Add as_mql method to OrderBy

Author: WaVEV

django_mongodb/compiler.py

@@ -469,10 +469,10 @@ def _get_ordering(self):
         idx = itertools.count(start=1)
         for order in self.order_by_objs or []:
             if isinstance(order.expression, Col):
-                field_name = order.expression.as_mql(self, self.connection).removeprefix("$")
+                field_name = order.as_mql(self, self.connection).removeprefix("$")
                 fields.append((order.expression.target.column, order.expression))
             elif isinstance(order.expression, Ref):
-                field_name = order.expression.as_mql(self, self.connection).removeprefix("$")
+                field_name = order.as_mql(self, self.connection).removeprefix("$")
             else:
                 field_name = f"__order{next(idx)}"
                 fields.append((field_name, order.expression))

django_mongodb/query.py

@@ -3,7 +3,7 @@
 
 from django.core.exceptions import EmptyResultSet, FullResultSet
 from django.db import DatabaseError, IntegrityError
-from django.db.models.expressions import Case, When
+from django.db.models.expressions import Case, OrderBy, When
 from django.db.models.functions import Mod
 from django.db.models.lookups import Exact
 from django.db.models.sql.constants import INNER
@@ -166,6 +166,10 @@ def join(self, compiler, connection):
     return lookup_pipeline
 
 
+def order_by(self, compiler, connection):
+    return self.expression.as_mql(compiler, connection)
+
+
 def where_node(self, compiler, connection):
     if self.connector == AND:
         full_needed, empty_needed = len(self.children), 1
@@ -231,4 +235,5 @@ def where_node(self, compiler, connection):
 def register_nodes():
     Join.as_mql = join
     NothingNode.as_mql = NothingNode.as_sql
+    OrderBy.as_mql = order_by
     WhereNode.as_mql = where_node