preliminary support for strict_optional

2025-12-07 04:34:29 +08:00 · 2019-02-17 18:07:53 +03:00
parent 6763217a80
commit e9f9202ed1
23 changed files with 614 additions and 343 deletions
--- a/django-stubs/contrib/admin/models.pyi
+++ b/django-stubs/contrib/admin/models.pyi
@@ -25,7 +25,7 @@ class LogEntryManager(models.Manager["LogEntry"]):
 class LogEntry(models.Model):
    action_time: models.DateTimeField = ...
    user: models.ForeignKey = ...
-    content_type: models.ForeignKey[ContentType] = ...
+    content_type: models.ForeignKey = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id: models.TextField = ...
    object_repr: models.CharField = ...
    action_flag: models.PositiveSmallIntegerField = ...
--- a/django-stubs/contrib/auth/models.pyi
+++ b/django-stubs/contrib/auth/models.pyi
@@ -15,7 +15,7 @@ class PermissionManager(models.Manager):
 class Permission(models.Model):
    content_type_id: int
    name: models.CharField = ...
-    content_type: models.ForeignKey[ContentType] = ...
+    content_type: models.ForeignKey = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    codename: models.CharField = ...
    def natural_key(self) -> Tuple[str, str, str]: ...

@@ -24,7 +24,7 @@ class GroupManager(models.Manager):

 class Group(models.Model):
    name: models.CharField = ...
-    permissions: models.ManyToManyField[Permission] = ...
+    permissions: models.ManyToManyField = models.ManyToManyField(Permission)
    def natural_key(self): ...

 class UserManager(BaseUserManager):
@@ -37,8 +37,8 @@ class UserManager(BaseUserManager):

 class PermissionsMixin(models.Model):
    is_superuser: models.BooleanField = ...
-    groups: models.ManyToManyField[Group] = ...
-    user_permissions: models.ManyToManyField[Permission] = ...
+    groups: models.ManyToManyField = models.ManyToManyField(Group)
+    user_permissions: models.ManyToManyField = models.ManyToManyField(Permission)
    def get_group_permissions(self, obj: None = ...) -> Set[str]: ...
    def get_all_permissions(self, obj: Optional[str] = ...) -> Set[str]: ...
    def has_perm(self, perm: Union[Tuple[str, Any], str], obj: Optional[str] = ...) -> bool: ...
--- a/django-stubs/contrib/contenttypes/fields.pyi
+++ b/django-stubs/contrib/contenttypes/fields.pyi
@@ -1,4 +1,4 @@
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union, Generic

 from django.contrib.contenttypes.models import ContentType
 from django.core.checks.messages import Error
--- a/django-stubs/contrib/postgres/fields/array.pyi
+++ b/django-stubs/contrib/postgres/fields/array.pyi
@@ -1,20 +1,51 @@
-from typing import Any, Generic, List, Optional, Sequence, TypeVar
+from typing import Any, Iterable, List, Optional, Sequence, TypeVar, Union
+
+from django.db.models.expressions import Combinable
+from django.db.models.fields import Field, _ErrorMessagesToOverride, _FieldChoices, _ValidatorCallable

-from django.db.models.fields import Field
 from .mixins import CheckFieldDefaultMixin

-_T = TypeVar("_T", bound=Field)
+# __set__ value type
+_ST = TypeVar("_ST")
+# __get__ return type
+_GT = TypeVar("_GT")
+
+class ArrayField(CheckFieldDefaultMixin, Field[_ST, _GT]):
+    _pyi_private_set_type: Union[Sequence[Any], Combinable]
+    _pyi_private_get_type: List[Any]

-class ArrayField(CheckFieldDefaultMixin, Field, Generic[_T]):
    empty_strings_allowed: bool = ...
    default_error_messages: Any = ...
    base_field: Any = ...
    size: Any = ...
    default_validators: Any = ...
    from_db_value: Any = ...
-    def __init__(self, base_field: _T, size: Optional[int] = ..., **kwargs: Any) -> None: ...
+    def __init__(
+        self,
+        base_field: Field,
+        size: Optional[int] = ...,
+        verbose_name: Optional[Union[str, bytes]] = ...,
+        name: Optional[str] = ...,
+        primary_key: bool = ...,
+        max_length: Optional[int] = ...,
+        unique: bool = ...,
+        blank: bool = ...,
+        null: bool = ...,
+        db_index: bool = ...,
+        default: Any = ...,
+        editable: bool = ...,
+        auto_created: bool = ...,
+        serialize: bool = ...,
+        unique_for_date: Optional[str] = ...,
+        unique_for_month: Optional[str] = ...,
+        unique_for_year: Optional[str] = ...,
+        choices: Optional[_FieldChoices] = ...,
+        help_text: str = ...,
+        db_column: Optional[str] = ...,
+        db_tablespace: Optional[str] = ...,
+        validators: Iterable[_ValidatorCallable] = ...,
+        error_messages: Optional[_ErrorMessagesToOverride] = ...,
+    ) -> None: ...
    @property
    def description(self): ...
    def get_transform(self, name: Any): ...
-    def __set__(self, instance, value: Sequence[_T]) -> None: ...
-    def __get__(self, instance, owner) -> List[_T]: ...
--- a/django-stubs/db/models/fields/init.pyi
+++ b/django-stubs/db/models/fields/init.pyi
@@ -1,16 +1,15 @@
-import uuid
-from datetime import date, time, datetime, timedelta
-from typing import Any, Optional, Tuple, Iterable, Callable, Dict, Union, Type, TypeVar, Generic
 import decimal
-
-from typing_extensions import Literal
+import uuid
+from datetime import date, datetime, time, timedelta
+from typing import Any, Callable, Dict, Generic, Iterable, Optional, Tuple, Type, TypeVar, Union

 from django.db.models import Model
-from django.db.models.query_utils import RegisterLookupMixin
-
-from django.db.models.expressions import F, Combinable
 from django.core.exceptions import FieldDoesNotExist as FieldDoesNotExist
-from django.forms import Widget, Field as FormField
+from django.db.models.expressions import Combinable
+from django.db.models.query_utils import RegisterLookupMixin
+from django.forms import Field as FormField, Widget
+from typing_extensions import Literal
+
 from .mixins import NOT_PROVIDED as NOT_PROVIDED

 _Choice = Tuple[Any, Any]
@@ -20,7 +19,15 @@ _FieldChoices = Iterable[Union[_Choice, _ChoiceNamedGroup]]
 _ValidatorCallable = Callable[..., None]
 _ErrorMessagesToOverride = Dict[str, Any]

-class Field(RegisterLookupMixin):
+# __set__ value type
+_ST = TypeVar("_ST")
+# __get__ return type
+_GT = TypeVar("_GT")
+
+class Field(RegisterLookupMixin, Generic[_ST, _GT]):
+    _pyi_private_set_type: Any
+    _pyi_private_get_type: Any
+
    widget: Widget
    help_text: str
    db_table: str
@@ -52,7 +59,8 @@ class Field(RegisterLookupMixin):
        validators: Iterable[_ValidatorCallable] = ...,
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...
-    def __get__(self, instance, owner) -> Any: ...
+    def __set__(self, instance, value: _ST) -> None: ...
+    def __get__(self, instance, owner) -> _GT: ...
    def deconstruct(self) -> Any: ...
    def set_attributes_from_name(self, name: str) -> None: ...
    def db_type(self, connection: Any) -> str: ...
@@ -63,23 +71,25 @@ class Field(RegisterLookupMixin):
    def contribute_to_class(self, cls: Type[Model], name: str, private_only: bool = ...) -> None: ...
    def to_python(self, value: Any) -> Any: ...

