feat(flags): Add local props and flags to all calls (#106)

Author: neilkakkar

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.3.0 - 2024-01-09
+
+1. When local evaluation is enabled, we automatically add flag information to all events sent to PostHog, whenever possible. This makes it easier to use these events in experiments.
+
 ## 3.2.0 - 2024-01-09
 
 1. Numeric property handling for feature flags now does the expected: When passed in a number, we do a numeric comparison. When passed in a string, we do a string comparison. Previously, we always did a string comparison.

posthog/client.py

@@ -213,8 +213,19 @@ def capture(
                 self.log.exception(f"[FEATURE FLAGS] Unable to get feature variants: {e}")
             else:
                 for feature, variant in feature_variants.items():
-                    msg["properties"]["$feature/{}".format(feature)] = variant
+                    msg["properties"][f"$feature/{feature}"] = variant
                 msg["properties"]["$active_feature_flags"] = list(feature_variants.keys())
+        elif self.feature_flags:
+            # Local evaluation is enabled, flags are loaded, so try and get all flags we can without going to the server
+            feature_variants = self.get_all_flags(
+                distinct_id, groups=(groups or {}), disable_geoip=disable_geoip, only_evaluate_locally=True
+            )
+            for feature, variant in feature_variants.items():
+                msg["properties"][f"$feature/{feature}"] = variant
+
+            active_feature_flags = [key for (key, value) in feature_variants.items() if value is not False]
+            if active_feature_flags:
+                msg["properties"]["$active_feature_flags"] = active_feature_flags
 
         return self._enqueue(msg, disable_geoip)
 
@@ -538,6 +549,10 @@ def get_feature_flag(
         if self.disabled:
             return None
 
+        person_properties, group_properties = self._add_local_person_and_group_properties(
+            distinct_id, groups, person_properties, group_properties
+        )
+
         if self.feature_flags is None and self.personal_api_key:
             self.load_feature_flags()
         response = None
@@ -685,6 +700,10 @@ def get_all_flags_and_payloads(
         if self.disabled:
             return {"featureFlags": None, "featureFlagPayloads": None}
 
+        person_properties, group_properties = self._add_local_person_and_group_properties(
+            distinct_id, groups, person_properties, group_properties
+        )
+
         flags, payloads, fallback_to_decide = self._get_all_flags_and_payloads_locally(
             distinct_id, groups=groups, person_properties=person_properties, group_properties=group_properties
         )
@@ -743,6 +762,19 @@ def _get_all_flags_and_payloads_locally(self, distinct_id, *, groups={}, person_
     def feature_flag_definitions(self):
         return self.feature_flags
 
+    def _add_local_person_and_group_properties(self, distinct_id, groups, person_properties, group_properties):
+        all_person_properties = {"$current_distinct_id": distinct_id, **(person_properties or {})}
+
+        all_group_properties = {}
+        if groups:
+            for group_name in groups:
+                all_group_properties[group_name] = {
+                    "$group_key": groups[group_name],
+                    **(group_properties.get(group_name) or {}),
+                }
+
+        return all_person_properties, all_group_properties
+
 
 def require(name, field, data_type):
     """Require that the named `field` has the right `data_type`"""

posthog/test/test_client.py

@@ -105,6 +105,110 @@ def test_basic_capture_with_feature_flags(self, patch_decide):
 
         self.assertEqual(patch_decide.call_count, 1)
 
