fix: Ported subqry to branch for compatibility

Via https://github.com/frappe/frappe/pull/16107

frappe/query_builder/terms.py

@@ -1,10 +1,12 @@
 from datetime import timedelta
 from typing import Any, Dict, Optional
-from frappe.utils.data import format_timedelta
 
-from pypika.terms import Function, ValueWrapper
+from pypika.queries import QueryBuilder
+from pypika.terms import Criterion, Function, ValueWrapper
 from pypika.utils import format_alias_sql
 
+from frappe.utils.data import format_timedelta
+
 
 class NamedParameterWrapper:
 	"""Utility class to hold parameter values and keys"""
@@ -100,3 +102,12 @@ class ParameterizedFunction(Function):
 			)
 
 		return function_sql
+
+class subqry(Criterion):
+	def __init__(self, subq: QueryBuilder, alias: Optional[str] = None,) -> None:
+		super().__init__(alias)
+		self.subq = subq
+
+	def get_sql(self, **kwg: Any) -> str:
+		kwg["subquery"] = True
+		return self.subq.get_sql(**kwg)

frappe/utils/nestedset.py

@@ -295,6 +295,8 @@ class NestedSet(Document):
 def get_root_of(doctype):
 	"""Get root element of a DocType with a tree structure"""
 	from frappe.query_builder.functions import Count
+	from frappe.query_builder.terms import subqry
+
 	Table = DocType(doctype)
 	t1 = Table.as_("t1")
 	t2 = Table.as_("t2")
@@ -303,7 +305,7 @@ def get_root_of(doctype):
 		(t2.lft < t1.lft) & (t2.rgt > t1.rgt)
 	)
 	result = frappe.qb.from_(t1).select(t1.name).where(
-		(subq == 0) & (t1.rgt > t1.lft) # depends on https://github.com/frappe/frappe/pull/16107
+		(subqry(subq) == 0) & (t1.rgt > t1.lft)
 	).run()
 
 	return result[0][0] if result else None