Add Paths Person API dropoff functionality

ee/clickhouse/queries/paths/paths_persons.py

@@ -8,15 +8,19 @@
 
 class ClickhousePathsPersons(ClickhousePaths):
     """    
-    `path_start_key` and `path_end_key` are two new params for this class.
-    These determine the start and end point of Paths you want. Both of these are optional.
+    `path_start_key`, `path_end_key`, and `path_dropoff_key` are three new params for this class.
+    These determine the start and end point of Paths you want. All of these are optional.
 
     Not specifying them means "get me all users on this path query".
 
     Only specifying `path_start_key` means "get me all users whose paths start at this key"
     Only specifying `path_end_key` means "get me all users whose paths end at this key"
 
     Specifying both means "get me all users whose path starts at `start_key` and ends at `end_key`."
+
+    Specifying `path_dropoff_key` means "get me users who dropped off after this key. If you specify
+    this key, the other two keys are invalid
+
     Note that:
         Persons are calculated only between direct paths. There should not be any
         other path item between start and end key.
@@ -48,13 +52,18 @@ def get_query(self):
 
     def get_person_path_filter(self) -> str:
         conditions = []
-        if self._filter.path_start_key:
-            conditions.append("last_path_key = %(path_start_key)s")
-            self.params["path_start_key"] = self._filter.path_start_key
 
-        if self._filter.path_end_key:
-            conditions.append("path_key = %(path_end_key)s")
-            self.params["path_end_key"] = self._filter.path_end_key
+        if self._filter.path_dropoff_key:
+            conditions.append("path_dropoff_key = %(path_dropoff_key)s")
+            self.params["path_dropoff_key"] = self._filter.path_dropoff_key
+        else:
+            if self._filter.path_start_key:
+                conditions.append("last_path_key = %(path_start_key)s")
+                self.params["path_start_key"] = self._filter.path_start_key
+
+            if self._filter.path_end_key:
+                conditions.append("path_key = %(path_end_key)s")
+                self.params["path_end_key"] = self._filter.path_end_key
 
         if conditions:
             return " AND ".join(conditions)

ee/clickhouse/queries/test/test_paths.py

@@ -35,8 +35,10 @@ class TestClickhousePaths(ClickhouseTestMixin, paths_test_factory(ClickhousePath
 
     maxDiff = None
 
-    def _get_people_at_path(self, filter, path_start, path_end, funnel_filter=None):
-        person_filter = filter.with_data({"path_start_key": path_start, "path_end_key": path_end})
+    def _get_people_at_path(self, filter, path_start=None, path_end=None, funnel_filter=None, path_dropoff=None):
+        person_filter = filter.with_data(
+            {"path_start_key": path_start, "path_end_key": path_end, "path_dropoff_key": path_dropoff}
+        )
         result = ClickhousePathsPersons(person_filter, self.team, funnel_filter)._exec_query()
         return [row[0] for row in result]
 