+    @mock.patch("posthog.client.decide")
+    def test_basic_capture_with_locally_evaluated_feature_flags(self, patch_decide):
+        patch_decide.return_value = {"featureFlags": {"beta-feature": "random-variant"}}
+        client = Client(FAKE_TEST_API_KEY, on_error=self.set_fail, personal_api_key=FAKE_TEST_API_KEY)
+
+        multivariate_flag = {
+            "id": 1,
+            "name": "Beta Feature",
+            "key": "beta-feature-local",
+            "is_simple_flag": False,
+            "active": True,
+            "rollout_percentage": 100,
+            "filters": {
+                "groups": [
+                    {
+                        "properties": [
+                            {"key": "email", "type": "person", "value": "test@posthog.com", "operator": "exact"}
+                        ],
+                        "rollout_percentage": 100,
+                    },
+                    {
+                        "rollout_percentage": 50,
+                    },
+                ],
+                "multivariate": {
+                    "variants": [
+                        {"key": "first-variant", "name": "First Variant", "rollout_percentage": 50},
+                        {"key": "second-variant", "name": "Second Variant", "rollout_percentage": 25},
+                        {"key": "third-variant", "name": "Third Variant", "rollout_percentage": 25},
+                    ]
+                },
+                "payloads": {"first-variant": "some-payload", "third-variant": {"a": "json"}},
+            },
+        }
+        basic_flag = {
+            "id": 1,
+            "name": "Beta Feature",
+            "key": "person-flag",
+            "is_simple_flag": True,
+            "active": True,
+            "filters": {
+                "groups": [
+                    {
+                        "properties": [
+                            {
+                                "key": "region",
+                                "operator": "exact",
+                                "value": ["USA"],
+                                "type": "person",
+                            }
+                        ],
+                        "rollout_percentage": 100,
+                    }
+                ],
+                "payloads": {"true": 300},
+            },
+        }
+        false_flag = {
+            "id": 1,
+            "name": "Beta Feature",
+            "key": "false-flag",
+            "is_simple_flag": True,
+            "active": True,
+            "filters": {
+                "groups": [
+                    {
+                        "properties": [],
+                        "rollout_percentage": 0,
+                    }
+                ],
+                "payloads": {"true": 300},
+            },
+        }
+        client.feature_flags = [multivariate_flag, basic_flag, false_flag]
+
+        success, msg = client.capture("distinct_id", "python test event")
+        client.flush()
+        self.assertTrue(success)
+        self.assertFalse(self.failed)
+
+        self.assertEqual(msg["event"], "python test event")
+        self.assertTrue(isinstance(msg["timestamp"], str))
+        self.assertIsNone(msg.get("uuid"))
+        self.assertEqual(msg["distinct_id"], "distinct_id")
+        self.assertEqual(msg["properties"]["$lib"], "posthog-python")
+        self.assertEqual(msg["properties"]["$lib_version"], VERSION)
+        self.assertEqual(msg["properties"]["$feature/beta-feature-local"], "third-variant")
+        self.assertEqual(msg["properties"]["$feature/false-flag"], False)
+        self.assertEqual(msg["properties"]["$active_feature_flags"], ["beta-feature-local"])
+        assert "$feature/beta-feature" not in msg["properties"]
+
+        self.assertEqual(patch_decide.call_count, 0)
+
+        # test that flags are not evaluated without local evaluation
+        client.feature_flags = []
+        success, msg = client.capture("distinct_id", "python test event")
+        client.flush()
+        self.assertTrue(success)
+        self.assertFalse(self.failed)
+        assert "$feature/beta-feature" not in msg["properties"]
+        assert "$feature/beta-feature-local" not in msg["properties"]
+        assert "$feature/false-flag" not in msg["properties"]
+        assert "$active_feature_flags" not in msg["properties"]
+
     @mock.patch("posthog.client.decide")
     def test_get_active_feature_flags(self, patch_decide):
         patch_decide.return_value = {
@@ -620,7 +724,7 @@ def test_disable_geoip_default_on_decide(self, patch_decide):
             timeout=10,
             distinct_id="some_id",
             groups={},
-            person_properties={},
+            person_properties={"$current_distinct_id": "some_id"},
             group_properties={},
             disable_geoip=True,
         )
@@ -632,7 +736,7 @@ def test_disable_geoip_default_on_decide(self, patch_decide):
             timeout=10,
             distinct_id="feature_enabled_distinct_id",
             groups={},
-            person_properties={},
+            person_properties={"$current_distinct_id": "feature_enabled_distinct_id"},
             group_properties={},
             disable_geoip=True,
         )
@@ -644,7 +748,7 @@ def test_disable_geoip_default_on_decide(self, patch_decide):
             timeout=10,
             distinct_id="all_flags_payloads_id",
             groups={},
-            person_properties={},
+            person_properties={"$current_distinct_id": "all_flags_payloads_id"},
             group_properties={},
             disable_geoip=False,
         )
@@ -660,3 +764,70 @@ def raise_effect():
         client.feature_flags = [{"key": "example", "is_simple_flag": False}]
 
         self.assertFalse(client.feature_enabled("example", "distinct_id"))
+
+    @mock.patch("posthog.client.decide")
+    def test_default_properties_get_added_properly(self, patch_decide):
+        patch_decide.return_value = {
+            "featureFlags": {"beta-feature": "random-variant", "alpha-feature": True, "off-feature": False}
+        }
+        client = Client(FAKE_TEST_API_KEY, on_error=self.set_fail, disable_geoip=False)
+        client.get_feature_flag(
+            "random_key",
+            "some_id",
+            groups={"company": "id:5", "instance": "app.posthog.com"},
+            person_properties={"x1": "y1"},
+            group_properties={"company": {"x": "y"}},
+        )
+        patch_decide.assert_called_with(
+            "random_key",
+            None,
+            timeout=10,
+            distinct_id="some_id",
+            groups={"company": "id:5", "instance": "app.posthog.com"},
+            person_properties={"$current_distinct_id": "some_id", "x1": "y1"},
+            group_properties={
+                "company": {"$group_key": "id:5", "x": "y"},
+                "instance": {"$group_key": "app.posthog.com"},
+            },
+            disable_geoip=False,
+        )
+
+        patch_decide.reset_mock()
+        client.get_feature_flag(
+            "random_key",
+            "some_id",
+            groups={"company": "id:5", "instance": "app.posthog.com"},
+            person_properties={"$current_distinct_id": "override"},
+            group_properties={
+                "company": {
+                    "$group_key": "group_override",
+                }
+            },
+        )
+        patch_decide.assert_called_with(
+            "random_key",
+            None,
+            timeout=10,
+            distinct_id="some_id",
+            groups={"company": "id:5", "instance": "app.posthog.com"},
+            person_properties={"$current_distinct_id": "override"},
+            group_properties={
+                "company": {"$group_key": "group_override"},
+                "instance": {"$group_key": "app.posthog.com"},
+            },
+            disable_geoip=False,
+        )
+
+        patch_decide.reset_mock()
+        # test nones
+        client.get_all_flags_and_payloads("some_id", groups={}, person_properties=None, group_properties=None)
+        patch_decide.assert_called_with(
+            "random_key",
+            None,
+            timeout=10,
+            distinct_id="some_id",
+            groups={},
+            person_properties={"$current_distinct_id": "some_id"},
+            group_properties={},
+            disable_geoip=False,
+        )

posthog/version.py

@@ -1,4 +1,4 @@
-VERSION = "3.2.0"
+VERSION = "3.3.0"
 
 if __name__ == "__main__":
     print(VERSION, end="")  # noqa: T201