fixed in general

ormar/relations/relation.py

@@ -49,7 +49,10 @@ class Relation:
             if i not in self._to_remove
         ]
         self.related_models = RelationProxy(
-            relation=self, type_=self._type,  field_name=self.field_name, data_=cleaned_data
+            relation=self,
+            type_=self._type,
+            field_name=self.field_name,
+            data_=cleaned_data,
         )
         relation_name = self._owner.resolve_relation_name(self._owner, self.to)
         self._owner.__dict__[relation_name] = cleaned_data

ormar/relations/relation_manager.py

@@ -65,17 +65,17 @@ class RelationsManager:
         relation_name: str,
     ) -> None:
         to_field: Type[BaseField] = child.Meta.model_fields[relation_name]
-        print('comming', child_name, relation_name)
+        # print('comming', child_name, relation_name)
         (parent, child, child_name, to_name,) = get_relations_sides_and_names(
             to_field, parent, child, child_name, virtual
         )
 
-        print('adding', parent.get_name(), child.get_name(), child_name)
+        # print('adding', parent.get_name(), child.get_name(), child_name)
         parent_relation = parent._orm._get(child_name)
         if parent_relation:
             parent_relation.add(child)  # type: ignore
 
-        print('adding', child.get_name(), parent.get_name(), child_name)
+        # print('adding', child.get_name(), parent.get_name(), child_name)
         child_relation = child._orm._get(to_name)
         if child_relation:
             child_relation.add(parent)

ormar/relations/relation_proxy.py

@@ -1,4 +1,4 @@
-from typing import Any, TYPE_CHECKING
+from typing import Any, Optional, TYPE_CHECKING
 
 import ormar
 from ormar.exceptions import NoMatch, RelationshipInstanceError
@@ -12,7 +12,11 @@ if TYPE_CHECKING:  # pragma no cover
 
 class RelationProxy(list):
     def __init__(
-        self, relation: "Relation", type_: "RelationType",  field_name: str, data_: Any = None
+        self,
+        relation: "Relation",
+        type_: "RelationType",
+        field_name: str,
+        data_: Any = None,
     ) -> None:
         super().__init__(data_ or ())
         self.relation: "Relation" = relation
@@ -20,8 +24,17 @@ class RelationProxy(list):
         self.field_name = field_name
         self._owner: "Model" = self.relation.manager.owner
         self.queryset_proxy = QuerysetProxy(relation=self.relation, type_=type_)
+        self._related_field_name: Optional[str] = None
+
+    @property
+    def related_field_name(self) -> str:
+        if self._related_field_name:
+            return self._related_field_name
         owner_field = self._owner.Meta.model_fields[self.field_name]
-        self.related_field_name = owner_field.related_name or self._owner.get_name() + 's'
+        self._related_field_name = (
+            owner_field.related_name or self._owner.get_name() + "s"
+        )
+        return self._related_field_name
 
     def __getattribute__(self, item: str) -> Any:
         if item in ["count", "clear"]: