From 52a7aea09dcdb1c04542cc9b441ea241ccb2e2e3 Mon Sep 17 00:00:00 2001
From: Michael Matloka <michal@matloka.com>
Date: Tue, 3 Oct 2023 23:30:04 +0200
Subject: [PATCH] fix(capture): Always update stored person props from $set

---
 src/__tests__/posthog-core.js | 17 +++++++++++++++++
 src/posthog-core.ts           |  8 ++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/__tests__/posthog-core.js b/src/__tests__/posthog-core.js
index 4991c86cb..3afe3a190 100644
--- a/src/__tests__/posthog-core.js
+++ b/src/__tests__/posthog-core.js
@@ -43,6 +43,11 @@ describe('capture()', () => {
             remove_event_timer: jest.fn(),
             properties: jest.fn(),
             update_config: jest.fn(),
+            register(properties) {
+                // Simplified version of the real thing
+                Object.assign(this.props, properties)
+            },
+            props: {},
         },
         sessionPersistence: {
             update_search_keyword: jest.fn(),
@@ -169,6 +174,18 @@ describe('capture()', () => {
         )
     })
 
+    it('updates persisted person properties for feature flags if $set is present', () => {
+        given('config', () => ({
+            property_blacklist: [],
+            _onCapture: jest.fn(),
+        }))
+        given('eventProperties', () => ({
+            $set: { foo: 'bar' },
+        }))
+        given.subject()
+        expect(given.overrides.persistence.props.$stored_person_properties).toMatchObject({ foo: 'bar' })
+    })
+
     it('correctly handles the "length" property', () => {
         const captureResult = given.lib.capture('event-name', { foo: 'bar', length: 0 })
         expect(captureResult.properties).toEqual(expect.objectContaining({ foo: 'bar', length: 0 }))
diff --git a/src/posthog-core.ts b/src/posthog-core.ts
index 58b39b775..9f8dbf11d 100644
--- a/src/posthog-core.ts
+++ b/src/posthog-core.ts
@@ -7,6 +7,7 @@ import {
     _info,
     _isArray,
     _isBlockedUA,
+    _isEmptyObject,
     _isObject,
     _isUndefined,
     _register_event,
@@ -881,6 +882,13 @@ export class PostHog {
         data = _copyAndTruncateStrings(data, options._noTruncate ? null : this.config.properties_string_max_length)
         data.timestamp = options.timestamp || new Date()
 
+        // Top-level $set overriding values from the one from properties is taken from the plugin-server normalizeEvent
+        // This doesn't handle $set_once, because posthog-people doesn't either
+        const finalSet = { ...data.properties['$set'], ...data['$set'] }
+        if (!_isEmptyObject(finalSet)) {
+            this.setPersonPropertiesForFlags(finalSet)
+        }
+
         if (this.config.debug) {
             logger.log('PostHog.js send', data)
         }