-class IntegerField(Field):
-    def __set__(self, instance, value: Union[int, Combinable, Literal[""]]) -> None: ...
-    def __get__(self, instance, owner) -> int: ...
+class IntegerField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[int, Combinable, Literal[""]]
+    _pyi_private_get_type: int

 class PositiveIntegerRelDbTypeMixin:
    def rel_db_type(self, connection: Any): ...

-class PositiveIntegerField(PositiveIntegerRelDbTypeMixin, IntegerField): ...
-class PositiveSmallIntegerField(PositiveIntegerRelDbTypeMixin, IntegerField): ...
-class SmallIntegerField(IntegerField): ...
-class BigIntegerField(IntegerField): ...
+class PositiveIntegerField(PositiveIntegerRelDbTypeMixin, IntegerField[_ST, _GT]): ...
+class PositiveSmallIntegerField(PositiveIntegerRelDbTypeMixin, IntegerField[_ST, _GT]): ...
+class SmallIntegerField(IntegerField[_ST, _GT]): ...
+class BigIntegerField(IntegerField[_ST, _GT]): ...

-class FloatField(Field):
-    def __set__(self, instance, value: Union[float, int, str, Combinable]) -> float: ...
-    def __get__(self, instance, owner) -> float: ...
+class FloatField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[float, int, str, Combinable]
+    _pyi_private_get_type: float

-class DecimalField(Field):
+class DecimalField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, float, decimal.Decimal, Combinable]
+    _pyi_private_get_type: decimal.Decimal
    def __init__(
        self,
        verbose_name: Optional[Union[str, bytes]] = ...,
@@ -102,13 +112,14 @@ class DecimalField(Field):
        validators: Iterable[_ValidatorCallable] = ...,
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...
-    def __set__(self, instance, value: Union[str, float, decimal.Decimal, Combinable]) -> decimal.Decimal: ...
-    def __get__(self, instance, owner) -> decimal.Decimal: ...

-class AutoField(Field):
-    def __get__(self, instance, owner) -> int: ...
+class AutoField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[Combinable, int, str]
+    _pyi_private_get_type: int

-class CharField(Field):
+class CharField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, int, Combinable]
+    _pyi_private_get_type: str
    def __init__(
        self,
        verbose_name: Optional[Union[str, bytes]] = ...,
@@ -133,10 +144,8 @@ class CharField(Field):
        validators: Iterable[_ValidatorCallable] = ...,
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...
-    def __set__(self, instance, value: Union[str, int, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> str: ...

-class SlugField(CharField):
+class SlugField(CharField[_ST, _GT]):
    def __init__(
        self,
        verbose_name: Optional[Union[str, bytes]] = ...,
@@ -163,25 +172,29 @@ class SlugField(CharField):
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...

-class EmailField(CharField): ...
-class URLField(CharField): ...
+class EmailField(CharField[_ST, _GT]): ...
+class URLField(CharField[_ST, _GT]): ...

-class TextField(Field):
-    def __set__(self, instance, value: Union[str, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> str: ...
+class TextField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, Combinable]
+    _pyi_private_get_type: str

-class BooleanField(Field):
-    def __set__(self, instance, value: Union[bool, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> bool: ...
+class BooleanField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[bool, Combinable]
+    _pyi_private_get_type: bool

-class NullBooleanField(Field):
-    def __set__(self, instance, value: Optional[Union[bool, Combinable]]) -> None: ...
-    def __get__(self, instance, owner) -> Optional[bool]: ...
+class NullBooleanField(Field[_ST, _GT]):
+    _pyi_private_set_type: Optional[Union[bool, Combinable]]
+    _pyi_private_get_type: Optional[bool]

-class IPAddressField(Field):
-    def __get__(self, instance, owner) -> str: ...
+class IPAddressField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, Combinable]
+    _pyi_private_get_type: str
+
+class GenericIPAddressField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, int, Callable[..., Any], Combinable]
+    _pyi_private_get_type: str

-class GenericIPAddressField(Field):
    default_error_messages: Any = ...
    unpack_ipv4: Any = ...
    protocol: Any = ...
@@ -207,12 +220,12 @@ class GenericIPAddressField(Field):
        validators: Iterable[_ValidatorCallable] = ...,
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ) -> None: ...
-    def __set__(self, instance, value: Union[str, int, Callable[..., Any], Combinable]): ...
-    def __get__(self, instance, owner) -> str: ...

 class DateTimeCheckMixin: ...

-class DateField(DateTimeCheckMixin, Field):
+class DateField(DateTimeCheckMixin, Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, date, datetime, Combinable]
+    _pyi_private_get_type: date
    def __init__(
        self,
        verbose_name: Optional[Union[str, bytes]] = ...,
@@ -236,10 +249,10 @@ class DateField(DateTimeCheckMixin, Field):
        validators: Iterable[_ValidatorCallable] = ...,
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...
-    def __set__(self, instance, value: Union[str, date, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> date: ...

-class TimeField(DateTimeCheckMixin, Field):
+class TimeField(DateTimeCheckMixin, Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, time, datetime, Combinable]
+    _pyi_private_get_type: time
    def __init__(
        self,
        verbose_name: Optional[Union[str, bytes]] = ...,
@@ -262,18 +275,15 @@ class TimeField(DateTimeCheckMixin, Field):
        validators: Iterable[_ValidatorCallable] = ...,
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...
-    def __set__(self, instance, value: Union[str, time, datetime, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> time: ...

-class DateTimeField(DateField):
-    def __set__(self, instance, value: Union[str, date, datetime, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> datetime: ...
+class DateTimeField(DateField[_ST, _GT]):
+    _pyi_private_get_type: datetime

-class UUIDField(Field):
-    def __set__(self, instance, value: Union[str, uuid.UUID]) -> None: ...
-    def __get__(self, instance, owner) -> uuid.UUID: ...
+class UUIDField(Field[_ST, _GT]):
+    _pyi_private_set_type: Union[str, uuid.UUID]
+    _pyi_private_get_type: uuid.UUID

-class FilePathField(Field):
+class FilePathField(Field[_ST, _GT]):
    path: str = ...
    match: Optional[Any] = ...
    recursive: bool = ...
@@ -306,10 +316,10 @@ class FilePathField(Field):
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...

