Fix for mongo 6.

Author: WaVEV

django_mongodb_backend/expressions/builtins.py

@@ -29,6 +29,7 @@
 
 
 # EXTRA IS TOTALLY IGNORED
+# shall check if we could optimize match here
 def case(self, compiler, connection, **extra):  # noqa: ARG001
     case_parts = []
     for case in self.cases:

django_mongodb_backend/functions.py

@@ -157,15 +157,18 @@ def wrapped(self, compiler, connection, as_path=False):
             lhs_mql = process_lhs(self, compiler, connection, as_path=True)
             return lhs_mql.upper()
         lhs_mql = process_lhs(self, compiler, connection, as_path=False)
-        return {
-            "$expr": {
-                "$cond": {
-                    "if": connection.mongo_operators_expr["isnull"](lhs_mql, True),
-                    "then": None,
-                    "else": {f"${operator}": lhs_mql},
-                }
+        inner_expression = {
+            "$cond": {
+                "if": connection.mongo_operators_expr["isnull"](lhs_mql, True),
+                "then": None,
+                "else": {f"${operator}": lhs_mql},
             }
         }
+        # we need to wrap this, because it will be handled in a no expression tree.
+        # needed in MongoDB 6.
+        if as_path:
+            return {"$expr": inner_expression}
+        return inner_expression
 
     return wrapped
 

django_mongodb_backend/lookups.py

@@ -48,7 +48,9 @@ def builtin_lookup(self, compiler, connection, as_path=False):
 
     value = process_rhs(self, compiler, connection)
     lhs_mql = process_lhs(self, compiler, connection, as_path=False)
-    return {"$expr": connection.mongo_operators_expr[self.lookup_name](lhs_mql, value)}
+    if as_path:
+        return {"$expr": connection.mongo_operators_expr[self.lookup_name](lhs_mql, value)}
+    return connection.mongo_operators_expr[self.lookup_name](lhs_mql, value)
 
 
 _field_resolve_expression_parameter = FieldGetDbPrepValueIterableMixin.resolve_expression_parameter
@@ -116,7 +118,9 @@ def is_null(self, compiler, connection, as_path=False):
         lhs_mql = process_lhs(self, compiler, connection, as_path=as_path)
         return connection.mongo_operators_match["isnull"](lhs_mql, self.rhs)
     lhs_mql = process_lhs(self, compiler, connection, as_path=False)
-    return {"$expr": connection.mongo_operators_expr["isnull"](lhs_mql, self.rhs)}
+    if as_path:
+        return {"$expr": connection.mongo_operators_expr["isnull"](lhs_mql, self.rhs)}
+    return connection.mongo_operators_expr["isnull"](lhs_mql, self.rhs)
 
 
 # from https://www.pcre.org/current/doc/html/pcre2pattern.html#SEC4