From 5e9439dffce9ec8ed182f814662fc60d21f3e0f9 Mon Sep 17 00:00:00 2001
From: Harry Waye <harry@microwayes.net>
Date: Wed, 17 May 2023 07:56:22 +0100
Subject: [PATCH] fix(identify): actually send $set_once on identify calls
 (#629)

We were handling $set but not $set_once. This fixes that.

Fixes #615
---
 src/__tests__/posthog-core.js | 22 ++++++++++++++++++++++
 src/posthog-core.ts           |  3 ++-
 src/types.ts                  |  1 +
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/__tests__/posthog-core.js b/src/__tests__/posthog-core.js
index 7840407e1..400906800 100644
--- a/src/__tests__/posthog-core.js
+++ b/src/__tests__/posthog-core.js
@@ -129,6 +129,28 @@ describe('capture()', () => {
         const event = given.subject()
         expect(event.properties.key.length).toBe(50000)
     })
+
+    it('passes through $set and $set_once into the request, if the event is an $identify event', () => {
+        // NOTE: this is slightly unusual to test capture for this specific case
+        // of being called with $identify as the event name. It might be that we
+        // decide that this shouldn't be a special case of capture in this case,
+        // but I'll add the case to capture current functionality.
+        //
+        // We check that if identify is called with user $set and $set_once
+        // properties, we also want to ensure capture does the expected thing
+        // with them.
+        const captureResult = given.lib.capture(
+            '$identify',
+            { distinct_id: 'some-distinct-id' },
+            { $set: { email: 'john@example.com' }, $set_once: { howOftenAmISet: 'once!' } }
+        )
+
+        // We assume that the returned result is the object we would send to the
+        // server.
+        expect(captureResult).toEqual(
+            expect.objectContaining({ $set: { email: 'john@example.com' }, $set_once: { howOftenAmISet: 'once!' } })
+        )
+    })
 })
 
 describe('_calculate_event_properties()', () => {
diff --git a/src/posthog-core.ts b/src/posthog-core.ts
index 6aec9b05c..8f8957b02 100644
--- a/src/posthog-core.ts
+++ b/src/posthog-core.ts
@@ -846,8 +846,9 @@ export class PostHog {
             properties: this._calculate_event_properties(event_name, properties || {}),
         }
 
-        if (event_name === '$identify' && options.$set) {
+        if (event_name === '$identify') {
             data['$set'] = options['$set']
+            data['$set_once'] = options['$set_once']
         }
 
         data = _copyAndTruncateStrings(
diff --git a/src/types.ts b/src/types.ts
index 332d0e3d3..a010c7180 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -9,6 +9,7 @@ export interface CaptureResult {
     event: string
     properties: Properties
     $set?: Properties
+    $set_once?: Properties
     timestamp?: Date
 }
 export type CaptureCallback = (response: any, data: any) => void