fix: datetime comparison in QB (#26364)

closes https://github.com/frappe/frappe/issues/26363

frappe/database/database.py

@@ -1105,7 +1105,7 @@ class Database:
 		"""Return True if at least one row exists."""
 		return frappe.get_all(doctype, limit=1, order_by=None, as_list=True)
 
-	def exists(self, dt, dn=None, cache=False):
+	def exists(self, dt, dn=None, cache=False, *, debug=False):
 		"""Return the document name of a matching document, or None.
 
 		Note: `cache` only works if `dt` and `dn` are of type `str`.
@@ -1138,7 +1138,7 @@ class Database:
 			dt = dt.copy()  # don't modify the original dict
 			dt, dn = dt.pop("doctype"), dt
 
-		return self.get_value(dt, dn, ignore=True, cache=cache, order_by=None)
+		return self.get_value(dt, dn, ignore=True, cache=cache, order_by=None, debug=debug)
 
 	def count(self, dt, filters=None, debug=False, cache=False, distinct: bool = True):
 		"""Return `COUNT(*)` for given DocType and filters."""

frappe/query_builder/terms.py

@@ -1,10 +1,11 @@
-from datetime import time, timedelta
+from datetime import datetime, time, timedelta
 from typing import Any
 
 from pypika.queries import QueryBuilder
 from pypika.terms import Criterion, Function, ValueWrapper
 from pypika.utils import format_alias_sql
 
+import frappe
 from frappe.utils.data import format_time, format_timedelta
 
 
@@ -56,6 +57,8 @@ class ParameterizedValueWrapper(ValueWrapper):
 				self.value = format_timedelta(self.value)
 			elif isinstance(self.value, time):
 				self.value = format_time(self.value)
+			elif isinstance(self.value, datetime):
+				self.value = frappe.db.format_datetime(self.value)
 
 			sql = self.get_value_sql(
 				quote_char=quote_char,

frappe/tests/test_db.py

@@ -17,6 +17,7 @@ from frappe.query_builder.functions import Concat_ws
 from frappe.tests.test_query_builder import db_type_is, run_only_if
 from frappe.tests.utils import FrappeTestCase, patch_hooks, timeout
 from frappe.utils import add_days, now, random_string, set_request
+from frappe.utils.data import now_datetime
 from frappe.utils.testutils import clear_custom_fields
 
 
@@ -504,6 +505,19 @@ class TestDB(FrappeTestCase):
 
 		self.assertEqual(frappe.db.exists(dt, [["name", "=", dn]]), dn)
 
+	def test_datetime_serialization(self):
+		dt = now_datetime()
+		dt = dt.replace(microsecond=0)
+		self.assertEqual(str(dt), str(frappe.db.sql("select %s", dt)[0][0]))
+
+		frappe.db.exists("User", {"creation": (">", dt)})
+		self.assertIn(str(dt), str(frappe.db.last_query))
+
+		before = now_datetime()
+		note = frappe.get_doc(doctype="Note", title=frappe.generate_hash(), content="something").insert()
+		after = now_datetime()
+		self.assertEqual(note.name, frappe.db.exists("Note", {"creation": ("between", (before, after))}))
+
 	def test_bulk_insert(self):
 		current_count = frappe.db.count("ToDo")
 		test_body = f"test_bulk_insert - {random_string(10)}"