From abaeabea22b18df4af76b2bd9030aea4cea52af0 Mon Sep 17 00:00:00 2001
From: Fabio Manganiello <fabio@manganiello.tech>
Date: Wed, 30 Nov 2022 00:50:53 +0100
Subject: [PATCH] Implemented recursive merges of parent/child relationships in
 entities

---
 platypush/entities/_engine.py | 87 ++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 41 deletions(-)

diff --git a/platypush/entities/_engine.py b/platypush/entities/_engine.py
index dfc57e16de..2780596a3f 100644
--- a/platypush/entities/_engine.py
+++ b/platypush/entities/_engine.py
@@ -167,9 +167,9 @@ class EntitiesEngine(Thread):
 
         self.logger.info('Stopped entities engine')
 
-    def _get_if_exist(
+    def get_if_exist(
         self, session: Session, entities: Iterable[Entity]
-    ) -> Iterable[Entity]:
+    ) -> List[Entity]:
         existing_entities = {
             (
                 str(entity.external_id)
@@ -211,50 +211,13 @@ class EntitiesEngine(Thread):
             for entity in entities
         ]
 
-    def _merge_entities(
-        self, entities: List[Entity], existing_entities: List[Entity]
-    ) -> List[Entity]:
-        def merge(entity: Entity, existing_entity: Entity) -> Entity:
-            columns = [col.key for col in entity.columns]
-            for col in columns:
-                if col == 'meta':
-                    existing_entity.meta = {  # type: ignore
-                        **(existing_entity.meta or {}),  # type: ignore
-                        **(entity.meta or {}),  # type: ignore
-                    }
-                elif col not in ('id', 'created_at'):
-                    setattr(existing_entity, col, getattr(entity, col))
-
-            return existing_entity
-
-        def entity_key(entity: Entity):
-            return ((entity.external_id or entity.name), entity.plugin)
-
-        new_entities = {}
-        entities_map = {}
-
-        # Get the latest update for each ((id|name), plugin) record
-        for e in entities:
-            entities_map[entity_key(e)] = e
-
-        # Retrieve existing records and merge them
-        for i, entity in enumerate(entities):
-            existing_entity = existing_entities[i]
-            if existing_entity:
-                entity = merge(entity, existing_entity)
-
-            new_entities[entity_key(entity)] = entity
-
-        return list(new_entities.values())
-
-    def _process_entities(self, *entities: Entity):
+    def _process_entities(self, *entities: Entity):  # type: ignore
         with self._get_session(locked=True) as session:
             # Ensure that the internal IDs are set to null before the merge
             for e in entities:
                 e.id = None  # type: ignore
 
-            existing_entities = self._get_if_exist(session, entities)
-            entities = self._merge_entities(entities, existing_entities)  # type: ignore
+            entities: List[Entity] = self._merge_entities(session, entities)
             session.add_all(entities)
             session.commit()
 
@@ -274,3 +237,45 @@ class EntitiesEngine(Thread):
             if e in entities_awaiting_flush:
                 self._process_event(entity)
                 self._entities_awaiting_flush.remove(e)
+
+    def _merge_entities(
+        self, session: Session, entities: Iterable[Entity]
+    ) -> List[Entity]:
+        existing_entities = self.get_if_exist(session, entities)
+        new_entities = {}
+        entities_map = {}
+
+        # Get the latest update for each ((id|name), plugin) record
+        for e in entities:
+            entities_map[self.entity_key(e)] = e
+
+        # Retrieve existing records and merge them
+        for i, entity in enumerate(entities):
+            existing_entity = existing_entities[i]
+            if existing_entity:
+                existing_entity.children = self._merge_entities(
+                    session, entity.children
+                )
+                entity = self._merge_entity_columns(entity, existing_entity)
+
+            new_entities[self.entity_key(entity)] = entity
+
+        return list(new_entities.values())
+
+    @classmethod
+    def _merge_entity_columns(cls, entity: Entity, existing_entity: Entity) -> Entity:
+        columns = [col.key for col in entity.columns]
+        for col in columns:
+            if col == 'meta':
+                existing_entity.meta = {  # type: ignore
+                    **(existing_entity.meta or {}),  # type: ignore
+                    **(entity.meta or {}),  # type: ignore
+                }
+            elif col not in ('id', 'created_at'):
+                setattr(existing_entity, col, getattr(entity, col))
+
+        return existing_entity
+
+    @staticmethod
+    def entity_key(entity: Entity):
+        return ((entity.external_id or entity.name), entity.plugin)