fix!: Document.has_value_changed returns Truthy or False

- Return changed value to avoid re-accessing previous object & it's
   attribute
 - Wrap returned value as Truthy to avoid breaking change in API

frappe/core/doctype/server_script/server_script.py

@@ -115,7 +115,7 @@ class ServerScript(Document):
 		if self.script_type != "Scheduler Event" or (
 			(previous_script_type := self.has_value_changed("script_type"))
 			# True will be sent if its a new record
-			and previous_script_type not in (True, "Scheduler Event")
+			and previous_script_type.value not in (True, "Scheduler Event")
 		):
 			return
 

frappe/model/document.py

@@ -21,7 +21,7 @@ from frappe.model.naming import set_new_name, validate_name
 from frappe.model.utils import is_virtual_doctype
 from frappe.model.workflow import set_workflow_state_on_action, validate_workflow
 from frappe.types import DF
-from frappe.utils import compare, cstr, date_diff, file_lock, flt, now
+from frappe.utils import Truthy, compare, cstr, date_diff, file_lock, flt, now
 from frappe.utils.data import get_absolute_url, get_datetime, get_timedelta, getdate
 from frappe.utils.global_search import update_global_search
 
@@ -468,7 +468,7 @@ class Document(BaseDocument):
 		previous = self.get_doc_before_save()
 
 		if not previous:
-			return True
+			return Truthy(context="New Document")
 
 		previous_value = previous.get(fieldname)
 		current_value = self.get(fieldname)
@@ -480,7 +480,10 @@ class Document(BaseDocument):
 		elif isinstance(previous_value, timedelta):
 			current_value = get_timedelta(current_value)
 
-		return previous_value != current_value
+		if previous_value != current_value:
+			return Truthy(value=previous_value)
+
+		return False
 
 	def set_new_name(self, force=False, set_name=None, set_child_names=True):
 		"""Calls `frappe.naming.set_new_name` for parent and child docs."""

frappe/utils/__init__.py

@@ -42,6 +42,8 @@ EMAIL_MATCH_PATTERN = re.compile(
 	re.IGNORECASE,
 )
 
+UNSET = object()
+
 
 def get_fullname(user=None):
 	"""get the full name (first name + last name) of the user from User"""
@@ -1166,3 +1168,18 @@ class CallbackManager:
 
 	def reset(self):
 		self._functions.clear()
+
+
+class Truthy:
+	def __init__(self, value=UNSET, context=UNSET):
+		self.value = value
+		self.context = context
+
+	def __bool__(self):
+		return True
+
+	def __repr__(self) -> str:
+		_val = "UNSET" if self.value is UNSET else self.value
+		_ctx = "UNSET" if self.context is UNSET else self.context
+
+		return f"Truthy(value={_val}, context={_ctx})"