From ecd47719e3b95547f268aef94aa104e32c0bfa1c Mon Sep 17 00:00:00 2001
From: Tiina Turban <tiina303@gmail.com>
Date: Wed, 27 Sep 2023 18:08:24 +0200
Subject: [PATCH] chore: Ignore {} unset value instead of DLQ the event
 (#17633)

---
 .../src/worker/ingestion/person-state.ts      |  5 +++-
 .../tests/main/process-event.test.ts          | 29 +++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/plugin-server/src/worker/ingestion/person-state.ts b/plugin-server/src/worker/ingestion/person-state.ts
index 72a82a07d0aec..16cae0d5e1a1e 100644
--- a/plugin-server/src/worker/ingestion/person-state.ts
+++ b/plugin-server/src/worker/ingestion/person-state.ts
@@ -226,7 +226,10 @@ export class PersonState {
 
         const properties: Properties = this.eventProperties['$set'] || {}
         const propertiesOnce: Properties = this.eventProperties['$set_once'] || {}
-        const unsetProperties: Array<string> = this.eventProperties['$unset'] || []
+        const unsetProps = this.eventProperties['$unset']
+        const unsetProperties: Array<string> = Array.isArray(unsetProps)
+            ? unsetProps
+            : Object.keys(unsetProps || {}) || []
 
         // Figure out which properties we are actually setting
         Object.entries(propertiesOnce).map(([key, value]) => {
diff --git a/plugin-server/tests/main/process-event.test.ts b/plugin-server/tests/main/process-event.test.ts
index 94505831b8452..23b90c84fc5c9 100644
--- a/plugin-server/tests/main/process-event.test.ts
+++ b/plugin-server/tests/main/process-event.test.ts
@@ -2791,6 +2791,35 @@ test('$unset person property', async () => {
     expect(person.properties).toEqual({ b: 2 })
 })
 
+test('$unset person empty set ignored', async () => {
+    await createPerson(hub, team, ['distinct_id1'], { a: 1, b: 2, c: 3 })
+
+    await processEvent(
+        'distinct_id1',
+        '',
+        '',
+        {
+            event: 'some_event',
+            properties: {
+                token: team.api_token,
+                distinct_id: 'distinct_id1',
+                $unset: {},
+            },
+        } as any as PluginEvent,
+        team.id,
+        now,
+        new UUIDT().toString()
+    )
+    expect((await hub.db.fetchEvents()).length).toBe(1)
+
+    const [event] = await hub.db.fetchEvents()
+    expect(event.properties['$unset']).toEqual({})
+
+    const [person] = await hub.db.fetchPersons()
+    expect(await hub.db.fetchDistinctIdValues(person)).toEqual(['distinct_id1'])
+    expect(person.properties).toEqual({ a: 1, b: 2, c: 3 })
+})
+
 describe('ingestion in any order', () => {
     const ts0: DateTime = now
     const ts1: DateTime = now.plus({ minutes: 1 })