Lesson 7: Merge: Presence

merge: 'presence' tracks a list of connected users. It handles two events:

• 'join' - adds a user to the list (deduplicated by key)
• 'leave' - removes a user from the list by key

Unlike 'crud' which manages generic items, 'presence' is designed for tracking who's here right now.

Try it

The stream is set up with merge: 'presence'. Add two RPCs:

1. join(name) - creates a user object with a key field (use the name), adds it to the array if not already there, and publishes a 'join' event
2. leave(name) - removes the user from the array and publishes a 'leave' event with { key: name }

Then update the component: add a name input with a Join button, a Leave button when joined, and a list of online users. Try joining as different names in User A and User B!