-class BinaryField(Field): ...
+class BinaryField(Field[_ST, _GT]): ...

-class DurationField(Field):
-    def __get__(self, instance, owner) -> timedelta: ...
+class DurationField(Field[_ST, _GT]):
+    _pyi_private_get_type: timedelta

-class BigAutoField(AutoField): ...
-class CommaSeparatedIntegerField(CharField): ...
+class BigAutoField(AutoField[_ST, _GT]): ...
+class CommaSeparatedIntegerField(CharField[_ST, _GT]): ...
--- a/django-stubs/db/models/fields/related.pyi
+++ b/django-stubs/db/models/fields/related.pyi
@@ -49,7 +49,12 @@ _ErrorMessagesToOverride = Dict[str, Any]

 RECURSIVE_RELATIONSHIP_CONSTANT: str = ...

-class RelatedField(FieldCacheMixin, Field):
+# __set__ value type
+_ST = TypeVar("_ST")
+# __get__ return type
+_GT = TypeVar("_GT")
+
+class RelatedField(FieldCacheMixin, Field[_ST, _GT]):
    one_to_many: bool = ...
    one_to_one: bool = ...
    many_to_many: bool = ...
@@ -83,6 +88,7 @@ class ForeignObject(RelatedField):
        related_query_name: None = ...,
        limit_choices_to: Optional[Union[Dict[str, Any], Callable[[], Any]]] = ...,
        parent_link: bool = ...,
+        db_constraint: bool = ...,
        swappable: bool = ...,
        verbose_name: Optional[str] = ...,
        name: Optional[str] = ...,
@@ -103,17 +109,82 @@ class ForeignObject(RelatedField):
        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ): ...

-class ForeignKey(RelatedField, Generic[_T]):
-    def __init__(self, to: Union[Type[_T], str], on_delete: Any, related_name: str = ..., **kwargs): ...
-    def __set__(self, instance, value: Union[Model, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> _T: ...
+class ForeignKey(RelatedField[_ST, _GT]):
+    _pyi_private_set_type: Union[Any, Combinable]
+    _pyi_private_get_type: Any
+    def __init__(
+        self,
+        to: Union[Type[Model], str],
+        on_delete: Callable[..., None],
+        to_field: Optional[str] = ...,
+        related_name: str = ...,
+        related_query_name: Optional[str] = ...,
+        limit_choices_to: Optional[Union[Dict[str, Any], Callable[[], Any], Q]] = ...,
+        parent_link: bool = ...,
+        db_constraint: bool = ...,
+        verbose_name: Optional[Union[str, bytes]] = ...,
+        name: Optional[str] = ...,
+        primary_key: bool = ...,
+        max_length: Optional[int] = ...,
+        unique: bool = ...,
+        blank: bool = ...,
+        null: bool = ...,
+        db_index: bool = ...,
+        default: Any = ...,
+        editable: bool = ...,
+        auto_created: bool = ...,
+        serialize: bool = ...,
+        unique_for_date: Optional[str] = ...,
+        unique_for_month: Optional[str] = ...,
+        unique_for_year: Optional[str] = ...,
+        choices: Optional[_FieldChoices] = ...,
+        help_text: str = ...,
+        db_column: Optional[str] = ...,
+        db_tablespace: Optional[str] = ...,
+        validators: Iterable[_ValidatorCallable] = ...,
+        error_messages: Optional[_ErrorMessagesToOverride] = ...,
+    ): ...

-class OneToOneField(RelatedField, Generic[_T]):
-    def __init__(self, to: Union[Type[_T], str], on_delete: Any, related_name: str = ..., **kwargs): ...
-    def __set__(self, instance, value: Union[Model, Combinable]) -> None: ...
-    def __get__(self, instance, owner) -> _T: ...
+class OneToOneField(RelatedField[_ST, _GT]):
+    _pyi_private_set_type: Union[Any, Combinable]
+    _pyi_private_get_type: Any
+    def __init__(
+        self,
+        to: Union[Type[Model], str],
+        on_delete: Any,
+        to_field: Optional[str] = ...,
+        related_name: str = ...,
+        related_query_name: Optional[str] = ...,
+        limit_choices_to: Optional[Union[Dict[str, Any], Callable[[], Any], Q]] = ...,
+        parent_link: bool = ...,
+        db_constraint: bool = ...,
+        verbose_name: Optional[Union[str, bytes]] = ...,
+        name: Optional[str] = ...,
+        primary_key: bool = ...,
+        max_length: Optional[int] = ...,
+        unique: bool = ...,
+        blank: bool = ...,
+        null: bool = ...,
+        db_index: bool = ...,
+        default: Any = ...,
+        editable: bool = ...,
+        auto_created: bool = ...,
+        serialize: bool = ...,
+        unique_for_date: Optional[str] = ...,
+        unique_for_month: Optional[str] = ...,
+        unique_for_year: Optional[str] = ...,
+        choices: Optional[_FieldChoices] = ...,
+        help_text: str = ...,
+        db_column: Optional[str] = ...,
+        db_tablespace: Optional[str] = ...,
+        validators: Iterable[_ValidatorCallable] = ...,
+        error_messages: Optional[_ErrorMessagesToOverride] = ...,
+    ): ...
+
+class ManyToManyField(RelatedField[_ST, _GT]):
+    _pyi_private_set_type: Sequence[Any]
+    _pyi_private_get_type: RelatedManager[Any]