@@ -1494,3 +1496,51 @@ def test_path_grouping_with_evil_input(self):
                 {"source": "2_/2/bar/aaa", "target": "3_/3*", "value": 1, "average_conversion_time": 2 * ONE_MINUTE},
             ],
         )
+
+    def test_paths_person_dropoffs(self):
+
+        # 5 people do 2 events
+        for i in range(5):
+            Person.objects.create(distinct_ids=[f"user_{i}"], team=self.team)
+            _create_event(event="step one", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:00:00")
+            _create_event(event="step two", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:04:00")
+
+        # 10 people do 3 events
+        for i in range(5, 15):
+            Person.objects.create(distinct_ids=[f"user_{i}"], team=self.team)
+            _create_event(event="step one", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:00:00")
+            _create_event(event="step two", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:04:00")
+            _create_event(event="step three", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:05:00")
+
+        # 20 people do 4 events
+        for i in range(15, 35):
+            Person.objects.create(distinct_ids=[f"user_{i}"], team=self.team)
+            _create_event(event="step one", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:00:00")
+            _create_event(event="step two", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:04:00")
+            _create_event(event="step three", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:05:00")
+            _create_event(event="step four", distinct_id=f"user_{i}", team=self.team, timestamp="2021-05-01 00:06:00")
+
+        filter = PathFilter(
+            data={
+                "include_event_types": ["custom_event"],
+                "date_from": "2021-05-01 00:00:00",
+                "date_to": "2021-05-07 00:00:00",
+            }
+        )
+        self.assertEqual(5, len(self._get_people_at_path(filter, path_dropoff="2_step two")))  # 5 dropoff at step 2
+        self.assertEqual(35, len(self._get_people_at_path(filter, path_end="2_step two")))  # 35 total reach step 2
+        self.assertEqual(
+            30, len(self._get_people_at_path(filter, path_start="2_step two"))
+        )  # 30 total reach after step 2
+
+        self.assertEqual(10, len(self._get_people_at_path(filter, path_dropoff="3_step three")))  # 10 dropoff at step 3
+        self.assertEqual(30, len(self._get_people_at_path(filter, path_end="3_step three")))  # 30 total reach step 3
+        self.assertEqual(
+            20, len(self._get_people_at_path(filter, path_start="3_step three"))
+        )  # 20 total reach after step 3
+
+        self.assertEqual(20, len(self._get_people_at_path(filter, path_dropoff="4_step four")))  # 20 dropoff at step 4
+        self.assertEqual(20, len(self._get_people_at_path(filter, path_end="4_step four")))  # 20 total reach step 4
+        self.assertEqual(
+            0, len(self._get_people_at_path(filter, path_start="4_step four"))
+        )  # 0 total reach after step 4

ee/clickhouse/sql/paths/path.py

@@ -4,7 +4,8 @@
             conversion_time,
             event_in_session_index,
             concat(toString(event_in_session_index), '_', path) as path_key,
-            if(event_in_session_index > 1, neighbor(path_key, -1), null) AS last_path_key
+            if(event_in_session_index > 1, neighbor(path_key, -1), null) AS last_path_key,
+            path_dropoff_key
         FROM (
 
             SELECT person_id
@@ -19,6 +20,7 @@
                 {target_clause}
                 , arrayDifference(limited_timings) as timings_diff
                 , arrayZip(limited_path, timings_diff) as limited_path_timings
+                , concat(toString(length(limited_path)), '_', limited_path[-1]) as path_dropoff_key /* last path item */
             FROM (
                 SELECT person_id
                     , path_time_tuple.1 as path_basic

posthog/constants.py

@@ -126,6 +126,7 @@ class AvailableFeature(str, Enum):
 PATH_GROUPINGS = "path_groupings"
 PATH_START_KEY = "path_start_key"
 PATH_END_KEY = "path_end_key"
+PATH_DROPOFF_KEY = "path_dropoff_key"
 
 
 class FunnelOrderType(str, Enum):

posthog/models/filters/mixins/paths.py

@@ -6,6 +6,7 @@
     END_POINT,
     FUNNEL_PATHS,
     PAGEVIEW_EVENT,
+    PATH_DROPOFF_KEY,
     PATH_END_KEY,
     PATH_GROUPINGS,
     PATH_START_KEY,
@@ -165,11 +166,15 @@ def path_groupings_to_dict(self):
 class PathPersonsMixin(BaseParamMixin):
     @cached_property
     def path_start_key(self) -> Optional[str]:
-        return self._data.get(PATH_START_KEY, None)
+        return self._data.get(PATH_START_KEY)
 
     @cached_property
     def path_end_key(self) -> Optional[str]:
-        return self._data.get(PATH_END_KEY, None)
+        return self._data.get(PATH_END_KEY)
+
+    @cached_property
+    def path_dropoff_key(self) -> Optional[str]:
+        return self._data.get(PATH_DROPOFF_KEY)
 
     @include_dict
     def path_start_end_to_dict(self):
@@ -180,4 +185,7 @@ def path_start_end_to_dict(self):
         if self.path_end_key:
             result[PATH_END_KEY] = self.path_end_key
 
+        if self.path_dropoff_key:
+            result[PATH_DROPOFF_KEY] = self.path_dropoff_key
+
         return result