Android Example [B4X] Supabase - Realtime Postgres Changes

[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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Listen to Postgres changes using Supabase Realtime.

Postgres Changes | Supabase Docs

Listen to Postgres changes using Supabase Realtime.

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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Listening to ALL events

    Realtime _
    .Channel("public","dt_Chat","") _
    .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_ALL) _
    .Subscribe 'subscribe to a topic - In this example we subscibe to all database changes on dt_Tasks

    Wait For Realtime_Subscribed 'Successfully subscribed
    Log("Subscribed to topic")

Listening to INSERT events

    Realtime _
    .Channel("public","dt_Chat","") _
    .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_INSERT) _
    .Subscribe

Listening to UPDATE events

    Realtime _
    .Channel("public","dt_Chat","") _
    .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_UPDATE) _
    .Subscribe

Listening to DELETE events

    Realtime _
    .Channel("public","dt_Chat","") _
    .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_DELETE) _
    .Subscribe

Listening to multiple changes

    Realtime _
    .Channel("public","dt_Chat","") _
    .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_INSERT) _
     .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_UPDATE) _
    .Subscribe

Filtering for specific changes
Filters are there to react only to certain changes. e.g. we want to have only all changes from the chat room with id 3.
In the following example we subscribe to all database changes with room_id = 3

    Realtime _
    .Channel("public","dt_Chat",Realtime.BuildFilter("room_id",Realtime.Filter_Equal,"3")) _
    .On(Realtime.SubscribeType_PostgresChanges) _
    .Event(Realtime.Event_ALL) _
    .Subscribe

Events

Private Sub Realtime_DataReceived(Data As SupabaseRealtime_Data)
 
    If Data.EventType = Realtime.Event_UPDATE Then 'A record in the database was changed
 
        For Each k As String In Data.Records.Keys
            Log($"Column: "${k}" Value: "${Data.Records.Get(k)}""$)
        Next
 
    End If
 
End Sub