-class ManyToManyField(RelatedField, Generic[_T]):
    many_to_many: bool = ...
    many_to_one: bool = ...
    one_to_many: bool = ...
@@ -127,17 +198,35 @@ class ManyToManyField(RelatedField, Generic[_T]):
        to: Union[Type[_T], str],
        related_name: Optional[str] = ...,
        related_query_name: Optional[str] = ...,
-        limit_choices_to: Optional[Union[Dict[str, Any], Callable[[], Any]]] = ...,
+        limit_choices_to: Optional[Union[Dict[str, Any], Callable[[], Any], Q]] = ...,
        symmetrical: Optional[bool] = ...,
        through: Optional[Union[str, Type[Model]]] = ...,
        through_fields: Optional[Tuple[str, str]] = ...,
        db_constraint: bool = ...,
        db_table: Optional[str] = ...,
        swappable: bool = ...,
-        **kwargs: Any
+        verbose_name: Optional[Union[str, bytes]] = ...,
+        name: Optional[str] = ...,
+        primary_key: bool = ...,
+        max_length: Optional[int] = ...,
+        unique: bool = ...,
+        blank: bool = ...,
+        null: bool = ...,
+        db_index: bool = ...,
+        default: Any = ...,
+        editable: bool = ...,
+        auto_created: bool = ...,
+        serialize: bool = ...,
+        unique_for_date: Optional[str] = ...,
+        unique_for_month: Optional[str] = ...,
+        unique_for_year: Optional[str] = ...,
+        choices: Optional[_FieldChoices] = ...,
+        help_text: str = ...,
+        db_column: Optional[str] = ...,
+        db_tablespace: Optional[str] = ...,
+        validators: Iterable[_ValidatorCallable] = ...,
+        error_messages: Optional[_ErrorMessagesToOverride] = ...,
    ) -> None: ...
-    def __set__(self, instance, value: Sequence[_T]) -> None: ...
-    def __get__(self, instance, owner) -> RelatedManager[_T]: ...
    def check(self, **kwargs: Any) -> List[Any]: ...
    def deconstruct(self) -> Tuple[Optional[str], str, List[Any], Dict[str, str]]: ...
    def get_path_info(self, filtered_relation: None = ...) -> List[PathInfo]: ...
--- a/mypy_django_plugin/helpers.py
+++ b/mypy_django_plugin/helpers.py
@@ -5,10 +5,12 @@ from mypy.checker import TypeChecker
 from mypy.nodes import AssignmentStmt, ClassDef, Expression, FuncDef, ImportedName, Lvalue, MypyFile, NameExpr, SymbolNode, \
    TypeInfo
 from mypy.plugin import FunctionContext
-from mypy.types import AnyType, CallableType, Instance, Type, TypeOfAny, TypeVarType, UnionType
+from mypy.types import AnyType, CallableType, Instance, NoneTyp, Type, TypeOfAny, TypeVarType, UnionType

 MODEL_CLASS_FULLNAME = 'django.db.models.base.Model'
 FIELD_FULLNAME = 'django.db.models.fields.Field'
+ARRAY_FIELD_FULLNAME = 'django.contrib.postgres.fields.array.ArrayField'
+AUTO_FIELD_FULLNAME = 'django.db.models.fields.AutoField'
 GENERIC_FOREIGN_KEY_FULLNAME = 'django.contrib.contenttypes.fields.GenericForeignKey'
 FOREIGN_KEY_FULLNAME = 'django.db.models.fields.related.ForeignKey'
 ONETOONE_FIELD_FULLNAME = 'django.db.models.fields.related.OneToOneField'
@@ -95,12 +97,13 @@ def parse_bool(expr: Expression) -> Optional[bool]:
    return None


-def reparametrize_with(instance: Instance, new_typevars: typing.List[Type]):
-    return Instance(instance.type, args=new_typevars)
+def reparametrize_instance(instance: Instance, new_args: typing.List[Type]) -> Instance:
+    return Instance(instance.type, args=new_args,
+                    line=instance.line, column=instance.column)


-def fill_typevars_with_any(instance: Instance) -> Type:
-    return reparametrize_with(instance, [AnyType(TypeOfAny.unannotated)])
+def fill_typevars_with_any(instance: Instance) -> Instance:
+    return reparametrize_instance(instance, [AnyType(TypeOfAny.unannotated)])


 def extract_typevar_value(tp: Instance, typevar_name: str) -> Type:
@@ -117,7 +120,7 @@ def fill_typevars(tp: Instance, type_to_fill: Instance) -> Instance:
    for typevar_arg in type_to_fill.args:
        if isinstance(typevar_arg, TypeVarType):
            typevar_values.append(extract_typevar_value(tp, typevar_arg.name))
-    return reparametrize_with(type_to_fill, typevar_values)
+    return Instance(type_to_fill.type, typevar_values)


 def get_argument_by_name(ctx: FunctionContext, name: str) -> Optional[Expression]:
@@ -189,28 +192,12 @@ def iter_over_assignments(


 def extract_field_setter_type(tp: Instance) -> Optional[Type]:
-    if not isinstance(tp, Instance):
-        return None
+    """ Extract __set__ value of a field. """
    if tp.type.has_base(FIELD_FULLNAME):
-        set_method = tp.type.get_method('__set__')
-        if isinstance(set_method, FuncDef) and isinstance(set_method.type, CallableType):
-            if 'value' in set_method.type.arg_names:
-                set_value_type = set_method.type.arg_types[set_method.type.arg_names.index('value')]
-                if isinstance(set_value_type, Instance):
-                    set_value_type = fill_typevars(tp, set_value_type)
-                    return set_value_type
-                elif isinstance(set_value_type, UnionType):
-                    items_no_typevars = []
-                    for item in set_value_type.items:
-                        if isinstance(item, Instance):
-                            item = fill_typevars(tp, item)
-                        items_no_typevars.append(item)
-                    return UnionType(items_no_typevars)
-
-    field_getter_type = extract_field_getter_type(tp)
-    if field_getter_type:
-        return field_getter_type
-
+        return tp.args[0]
+    # GenericForeignKey
+    if tp.type.has_base(GENERIC_FOREIGN_KEY_FULLNAME):
+        return AnyType(TypeOfAny.special_form)
    return None


@@ -218,9 +205,7 @@ def extract_field_getter_type(tp: Instance) -> Optional[Type]:
    if not isinstance(tp, Instance):
        return None
    if tp.type.has_base(FIELD_FULLNAME):
-        get_method = tp.type.get_method('__get__')
-        if isinstance(get_method, FuncDef) and isinstance(get_method.type, CallableType):
-            return get_method.type.ret_type
+        return tp.args[1]
    # GenericForeignKey
    if tp.type.has_base(GENERIC_FOREIGN_KEY_FULLNAME):
        return AnyType(TypeOfAny.special_form)
@@ -240,7 +225,10 @@ def get_fields_metadata(model: TypeInfo) -> Dict[str, typing.Any]:
    return get_django_metadata(model).setdefault('fields', {})


-def extract_primary_key_type_for_set(model: TypeInfo) -> Optional[Type]:
+def extract_explicit_set_type_of_model_primary_key(model: TypeInfo) -> Optional[Type]:
+    """
+    If field with primary_key=True is set on the model, extract its __set__ type.
+    """
    for field_name, props in get_fields_metadata(model).items():
        is_primary_key = props.get('primary_key', False)
        if is_primary_key:
@@ -254,3 +242,30 @@ def extract_primary_key_type_for_get(model: TypeInfo) -> Optional[Type]:
        if is_primary_key:
            return extract_field_getter_type(model.names[field_name].type)
    return None
+
+
+def make_optional(typ: Type):
+    return UnionType.make_simplified_union([typ, NoneTyp()])
+
+
+def make_required(typ: Type) -> Type:
+    if not isinstance(typ, UnionType):
+        return typ
+    items = [item for item in typ.items if not isinstance(item, NoneTyp)]
+    # will reduce to Instance, if only one item
+    return UnionType.make_union(items)
+
+
+def is_optional(typ: Type) -> bool:
+    if not isinstance(typ, UnionType):
+        return False
+
+    return any([isinstance(item, NoneTyp) for item in typ.items])
+
+
+
+def has_any_of_bases(info: TypeInfo, bases: typing.Sequence[str]) -> bool:
+    for base_fullname in bases:
+        if info.has_base(base_fullname):
+            return True
+    return False
--- a/mypy_django_plugin/main.py
+++ b/mypy_django_plugin/main.py
@@ -1,19 +1,18 @@
 import os
-from typing import Callable, Dict, Optional, cast
+from typing import Callable, Dict, Optional, Union, cast

