fix: only execute generator if value is not found in redis cache (#18472) (#18479)

* fix: use of generator in

* fix: improve docstring

* fix: improve docstring

* fix: directly assign value to flags

Co-authored-by: Daizy <DaizyModi>
(cherry picked from commit fce9ccedaa)

Co-authored-by: Daizy Modi <54097382+DaizyModi@users.noreply.github.com>

frappe/model/document.py

@@ -953,15 +953,19 @@ class Document(BaseDocument):
 		from frappe.email.doctype.notification.notification import evaluate_alert
 
 		if self.flags.notifications is None:
-			alerts = frappe.cache().hget("notifications", self.doctype)
-			if alerts is None:
-				alerts = frappe.get_all(
+
+			def _get_notifications():
+				"""returns enabled notifications for the current doctype"""
+
+				return frappe.get_all(
 					"Notification",
 					fields=["name", "event", "method"],
 					filters={"enabled": 1, "document_type": self.doctype},
 				)
-				frappe.cache().hset("notifications", self.doctype, alerts)
-			self.flags.notifications = alerts
+
+			self.flags.notifications = frappe.cache().hget(
+				"notifications", self.doctype, _get_notifications
+			)
 
 		if not self.flags.notifications:
 			return

frappe/utils/redis_wrapper.py

@@ -194,7 +194,7 @@ class RedisWrapper(redis.Redis):
 		except redis.exceptions.ConnectionError:
 			pass
 
-		if value:
+		if value is not None:
 			value = pickle.loads(value)
 			frappe.local.cache[_name][key] = value
 		elif generator: