fix OneToOneField without related_name

django-stubs/db/models/fields/__init__.pyi

@@ -116,6 +116,9 @@ class FloatField(Field[_ST, _GT]):
 class DecimalField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, float, decimal.Decimal, Combinable]
     _pyi_private_get_type: decimal.Decimal
+    # attributes
+    max_digits: int = ...
+    decimal_places: int = ...
     def __init__(
         self,
         verbose_name: Optional[Union[str, bytes]] = ...,

mypy_django_plugin/transformers/models.py

@@ -1,7 +1,8 @@
 from abc import ABCMeta, abstractmethod
 from abc import ABCMeta, abstractmethod
-from typing import cast
+from typing import cast, Type
 
+from django.db.models.base import Model
 from django.db.models.fields.related import ForeignKey
 from django.db.models.fields.reverse_related import ManyToManyRel, ManyToOneRel, OneToOneRel
 from mypy.newsemanal.semanal import NewSemanticAnalyzer
@@ -45,9 +46,15 @@ class ModelClassInitializer(metaclass=ABCMeta):
         var.is_inferred = True
         self.model_classdef.info.names[name] = SymbolTableNode(MDEF, var, plugin_generated=True)
 
-    @abstractmethod
     def run(self) -> None:
-        raise NotImplementedError()
+        model_cls = self.django_context.get_model_class_by_fullname(self.model_classdef.fullname)
+        if model_cls is None:
+            return
+        self.run_with_model_cls(model_cls)
+
+    @abstractmethod
+    def run_with_model_cls(self, model_cls):
+        pass
 
 
 class InjectAnyAsBaseForNestedMeta(ModelClassInitializer):
@@ -63,7 +70,7 @@ class InjectAnyAsBaseForNestedMeta(ModelClassInitializer):
     to get around incompatible Meta inner classes for different models.
     """
 
-    def run(self) -> None:
+    def run_with_model_cls(self, model_cls: Type[Model])-> None:
         meta_node = helpers.get_nested_meta_node_for_current_class(self.model_classdef.info)
         if meta_node is None:
             return None
@@ -71,11 +78,7 @@ class InjectAnyAsBaseForNestedMeta(ModelClassInitializer):
 
 
 class AddDefaultPrimaryKey(ModelClassInitializer):
-    def run(self) -> None:
-        model_cls = self.django_context.get_model_class_by_fullname(self.model_classdef.fullname)
-        if model_cls is None:
-            return
-
+    def run_with_model_cls(self, model_cls: Type[Model])-> None:
         auto_field = model_cls._meta.auto_field
         if auto_field and not self.model_classdef.info.has_readable_member(auto_field.attname):
             # autogenerated field
@@ -88,11 +91,7 @@ class AddDefaultPrimaryKey(ModelClassInitializer):
 
 
 class AddRelatedModelsId(ModelClassInitializer):
-    def run(self) -> None:
-        model_cls = self.django_context.get_model_class_by_fullname(self.model_classdef.fullname)
-        if model_cls is None:
-            return
-
+    def run_with_model_cls(self, model_cls: Type[Model])-> None:
         for field in model_cls._meta.get_fields():
             if isinstance(field, ForeignKey):
                 rel_primary_key_field = self.django_context.get_primary_key_field(field.related_model)
@@ -104,11 +103,7 @@ class AddRelatedModelsId(ModelClassInitializer):
 
 
 class AddManagers(ModelClassInitializer):
-    def run(self):
-        model_cls = self.django_context.get_model_class_by_fullname(self.model_classdef.fullname)
-        if model_cls is None:
-            return
-
+    def run_with_model_cls(self, model_cls: Type[Model])-> None:
         for manager_name, manager in model_cls._meta.managers_map.items():
             if manager_name not in self.model_classdef.info.names:
                 manager_fullname = helpers.get_class_fullname(manager.__class__)
@@ -126,14 +121,17 @@ class AddManagers(ModelClassInitializer):
 
         # add related managers
         for relation in self.django_context.get_model_relations(model_cls):
-            attname = relation.related_name
+            attname = relation.get_accessor_name()
             if attname is None:
-                attname = relation.name + '_set'
+                # no reverse accessor
+                continue
 
             related_model_info = self.lookup_class_typeinfo_or_incomplete_defn_error(relation.related_model)
+
             if isinstance(relation, OneToOneRel):
                 self.add_new_node_to_model_class(attname, Instance(related_model_info, []))
                 continue
+
             if isinstance(relation, (ManyToOneRel, ManyToManyRel)):
                 manager_info = self.lookup_typeinfo_or_incomplete_defn_error(fullnames.RELATED_MANAGER_CLASS_FULLNAME)
                 self.add_new_node_to_model_class(attname,
@@ -142,11 +140,7 @@ class AddManagers(ModelClassInitializer):
 
 
 class AddExtraFieldMethods(ModelClassInitializer):
-    def run(self):
-        model_cls = self.django_context.get_model_class_by_fullname(self.model_classdef.fullname)
-        if model_cls is None:
-            return
-
+    def run_with_model_cls(self, model_cls: Type[Model])-> None:
         # get_FOO_display for choices
         for field in self.django_context.get_model_fields(model_cls):
             if field.choices:
@@ -178,7 +172,7 @@ class AddExtraFieldMethods(ModelClassInitializer):
 
 
 class AddMetaOptionsAttribute(ModelClassInitializer):
-    def run(self):
+    def run_with_model_cls(self, model_cls: Type[Model])-> None:
         if '_meta' not in self.model_classdef.info.names:
             options_info = self.lookup_typeinfo_or_incomplete_defn_error(fullnames.OPTIONS_CLASS_FULLNAME)
             self.add_new_node_to_model_class('_meta',

test-data/typecheck/fields/test_related.yml

@@ -84,6 +84,23 @@
                 class Book(models.Model):
                     publisher = models.ForeignKey(to='myapp.Publisher', on_delete=models.CASCADE)
 
+-   case: one_to_one_field_no_related_name
+    main: |
+        from myapp.models import User, Profile
+        reveal_type(User().profile)  # N: Revealed type is 'myapp.models.Profile'
+        reveal_type(Profile().user)  # N: Revealed type is 'myapp.models.User*'
+    installed_apps:
+        - myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from django.db import models
+                class User(models.Model):
+                    pass
+                class Profile(models.Model):
+                    user = models.OneToOneField(to=User, on_delete=models)
+
 -   case: test_circular_dependency_in_imports_with_foreign_key
     main: |
         from myapp import models