 from mypy.checker import TypeChecker
 from mypy.nodes import MemberExpr, TypeInfo
 from mypy.options import Options
 from mypy.plugin import AttributeContext, ClassDefContext, FunctionContext, MethodContext, Plugin
-from mypy.types import AnyType, Instance, Type, TypeOfAny, TypeType
+from mypy.types import AnyType, Instance, Type, TypeOfAny, TypeType, UnionType
 from mypy_django_plugin import helpers, monkeypatch
 from mypy_django_plugin.config import Config
-from mypy_django_plugin.plugins import init_create
-from mypy_django_plugin.plugins.fields import determine_type_of_array_field, record_field_properties_into_outer_model_class
-from mypy_django_plugin.plugins.migrations import determine_model_cls_from_string_for_migrations, get_string_value_from_expr
-from mypy_django_plugin.plugins.models import process_model_class
-from mypy_django_plugin.plugins.related_fields import extract_to_parameter_as_get_ret_type_for_related_field, reparametrize_with
-from mypy_django_plugin.plugins.settings import AddSettingValuesToDjangoConfObject, get_settings_metadata
+from mypy_django_plugin.transformers import fields, init_create
+from mypy_django_plugin.transformers.migrations import determine_model_cls_from_string_for_migrations, \
+    get_string_value_from_expr
+from mypy_django_plugin.transformers.models import process_model_class
+from mypy_django_plugin.transformers.settings import AddSettingValuesToDjangoConfObject, get_settings_metadata


 def transform_model_class(ctx: ClassDefContext) -> None:
@@ -50,7 +49,7 @@ def determine_proper_manager_type(ctx: FunctionContext) -> Type:
        if base.type.fullname() in {helpers.MANAGER_CLASS_FULLNAME,
                                    helpers.RELATED_MANAGER_CLASS_FULLNAME,
                                    helpers.BASE_MANAGER_CLASS_FULLNAME}:
-            ret.type.bases[i] = reparametrize_with(base, [Instance(outer_model_info, [])])
+            ret.type.bases[i] = Instance(base.type, [Instance(outer_model_info, [])])
            return ret
    return ret

@@ -84,6 +83,17 @@ def return_user_model_hook(ctx: FunctionContext) -> Type:
    return TypeType(Instance(model_info, []))


+def _extract_referred_to_type_info(typ: Union[UnionType, Instance]) -> Optional[TypeInfo]:
+    if isinstance(typ, Instance):
+        return typ.type
+    else:
+        # should be Union[TYPE, None]
+        typ = helpers.make_required(typ)
+        if isinstance(typ, Instance):
+            return typ.type
+    return None
+
+
 def extract_and_return_primary_key_of_bound_related_field_parameter(ctx: AttributeContext) -> Type:
    if not isinstance(ctx.default_attr_type, Instance) or not (ctx.default_attr_type.type.fullname() == 'builtins.int'):
        return ctx.default_attr_type
@@ -94,14 +104,22 @@ def extract_and_return_primary_key_of_bound_related_field_parameter(ctx: Attribu
    field_name = ctx.context.name.split('_')[0]
    sym = ctx.type.type.get(field_name)
    if sym and isinstance(sym.type, Instance) and len(sym.type.args) > 0:
-        to_arg = sym.type.args[0]
-        if isinstance(to_arg, AnyType):
-            return AnyType(TypeOfAny.special_form)
+        referred_to = sym.type.args[1]
+        if isinstance(referred_to, AnyType):
+            return AnyType(TypeOfAny.implementation_artifact)
+
+        model_type = _extract_referred_to_type_info(referred_to)
+        if model_type is None:
+            return AnyType(TypeOfAny.implementation_artifact)

-        model_type: TypeInfo = to_arg.type
        primary_key_type = helpers.extract_primary_key_type_for_get(model_type)
        if primary_key_type:
            return primary_key_type
+
+    is_nullable = helpers.get_fields_metadata(ctx.type.type).get(field_name, {}).get('null', False)
+    if is_nullable:
+        return helpers.make_optional(ctx.default_attr_type)
+
    return ctx.default_attr_type


@@ -179,26 +197,19 @@ class DjangoPlugin(Plugin):

    def get_function_hook(self, fullname: str
                          ) -> Optional[Callable[[FunctionContext], Type]]:
+        sym = self.lookup_fully_qualified(fullname)
+        if sym and isinstance(sym.node, TypeInfo) and sym.node.has_base(helpers.FIELD_FULLNAME):
+            return fields.adjust_return_type_of_field_instantiation
+
        if fullname == 'django.contrib.auth.get_user_model':
            return return_user_model_hook

-        if fullname in {helpers.FOREIGN_KEY_FULLNAME,
-                        helpers.ONETOONE_FIELD_FULLNAME,
-                        helpers.MANYTOMANY_FIELD_FULLNAME}:
-            return extract_to_parameter_as_get_ret_type_for_related_field
-
-        if fullname == 'django.contrib.postgres.fields.array.ArrayField':
-            return determine_type_of_array_field
-
        manager_bases = self._get_current_manager_bases()
        if fullname in manager_bases:
            return determine_proper_manager_type

        sym = self.lookup_fully_qualified(fullname)
        if sym and isinstance(sym.node, TypeInfo):
-            if sym.node.has_base(helpers.FIELD_FULLNAME):
-                return record_field_properties_into_outer_model_class
-
            if sym.node.metadata.get('django', {}).get('generated_init'):
                return init_create.redefine_and_typecheck_model_init

