Android Example [B4X] Supabase - Realtime Presence

[B4X] Supabase - The Open Source Firebase alternative

Supabase is an open source Firebase alternative. It provides all the backend services you need to build a product. Supabase uses Postgres database with real-time capabilities. Basically, supabase provides an interface to manage postgres database that you can use to create table and insert, edit...

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Share state between users with Realtime Presence.

Presence | Supabase Docs

Share state between users with Realtime Presence.

supabase.com

Setup

[B4X] Supabase - Realtime

https://www.b4x.com/android/forum/threads/b4x-supabase-the-open-source-firebase-alternative.149855/ This is a very simple tutorial on how to use the Realtime module. A more detailed tutorial is coming soon. Step 1 Click in your project on "Project -> Build configurations -> Conditional...

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Sync and track state
Listen to the sync, join, and leave events triggered whenever any client joins or leaves the channel or changes their slice of state:

    Realtime _
    .Channel("Room1","","") _
    .On(Realtime.SubscribeType_Presence) _
    .Event(Realtime.Event_Sync) _
    .On(Realtime.SubscribeType_Presence) _
    .Event(Realtime.Event_Join) _
    .On(Realtime.SubscribeType_Presence) _
    .Event(Realtime.Event_Leave) _
    .Subscribe

Sending state
You can send state to all subscribers using track:

Channel1.Track(CreateMap("user":"user-1","online_at":DateUtils.TicksToString(DateTime.Now)))

Stop tracking
You can stop tracking presence using the untrack() method. This will trigger the sync and leave event handlers.

Channel1.Untrack

Events

Private Sub Realtime_PresenceDataReceived(PresenceData As SupabaseRealtime_PresenceData)
    
    Log("Presence data:")
    
    Dim json As JSONGenerator
    json.Initialize(PresenceData.Joins)
    Log("Joins: " & json.ToString)
    
    json.Initialize(PresenceData.Leaves)
    Log("Leaves: " & json.ToString)
    
End Sub