Watchlist events

∞ What is a Watchlist?

A Watchlist is a property associated with a user and provided during user authentication. A Watchlist is an array of user IDs which represent the circle of interest for the user (e.g., friends or followers). Users can be notified about the status (online/offline) of users they “watch”.

∞ Using Watchlist events

In order to use Watchlist events, here are the prerequisites:

1. Provide a Watchlist
2. Enable Watchlist events
3. Subscribe to Watchlist events

∞ Provide a Watchlist

Providing a watchlist for a user is optional. However, in order to receive Watchlist events, you need to provide the Watchlist during User Authentication.

∞ Enable Watchlist events

For Watchlist events to work, you must enable them for your application. To do that, go to the Channels dashboard, navigate to your app and App Settings, and turn on the Watchlist events toggle.

∞ Subscribe to Watchlist events

The client-side can subscribe to Watchlist events by using Client SDKs. The client-side needs to call pusher.signin() to start the user authentication process. Then, you can use pusher.user.watchlist.bind() to bind to Watchlist events. Example:

pusher.signin();

const watchlistEventHandler = (event) => {
    // event.user_ids
    // event.name
};
pusher.user.watchlist.bind('online', watchlistEventHandler);
pusher.user.watchlist.bind('offline', watchlistEventHandler);

pusher.User.Signin();

void watchlistEventHandler(WatchlistEvent watchlistEvent)
    {
        //watchlistEvent.UserIDs
        //watchlistEvent.Name
    }

pusher.User.Watchlist.Bind("online", watchlistEventHandler);
pusher.User.Watchlist.Bind("offline", watchlistEventHandler);

∞ Watchlist Online Status

The Online Status feature notifies a user about the status of the users in their watchlist. It indicates whether a user ID is online or offline for each user ID in the watchlist.

Once the user is authenticated, they will receive events indicating the current online status of peers in their watchlist. The user will continue to receive events for any further changes to the online status of users in the watchlist.

Receiving notifications about who in your circle is online or offline is useful in many scenarios.

Events associated with Online Status for Watchlists are:

• online
• offline

A user is considered online if that user is authenticated on at least one connection. A user can be authenticated on many connections and is still considered online. If a user is not authenticated on any connections, the user is considered offline.

Here’s a sequence diagram to showcase how the Watchlist Online Status works.