--- a/mypy_django_plugin/plugins/fields.py
+++ b/mypy_django_plugin/plugins/fields.py
@@ -1,74 +0,0 @@
-from typing import cast
-
-from mypy.checker import TypeChecker
-from mypy.nodes import ListExpr, NameExpr, TupleExpr
-from mypy.plugin import FunctionContext
-from mypy.types import Instance, TupleType, Type
-
-from mypy_django_plugin import helpers
-from mypy_django_plugin.plugins.models import iter_over_assignments
-
-
-def determine_type_of_array_field(ctx: FunctionContext) -> Type:
-    base_field_arg_type = helpers.get_argument_type_by_name(ctx, 'base_field')
-    if not base_field_arg_type or not isinstance(base_field_arg_type, Instance):
-        return ctx.default_return_type
-
-    get_method = base_field_arg_type.type.get_method('__get__')
-    if not get_method:
-        # not a method
-        return ctx.default_return_type
-
-    return ctx.api.named_generic_type(ctx.context.callee.fullname,
-                                      args=[get_method.type.ret_type])
-
-
-def record_field_properties_into_outer_model_class(ctx: FunctionContext) -> Type:
-    api = cast(TypeChecker, ctx.api)
-    outer_model = api.scope.active_class()
-    if outer_model is None or not outer_model.has_base(helpers.MODEL_CLASS_FULLNAME):
-        # outside models.Model class, undetermined
-        return ctx.default_return_type
-
-    field_name = None
-    for name_expr, stmt in iter_over_assignments(outer_model.defn):
-        if stmt == ctx.context and isinstance(name_expr, NameExpr):
-            field_name = name_expr.name
-            break
-    if field_name is None:
-        return ctx.default_return_type
-
-    fields_metadata = outer_model.metadata.setdefault('django', {}).setdefault('fields', {})
-
-    # primary key
-    is_primary_key = False
-    primary_key_arg = helpers.get_argument_by_name(ctx, 'primary_key')
-    if primary_key_arg:
-        is_primary_key = helpers.parse_bool(primary_key_arg)
-    fields_metadata[field_name] = {'primary_key': is_primary_key}
-
-    # choices
-    choices_arg = helpers.get_argument_by_name(ctx, 'choices')
-    if choices_arg and isinstance(choices_arg, (TupleExpr, ListExpr)):
-        # iterable of 2 element tuples of two kinds
-        _, analyzed_choices = api.analyze_iterable_item_type(choices_arg)
-        if isinstance(analyzed_choices, TupleType):
-            first_element_type = analyzed_choices.items[0]
-            if isinstance(first_element_type, Instance):
-                fields_metadata[field_name]['choices'] = first_element_type.type.fullname()
-
-    # nullability
-    null_arg = helpers.get_argument_by_name(ctx, 'null')
-    is_nullable = False
-    if null_arg:
-        is_nullable = helpers.parse_bool(null_arg)
-    fields_metadata[field_name]['null'] = is_nullable
-
-    # is_blankable
-    blank_arg = helpers.get_argument_by_name(ctx, 'blank')
-    is_blankable = False
-    if blank_arg:
-        is_blankable = helpers.parse_bool(blank_arg)
-    fields_metadata[field_name]['blank'] = is_blankable
-
-    return ctx.default_return_type
--- a/mypy_django_plugin/plugins/related_fields.py
+++ b/mypy_django_plugin/plugins/related_fields.py
@@ -1,62 +0,0 @@
-from typing import Optional, cast
-
-from mypy.checker import TypeChecker
-from mypy.nodes import StrExpr, TypeInfo
-from mypy.plugin import FunctionContext
-from mypy.types import CallableType, Instance, Type
-
-from mypy_django_plugin import helpers
-from mypy_django_plugin.helpers import fill_typevars_with_any, reparametrize_with
-
-
-def get_valid_to_value_or_none(ctx: FunctionContext) -> Optional[Instance]:
-    api = cast(TypeChecker, ctx.api)
-    if 'to' not in ctx.callee_arg_names:
-        # shouldn't happen, invalid code
-        api.msg.fail(f'to= parameter must be set for {ctx.context.callee.fullname}',
-                     context=ctx.context)
-        return None
-
-    arg_type = ctx.arg_types[ctx.callee_arg_names.index('to')][0]
-    if not isinstance(arg_type, CallableType):
-        to_arg_expr = ctx.args[ctx.callee_arg_names.index('to')][0]
-        if not isinstance(to_arg_expr, StrExpr):
-            # not string, not supported
-            return None
-        try:
-            model_fullname = helpers.get_model_fullname_from_string(to_arg_expr.value,
-                                                                    all_modules=api.modules)
-        except helpers.SelfReference:
-            model_fullname = api.tscope.classes[-1].fullname()
-
-        if model_fullname is None:
-            return None
-        model_info = helpers.lookup_fully_qualified_generic(model_fullname,
-                                                            all_modules=api.modules)
-        if model_info is None or not isinstance(model_info, TypeInfo):
-            return None
-        return Instance(model_info, [])
-
-    referred_to_type = arg_type.ret_type
-    if not isinstance(referred_to_type, Instance):
-        return None
-    if not referred_to_type.type.has_base(helpers.MODEL_CLASS_FULLNAME):
-        ctx.api.msg.fail(f'to= parameter value must be '
-                         f'a subclass of {helpers.MODEL_CLASS_FULLNAME}',
-                         context=ctx.context)
-        return None
-
-    return referred_to_type
-
-
-def extract_to_parameter_as_get_ret_type_for_related_field(ctx: FunctionContext) -> Type:
-    try:
-        referred_to_type = get_valid_to_value_or_none(ctx)
-    except helpers.InvalidModelString as exc:
-        ctx.api.fail(f'Invalid value for a to= parameter: {exc.model_string!r}', ctx.context)
-        return fill_typevars_with_any(ctx.default_return_type)
-
-    if referred_to_type is None:
-        # couldn't extract to= value
-        return fill_typevars_with_any(ctx.default_return_type)
-    return reparametrize_with(ctx.default_return_type, [referred_to_type])
--- a/mypy_django_plugin/transformers/init.py
+++ b/mypy_django_plugin/transformers/init.py
--- a/mypy_django_plugin/transformers/fields.py
+++ b/mypy_django_plugin/transformers/fields.py
@@ -0,0 +1,199 @@
+from typing import Optional, cast
+
+from mypy.checker import TypeChecker
+from mypy.nodes import ListExpr, NameExpr, StrExpr, TupleExpr, TypeInfo, Var
+from mypy.plugin import FunctionContext
+from mypy.types import AnyType, CallableType, Instance, TupleType, Type, TypeOfAny, UnionType
+from mypy_django_plugin import helpers
+from mypy_django_plugin.transformers.models import iter_over_assignments
+
+
+def get_valid_to_value_or_none(ctx: FunctionContext) -> Optional[Instance]:
+    api = cast(TypeChecker, ctx.api)
+    if 'to' not in ctx.callee_arg_names:
+        api.msg.fail(f'to= parameter must be set for {ctx.context.callee.fullname}',
+                     context=ctx.context)
+        return None
+
+    arg_type = ctx.arg_types[ctx.callee_arg_names.index('to')][0]
+    if not isinstance(arg_type, CallableType):
+        to_arg_expr = ctx.args[ctx.callee_arg_names.index('to')][0]
+        if not isinstance(to_arg_expr, StrExpr):
+            # not string, not supported
+            return None
+        try:
+            model_fullname = helpers.get_model_fullname_from_string(to_arg_expr.value,
+                                                                    all_modules=api.modules)
+        except helpers.SelfReference:
+            model_fullname = api.tscope.classes[-1].fullname()
+
+        if model_fullname is None:
+            return None
+        model_info = helpers.lookup_fully_qualified_generic(model_fullname,
+                                                            all_modules=api.modules)
