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Supabase Backend as a Service · Pelajaran

Berlangganan Perubahan Tabel

Terapkan kode sisi klien untuk mendengarkan penyisipan, pembaruan, dan penghapusan pada tabel atau baris basis data tertentu.

Berlangganan Perubahan Tabel adalah pelajaran Supabase Backend as a Service gratis di CoddyKit. Ini adalah pelajaran 2 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Supabase Backend as a Service, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Supabase Backend as a Service mencakup 4 pelajaran total.

Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.

Welcome to Live Data!

In the previous lesson, we learned about the idea of realtime data. Now, let's dive into how your app can actually listen for changes happening in your Supabase database!

This means your users can see updates instantly, without refreshing their screen. Think live chat, notifications, or dashboards.

The Realtime Client

Supabase provides a powerful Realtime client that makes listening for database changes super easy. It's built on PostgreSQL's replication features.

  • It uses WebSockets for instant communication.
  • You'll interact with it through the supabase.realtime object.
  • It works by connecting to specific 'channels'.

Creating a Channel

Before listening to changes, you need to create a channel. A channel is like a dedicated line for receiving updates from your database.

You specify which table you're interested in, and then you can subscribe to events on that table.

import { createClient } from '@supabase/supabase-js';

const SUPABASE_URL = 'YOUR_SUPABASE_URL';
const SUPABASE_ANON_KEY = 'YOUR_ANON_KEY';

const supabase = createClient(SUPABASE_URL, SUPABASE_ANON_KEY);

// Create a channel for the 'messages' table
const messagesChannel = supabase.channel('table-db-changes')
  .on(
    'postgres_changes',
    { event: '*', schema: 'public', table: 'messages' },
    (payload) => {
      console.log('Change received!', payload);
    }
  )
  .subscribe();

console.log('Subscribed to messages channel...');

// In a real app, you'd keep this running to listen.
// For this example, we'll just show the setup.
// You'd typically unsubscribe when the component unmounts.
// messagesChannel.unsubscribe();

Listening for All Events

The example above uses event: '*'. This is a wildcard that tells Supabase you want to be notified about all types of changes to your specified table.

  • INSERT: A new row was added.
  • UPDATE: An existing row was modified.
  • DELETE: A row was removed.

Each event type will trigger your callback function.

Code: All Table Changes

Let's refine our channel setup to explicitly listen for all event types on a products table. Imagine we're building an inventory app!

Run this code and imagine new products being added, updated, or deleted.

import { createClient } from '@supabase/supabase-js';

const SUPABASE_URL = 'YOUR_SUPABASE_URL';
const SUPABASE_ANON_KEY = 'YOUR_ANON_KEY';

const supabase = createClient(SUPABASE_URL, SUPABASE_ANON_KEY);

const productChanges = supabase.channel('product_updates')
  .on(
    'postgres_changes',
    { event: '*', schema: 'public', table: 'products' },
    (payload) => {
      console.log('Product change detected:', payload.eventType);
      console.log('New data:', payload.new);
      console.log('Old data:', payload.old);
    }
  )
  .subscribe();

console.log('Listening for all changes on products table...');

// This script would typically run in a browser or Node.js environment
// where Supabase client is properly initialized and events would stream.
// For this interactive example, it shows the setup.
// In a real scenario, you'd wait for actual database events.

Targeting Specific Events

Sometimes you only care about certain types of changes. For instance, maybe you only want to know when a new item is added, not when it's updated or deleted.

You can specify the event type in your subscription options:

  • event: 'INSERT'
  • event: 'UPDATE'
  • event: 'DELETE'

Filtering by Row Data

Beyond event types, you can also filter updates based on the data within the rows themselves. This is super powerful for listening to changes on specific records!

Use conditions like eq (equals) or neq (not equals) on column values:

  • filter: 'id=eq.123' (Listen for changes to row with ID 123)
  • filter: 'status=neq.archived' (Listen for changes where status is NOT archived)

Code: Filtered Changes

Let's set up a subscription that only listens for new products being added (INSERT) AND only if their category is 'electronics'.

Run this and see how specific you can get!

import { createClient } from '@supabase/supabase-js';

const SUPABASE_URL = 'YOUR_SUPABASE_URL';
const SUPABASE_ANON_KEY = 'YOUR_ANON_KEY';

const supabase = createClient(SUPABASE_URL, SUPABASE_ANON_KEY);

const newElectronics = supabase.channel('new_electronics_channel')
  .on(
    'postgres_changes',
    {
      event: 'INSERT',
      schema: 'public',
      table: 'products',
      filter: 'category=eq.electronics' // Filter by category
    },
    (payload) => {
      console.log('New electronic product added:', payload.new.name);
      console.log('Details:', payload.new);
    }
  )
  .subscribe();

console.log('Listening for new electronic products...');

// This code demonstrates the filter setup.
// Actual events would be logged if matching data is inserted.

Handling Incoming Data

When an event occurs, your callback function receives a payload object. This object contains all the details about the change:

  • eventType: 'INSERT', 'UPDATE', or 'DELETE'.
  • new: The new row data (for INSERT/UPDATE).
  • old: The old row data (for UPDATE/DELETE).
  • table, schema: Info about where the change occurred.

This data lets you update your UI or trigger other logic.

Unsubscribing from Changes

It's important to unsubscribe from channels when they are no longer needed. This prevents memory leaks and unnecessary network traffic.

In a React component, you might unsubscribe in the componentWillUnmount or a useEffect cleanup function. Just call .unsubscribe() on your channel object.

const myChannel = supabase.channel('my_channel')
  .on(...)
  .subscribe();

// Later, when you're done listening:
myChannel.unsubscribe();
console.log('Unsubscribed from my_channel.');

Quick Check: Realtime Filters

You want to listen for any updates to the orders table, specifically for orders where the status changes to 'shipped'.

Which options would you use in your on() method?

Recap: Stay Updated!

Great job! You've learned how to harness Supabase Realtime to listen for live database changes.

  • You create a channel for a specific table.
  • You use .on('postgres_changes', options, callback) to subscribe.
  • You can filter by event type (INSERT, UPDATE, DELETE) and by row data (e.g., filter: 'column=eq.value').
  • Always remember to unsubscribe when a channel is no longer needed.

Next, we'll build a live chat feature using these concepts!

Pertanyaan yang Sering Diajukan

Apakah pelajaran “Berlangganan Perubahan Tabel” gratis?

Ya — teks lengkap “Berlangganan Perubahan Tabel” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Supabase Backend as a Service, upgrade ke CoddyKit PRO. Kursus Supabase Backend as a Service mencakup 4 pelajaran total.

Apa yang akan aku pelajari di “Berlangganan Perubahan Tabel”?

Terapkan kode sisi klien untuk mendengarkan penyisipan, pembaruan, dan penghapusan pada tabel atau baris basis data tertentu. Kamu berlatih Supabase Backend as a Service dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.

Apakah aku perlu pengalaman untuk memulai Supabase Backend as a Service?

Tidak diperlukan pengalaman sebelumnya. Supabase Backend as a Service di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 2 dari 4.

Berapa lama pelajaran “Berlangganan Perubahan Tabel” memakan waktu?

Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.

Bisakah aku menulis dan menjalankan kode dalam pelajaran Supabase Backend as a Service ini?

Ya. Setiap pelajaran Supabase Backend as a Service menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.

Semua pelajaran dalam kursus ini

  1. Memahami Langganan Waktu Nyata
  2. Berlangganan Perubahan Tabel
  3. Membangun Fitur Obrolan Langsung
  4. Saluran Kehadiran dan Siaran
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