feat(django): allow elements chain as string for certain teams (#18701)

* Adding flag in decide response to allow returning elements chain as a string; related PR: PostHog/posthog-js#823

* Created a separate env var to control this behavior in https://github.com/PostHog/posthog-cloud-infra/pull/2314

* Update query snapshots

* Add env var

* Update query snapshots

* Formatting

* Just use a boolean

* Add test for when ELEMENT_CHAIN_AS_STRING_TEAMS is set and not set

* Fix test

---------

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

posthog/api/decide.py

@@ -230,6 +230,9 @@ def get_decide(request: HttpRequest):
                     if random() < settings.NEW_ANALYTICS_CAPTURE_SAMPLING_RATE:
                         response["analytics"] = {"endpoint": settings.NEW_ANALYTICS_CAPTURE_ENDPOINT}
 
+            if settings.ELEMENT_CHAIN_AS_STRING_TEAMS and str(team.id) in settings.ELEMENT_CHAIN_AS_STRING_TEAMS:
+                response["elementsChainAsString"] = True
+
             if team.session_recording_opt_in and (
                 on_permitted_recording_domain(team, request) or not team.recording_domains
             ):

posthog/api/test/test_decide.py

@@ -3006,6 +3006,19 @@ def test_decide_new_capture_activation(self, *args):
             self.assertEqual(response.status_code, 200)
             self.assertFalse("analytics" in response.json())
 
+    def test_decide_element_chain_as_string(self, *args):
+        self.client.logout()
+        with self.settings(ELEMENT_CHAIN_AS_STRING_TEAMS={str(self.team.id)}):
+            response = self._post_decide(api_version=3)
+            self.assertEqual(response.status_code, 200)
+            self.assertTrue("elementsChainAsString" in response.json())
+            self.assertTrue(response.json()["elementsChainAsString"])
+
+        with self.settings(ELEMENT_CHAIN_AS_STRING_TEAMS={"0"}):
+            response = self._post_decide(api_version=3)
+            self.assertEqual(response.status_code, 200)
+            self.assertFalse("elementsChainAsString" in response.json())
+
 
 class TestDatabaseCheckForDecide(BaseTest, QueryMatchingTest):
     """

posthog/settings/ingestion.py

@@ -38,3 +38,5 @@
 NEW_ANALYTICS_CAPTURE_TEAM_IDS = get_set(os.getenv("NEW_ANALYTICS_CAPTURE_TEAM_IDS", ""))
 NEW_ANALYTICS_CAPTURE_EXCLUDED_TEAM_IDS = get_set(os.getenv("NEW_ANALYTICS_CAPTURE_EXCLUDED_TEAM_IDS", ""))
 NEW_ANALYTICS_CAPTURE_SAMPLING_RATE = get_from_env("NEW_ANALYTICS_CAPTURE_SAMPLING_RATE", type_cast=float, default=1.0)
+
+ELEMENT_CHAIN_AS_STRING_TEAMS = get_set(os.getenv("ELEMENT_CHAIN_AS_STRING_TEAMS", ""))