+        if model_info is None or not isinstance(model_info, TypeInfo):
+            return None
+        return Instance(model_info, [])
+
+    referred_to_type = arg_type.ret_type
+    if not isinstance(referred_to_type, Instance):
+        return None
+    if not referred_to_type.type.has_base(helpers.MODEL_CLASS_FULLNAME):
+        ctx.api.msg.fail(f'to= parameter value must be '
+                         f'a subclass of {helpers.MODEL_CLASS_FULLNAME}',
+                         context=ctx.context)
+        return None
+
+    return referred_to_type
+
+
+def convert_any_to_type(typ: Type, referred_to_type: Type) -> Type:
+    if isinstance(typ, UnionType):
+        converted_items = []
+        for item in typ.items:
+            converted_items.append(convert_any_to_type(item, referred_to_type))
+        return UnionType.make_simplified_union(converted_items,
+                                               line=typ.line, column=typ.column)
+    if isinstance(typ, Instance):
+        args = []
+        for default_arg in typ.args:
+            if isinstance(default_arg, AnyType):
+                args.append(referred_to_type)
+            else:
+                args.append(default_arg)
+        return helpers.reparametrize_instance(typ, args)
+
+    if isinstance(typ, AnyType):
+        return referred_to_type
+
+    return typ
+
+
+def _extract_referred_to_type(ctx: FunctionContext) -> Optional[Type]:
+    try:
+        referred_to_type = get_valid_to_value_or_none(ctx)
+    except helpers.InvalidModelString as exc:
+        ctx.api.fail(f'Invalid value for a to= parameter: {exc.model_string!r}', ctx.context)
+        return None
+
+    return referred_to_type
+
+
+def fill_descriptor_types_for_related_field(ctx: FunctionContext) -> Type:
+    default_return_type = set_descriptor_types_for_field(ctx)
+    referred_to_type = _extract_referred_to_type(ctx)
+    if referred_to_type is None:
+        return default_return_type
+
+    # replace Any with referred_to_type
+    args = []
+    for default_arg in default_return_type.args:
+        args.append(convert_any_to_type(default_arg, referred_to_type))
+
+    return helpers.reparametrize_instance(ctx.default_return_type, new_args=args)
+
+
+def get_private_descriptor_type(type_info: TypeInfo, private_field_name: str, is_nullable: bool) -> Type:
+    node = type_info.get(private_field_name).node
+    if isinstance(node, Var):
+        descriptor_type = node.type
+        if is_nullable:
+            descriptor_type = helpers.make_optional(descriptor_type)
+        return descriptor_type
+    return AnyType(TypeOfAny.unannotated)
+
+
+def set_descriptor_types_for_field(ctx: FunctionContext) -> Instance:
+    default_return_type = cast(Instance, ctx.default_return_type)
+    is_nullable = helpers.parse_bool(helpers.get_argument_by_name(ctx, 'null'))
+
+    set_type = get_private_descriptor_type(default_return_type.type, '_pyi_private_set_type',
+                                           is_nullable=is_nullable)
+    get_type = get_private_descriptor_type(default_return_type.type, '_pyi_private_get_type',
+                                           is_nullable=is_nullable)
+    return helpers.reparametrize_instance(default_return_type, [set_type, get_type])
+
+
+def determine_type_of_array_field(ctx: FunctionContext) -> Type:
+    default_return_type = set_descriptor_types_for_field(ctx)
+
+    base_field_arg_type = helpers.get_argument_type_by_name(ctx, 'base_field')
+    if not base_field_arg_type or not isinstance(base_field_arg_type, Instance):
+        return default_return_type
+
+    base_type = base_field_arg_type.args[1]  # extract __get__ type
+    args = []
+    for default_arg in default_return_type.args:
+        args.append(convert_any_to_type(default_arg, base_type))
+
+    return helpers.reparametrize_instance(default_return_type, args)
+
+
+def transform_into_proper_return_type(ctx: FunctionContext) -> Type:
+    default_return_type = ctx.default_return_type
+    if not isinstance(default_return_type, Instance):
+        return default_return_type
+
+    if helpers.has_any_of_bases(default_return_type.type, (helpers.FOREIGN_KEY_FULLNAME,
+                                                           helpers.ONETOONE_FIELD_FULLNAME,
+                                                           helpers.MANYTOMANY_FIELD_FULLNAME)):
+        return fill_descriptor_types_for_related_field(ctx)
+
+    if default_return_type.type.has_base(helpers.ARRAY_FIELD_FULLNAME):
+        return determine_type_of_array_field(ctx)
+
+    return set_descriptor_types_for_field(ctx)
+
+
+def adjust_return_type_of_field_instantiation(ctx: FunctionContext) -> Type:
+    record_field_properties_into_outer_model_class(ctx)
+    return transform_into_proper_return_type(ctx)
+
+
+def record_field_properties_into_outer_model_class(ctx: FunctionContext) -> None:
+    api = cast(TypeChecker, ctx.api)
+    outer_model = api.scope.active_class()
+    if outer_model is None or not outer_model.has_base(helpers.MODEL_CLASS_FULLNAME):
+        # outside models.Model class, undetermined
+        return
+
+    field_name = None
+    for name_expr, stmt in iter_over_assignments(outer_model.defn):
+        if stmt == ctx.context and isinstance(name_expr, NameExpr):
+            field_name = name_expr.name
+            break
+    if field_name is None:
+        return
+
+    fields_metadata = outer_model.metadata.setdefault('django', {}).setdefault('fields', {})
+
+    # primary key
+    is_primary_key = False
+    primary_key_arg = helpers.get_argument_by_name(ctx, 'primary_key')
+    if primary_key_arg:
+        is_primary_key = helpers.parse_bool(primary_key_arg)
+    fields_metadata[field_name] = {'primary_key': is_primary_key}
+
+    # choices
+    choices_arg = helpers.get_argument_by_name(ctx, 'choices')
+    if choices_arg and isinstance(choices_arg, (TupleExpr, ListExpr)):
+        # iterable of 2 element tuples of two kinds
+        _, analyzed_choices = api.analyze_iterable_item_type(choices_arg)
+        if isinstance(analyzed_choices, TupleType):
+            first_element_type = analyzed_choices.items[0]
+            if isinstance(first_element_type, Instance):
+                fields_metadata[field_name]['choices'] = first_element_type.type.fullname()
+
+    # nullability
+    null_arg = helpers.get_argument_by_name(ctx, 'null')
+    is_nullable = False
+    if null_arg:
+        is_nullable = helpers.parse_bool(null_arg)
+    fields_metadata[field_name]['null'] = is_nullable
+
+    # is_blankable
+    blank_arg = helpers.get_argument_by_name(ctx, 'blank')
+    is_blankable = False
+    if blank_arg:
+        is_blankable = helpers.parse_bool(blank_arg)
+    fields_metadata[field_name]['blank'] = is_blankable
--- a/mypy_django_plugin/transformers/init_create.py
+++ b/mypy_django_plugin/transformers/init_create.py
@@ -3,10 +3,10 @@ from typing import Dict, Optional, Set, cast
 from mypy.checker import TypeChecker
 from mypy.nodes import TypeInfo, Var
 from mypy.plugin import FunctionContext, MethodContext
-from mypy.types import AnyType, Instance, Type, TypeOfAny, UnionType
-
+from mypy.types import AnyType, Instance, Type, TypeOfAny
 from mypy_django_plugin import helpers
-from mypy_django_plugin.helpers import extract_field_setter_type, extract_primary_key_type_for_set, get_fields_metadata
+from mypy_django_plugin.helpers import extract_field_setter_type, extract_explicit_set_type_of_model_primary_key, get_fields_metadata
+from mypy_django_plugin.transformers.fields import get_private_descriptor_type


