fix(realtime): handle null values in postgres changes filter comparison (#1918)

Author: 7ttp

packages/core/realtime-js/src/RealtimeChannel.ts

@@ -330,9 +330,9 @@ export default class RealtimeChannel {
               if (
                 serverPostgresFilter &&
                 serverPostgresFilter.event === event &&
-                serverPostgresFilter.schema === schema &&
-                serverPostgresFilter.table === table &&
-                serverPostgresFilter.filter === filter
+                RealtimeChannel.isFilterValueEqual(serverPostgresFilter.schema, schema) &&
+                RealtimeChannel.isFilterValueEqual(serverPostgresFilter.table, table) &&
+                RealtimeChannel.isFilterValueEqual(serverPostgresFilter.filter, filter)
               ) {
                 newPostgresBindings.push({
                   ...clientPostgresBinding,
@@ -952,6 +952,20 @@ export default class RealtimeChannel {
     return true
   }
 
+  /**
+   * Compares two optional filter values for equality.
+   * Treats undefined, null, and empty string as equivalent empty values.
+   * @internal
+   */
+  private static isFilterValueEqual(
+    serverValue: string | undefined | null,
+    clientValue: string | undefined
+  ): boolean {
+    const normalizedServer = serverValue ?? undefined
+    const normalizedClient = clientValue ?? undefined
+    return normalizedServer === normalizedClient
+  }
+
   /** @internal */
   private _rejoinUntilConnected() {
     this.rejoinTimer.scheduleTimeout()

packages/core/realtime-js/test/RealtimeChannel.postgres.test.ts

@@ -247,6 +247,77 @@ describe('PostgreSQL binding matching behavior', () => {
     assert.equal(channel.bindings.postgres_changes[0].id, 'server-id-1')
   })
 
+  test('should match postgres changes when server returns null for optional fields', () => {
+    const callbackSpy = vi.fn()
+
+    channel.on(
+      'postgres_changes',
+      {
+        event: 'INSERT',
+        schema: 'public',
+        table: 'notifications',
+      },
+      callbackSpy
+    )
+
+    channel.subscribe()
+
+    const mockServerResponse = {
+      postgres_changes: [
+        {
+          event: 'INSERT',
+          schema: 'public',
+          table: 'notifications',
+          filter: null,
+          id: 'server-id-1',
+        },
+      ],
+    }
+
+    channel.joinPush._matchReceive({
+      status: 'ok',
+      response: mockServerResponse,
+    })
+
+    assert.equal(channel.state, CHANNEL_STATES.joined)
+    assert.equal(channel.bindings.postgres_changes[0].id, 'server-id-1')
+  })
+
+  test('should match postgres changes when server omits optional filter field', () => {
+    const callbackSpy = vi.fn()
+
+    channel.on(
+      'postgres_changes',
+      {
+        event: '*',
+        schema: 'public',
+        table: 'notifications',
+      },
+      callbackSpy
+    )
+
+    channel.subscribe()
+
+    const mockServerResponse = {
+      postgres_changes: [
+        {
+          event: '*',
+          schema: 'public',
+          table: 'notifications',
+          id: 'server-id-1',
+        },
+      ],
+    }
+
+    channel.joinPush._matchReceive({
+      status: 'ok',
+      response: mockServerResponse,
+    })
+
+    assert.equal(channel.state, CHANNEL_STATES.joined)
+    assert.equal(channel.bindings.postgres_changes[0].id, 'server-id-1')
+  })
+
   test.each([
     {
       description: 'should fail when event differs',