feat(wip): Custom filters in db.query engine

* Added provision for semi-implemneted version
    * Hard to fix it completely given it's broken on develop / desk
* Added TODO for adding nestedset related filters

frappe/database/query.py

@@ -1,9 +1,11 @@
 import operator
 import re
+from functools import cached_property
 from typing import Any, Dict, List, Tuple, Union
 
 import frappe
 from frappe import _
+from frappe.boot import get_additional_filters_from_hooks
 from frappe.model.db_query import get_timespan_date_range
 from frappe.query_builder import Criterion, Field, Order, Table
 
@@ -138,6 +140,7 @@ def change_orderby(order: str):
 	return order[0], Order.desc
 
 
+# default operators
 OPERATOR_MAP: Dict[str, "function"] = {
 	"+": operator.add,
 	"=": operator.eq,
@@ -157,12 +160,35 @@ OPERATOR_MAP: Dict[str, "function"] = {
 	"between": func_between,
 	"is": func_is,
 	"timespan": func_timespan,
+	# TODO: Add support for nested set
+	# TODO: Add support for custom operators (WIP) - via filters_config hooks
 }
 
 
 class Query:
 	tables: dict = {}
 
+	@cached_property
+	def OPERATOR_MAP(self):
+		# default operators
+		all_operators = OPERATOR_MAP.copy()
+
+		# update with site-specific custom operators
+		additional_filters_config = get_additional_filters_from_hooks()
+
+		if additional_filters_config:
+			from frappe.utils.commands import warn
+
+			warn("'filters_config' hook is not completely implemented yet in frappe.db.query engine")
+
+		for operator, function in additional_filters_config.items():
+			if callable(function):
+				all_operators.update({operator.casefold(): function})
+			elif isinstance(function, dict):
+				all_operators[operator.casefold()] = frappe.get_attr(function.get("get_field"))()["operator"]
+
+		return all_operators
+
 	def get_condition(self, table: Union[str, Table], **kwargs) -> frappe.qb:
 		"""Get initial table object
 
@@ -243,14 +269,14 @@ class Query:
 		if isinstance(filters, list):
 			for f in filters:
 				if not isinstance(f, (list, tuple)):
-					_operator = OPERATOR_MAP[filters[1].casefold()]
+					_operator = self.OPERATOR_MAP[filters[1].casefold()]
 					if not isinstance(filters[0], str):
 						conditions = make_function(filters[0], filters[2])
 						break
 					conditions = conditions.where(_operator(Field(filters[0]), filters[2]))
 					break
 				else:
-					_operator = OPERATOR_MAP[f[-2].casefold()]
+					_operator = self.OPERATOR_MAP[f[-2].casefold()]
 					if len(f) == 4:
 						table_object = self.get_table(f[0])
 						_field = table_object[f[1]]
@@ -279,13 +305,13 @@ class Query:
 
 		for key in filters:
 			value = filters.get(key)
-			_operator = OPERATOR_MAP["="]
+			_operator = self.OPERATOR_MAP["="]
 
 			if not isinstance(key, str):
 				conditions = conditions.where(make_function(key, value))
 				continue
 			if isinstance(value, (list, tuple)):
-				_operator = OPERATOR_MAP[value[0].casefold()]
+				_operator = self.OPERATOR_MAP[value[0].casefold()]
 				conditions = conditions.where(_operator(Field(key), value[1]))
 			else:
 				if value is not None:

frappe/utils/commands.py

@@ -59,7 +59,7 @@ def log(message, colour=""):
 	print(colour + message + end_line)
 
 
-def warn(message, category=None):
+def warn(message, category=None, stacklevel=2):
 	from warnings import warn
 
-	warn(message=message, category=category, stacklevel=2)
+	warn(message=message, category=category, stacklevel=stacklevel)