, you'll receive the Channel with this ID does not exist error.

Sample code

Update the description of the support channel.

• update()

  1// reference the "channel" object
  2const channel = await chat.getChannel("support")
  3// invoke the "update()" method on the "channel" object
  4await channel.update(
  5    {
  6        description: "Channel for CRM tickets"
  7    }
  8)

• updateChannel()

  1// reference the "chat" object and invoke the "updateChannel()" method
  2const channel = await chat.updateChannel(
  3    "support",
  4    {
  5        description: "Channel for CRM tickets"
  6    }
  7)

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 Chat SDK invokes this callback whenever someone 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.

Stream update behavior

• streamUpdates() returns the entire updated Channel object each time a change occurs. If the callback receives null, the channel has been deleted.
• streamUpdatesOn() returns the complete list of channels you're monitoring each time any change occurs to any of them.

Method signature

streamUpdates() and streamUpdatesOn() call Pub/Sub API and the JavaScript SDK subscribe() and unsubscribe() methods.

Under the hood

These methods take the following parameters:

• streamUpdates()

  1channel.streamUpdates(
  2    callback: (channel: Channel) => unknown
  3): () => void

• streamUpdatesOn()

  1static Channel.streamUpdatesOn(
  2    channels: Channel[],
  3    callback: (channels: Channel[]) => unknown
  4): () => void

Input

Parameter	Required in streamUpdates()	Required in streamUpdatesOn()	Description
channels Type: Channel[] Default: n/a	No	Yes	Array of Channel objects for which you want to get updates.
callback Type: n/a 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.
→ channel Type: Channel Default: n/a	Yes	No	Returned Channel object with the updated data.
→ channels Type: Channel[] Default: n/a	No	Yes	Returned array of Channel objects with the updated data.

Output

Type	Description
() => void	Function you can call to disconnect (unsubscribe) from the channel and stop receiving objects events.

Errors

Whenever a list of Channel objects is required as a parameter, and you try to get updates on channels without specifying their list, you will receive the Cannot stream channel updates on an empty list error.

Sample code

• streamUpdates()

  Get updates on the support channel.

  1const channel = await chat.getChannel("support")
  2channel.streamUpdates((channel) => {
  3    // The callback receives the entire updated Channel object each time a change occurs.
  4    if (channel) {
  5        console.log("Updated channel: ", channel)
  6    } else {
  7        console.log("Channel was deleted")
  8    }
  9})

• streamUpdatesOn()

  Get updates on the support and incident-management channels.

  1const supportChannel = await chat.getChannel("support")
  2const incidentChannel = await chat.getChannel("incident-management")
  3Channel.streamUpdatesOn([supportChannel, incidentChannel], (channels) => {
  4    // The callback receives the complete list of all channels you're monitoring
  5    // each time any change occurs.
  6    console.log("Updated channels: ", channels)
  7})

Other examples

• streamUpdates()

  Stop listening to updates on the support channel.

  1const channel = await chat.getChannel("support")
  2const stopUpdates = channel.streamUpdates(/* handle update callback */)
  3// after some time...
  4stopUpdates()

• streamUpdatesOn()

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

  1const supportChannel = await chat.getChannel("support")
  2const incidentChannel = await chat.getChannel("incident-management")
  3const stopUpdates = Channel.streamUpdatesOn([supportChannel, incidentChannel], /* handle update callback */)
  4// after some time...
  5stopUpdates()