 def extract_base_pointer_args(model: TypeInfo) -> Set[str]:
@@ -112,40 +112,54 @@ def extract_choices_type(model: TypeInfo, field_name: str) -> Optional[str]:


 def extract_expected_types(ctx: FunctionContext, model: TypeInfo) -> Dict[str, Type]:
-    expected_types: Dict[str, Type] = {}
+    api = cast(TypeChecker, ctx.api)

-    primary_key_type = extract_primary_key_type_for_set(model)
+    expected_types: Dict[str, Type] = {}
+    primary_key_type = extract_explicit_set_type_of_model_primary_key(model)
    if not primary_key_type:
        # no explicit primary key, set pk to Any and add id
        primary_key_type = AnyType(TypeOfAny.special_form)
        expected_types['id'] = ctx.api.named_generic_type('builtins.int', [])
-
    expected_types['pk'] = primary_key_type
+
    for base in model.mro:
+        # extract all fields for all models in MRO
        for name, sym in base.names.items():
            # do not redefine special attrs
            if name in {'_meta', 'pk'}:
                continue
+
            if isinstance(sym.node, Var):
-                if sym.node.type is None or isinstance(sym.node.type, AnyType):
+                typ = sym.node.type
+                if typ is None or isinstance(typ, AnyType):
                    # types are not ready, fallback to Any
                    expected_types[name] = AnyType(TypeOfAny.from_unimported_type)
                    expected_types[name + '_id'] = AnyType(TypeOfAny.from_unimported_type)

-                elif isinstance(sym.node.type, Instance):
-                    tp = sym.node.type
-                    field_type = extract_field_setter_type(tp)
+                elif isinstance(typ, Instance):
+                    field_type = extract_field_setter_type(typ)
                    if field_type is None:
                        continue

-                    if tp.type.fullname() in {helpers.FOREIGN_KEY_FULLNAME, helpers.ONETOONE_FIELD_FULLNAME}:
-                        ref_to_model = tp.args[0]
-                        primary_key_type = AnyType(TypeOfAny.special_form)
-                        if isinstance(ref_to_model, Instance) and ref_to_model.type.has_base(helpers.MODEL_CLASS_FULLNAME):
-                            typ = extract_primary_key_type_for_set(ref_to_model.type)
-                            if typ:
-                                primary_key_type = typ
+                    if typ.type.fullname() in {helpers.FOREIGN_KEY_FULLNAME, helpers.ONETOONE_FIELD_FULLNAME}:
+                        primary_key_type = AnyType(TypeOfAny.implementation_artifact)
+                        # in case it's optional, we need Instance type
+                        referred_to_model = typ.args[1]
+                        is_nullable = helpers.is_optional(referred_to_model)
+                        if is_nullable:
+                            referred_to_model = helpers.make_required(typ.args[1])
+
+                        if isinstance(referred_to_model, Instance) and referred_to_model.type.has_base(helpers.MODEL_CLASS_FULLNAME):
+                            pk_type = extract_explicit_set_type_of_model_primary_key(referred_to_model.type)
+                            if not pk_type:
+                                # extract set type of AutoField
+                                autofield_info = api.lookup_typeinfo('django.db.models.fields.AutoField')
+                                pk_type = get_private_descriptor_type(autofield_info, '_pyi_private_set_type',
+                                                                      is_nullable=is_nullable)
+                            primary_key_type = pk_type
+
                        expected_types[name + '_id'] = primary_key_type
+
                    if field_type:
                        expected_types[name] = field_type

--- a/mypy_django_plugin/transformers/migrations.py
+++ b/mypy_django_plugin/transformers/migrations.py
@@ -4,7 +4,6 @@ from mypy.checker import TypeChecker
 from mypy.nodes import Expression, StrExpr, TypeInfo
 from mypy.plugin import MethodContext
 from mypy.types import Instance, Type, TypeType
-
 from mypy_django_plugin import helpers


--- a/mypy_django_plugin/transformers/models.py
+++ b/mypy_django_plugin/transformers/models.py
@@ -73,8 +73,6 @@ def iter_over_one_to_n_related_fields(klass: ClassDef) -> Iterator[Tuple[NameExp
 class SetIdAttrsForRelatedFields(ModelClassInitializer):
    def run(self) -> None:
        for lvalue, rvalue in iter_over_one_to_n_related_fields(self.model_classdef):
-            # base_model_info = self.api.named_type('builtins.object').type
-            # helpers.get_related_field_primary_key_names(base_model_info).append(node_name)
            node_name = lvalue.name + '_id'
            self.add_new_node_to_model_class(name=node_name,
                                             typ=self.api.builtin_type('builtins.int'))
--- a/mypy_django_plugin/transformers/settings.py
+++ b/mypy_django_plugin/transformers/settings.py
--- a/scripts/typecheck_tests.py
+++ b/scripts/typecheck_tests.py
@@ -227,7 +227,7 @@ IGNORED_ERRORS = {
    ],
    'postgres_tests': [
        'Cannot assign multiple types to name',
-        'Incompatible types in assignment (expression has type "Type[Field]',
+        'Incompatible types in assignment (expression has type "Type[Field[Any, Any]]',
        'DummyArrayField',
        'DummyJSONField',
        'Argument "encoder" to "JSONField" has incompatible type "DjangoJSONEncoder"; expected "Optional[Type[JSONEncoder]]"',
--- a/test-data/plugins.ini
+++ b/test-data/plugins.ini
@@ -1,4 +1,5 @@
 [mypy]
-incremental = False
+incremental = True
+strict_optional = True
 plugins =
    mypy_django_plugin.main
--- a/test-data/typecheck/fields.test
+++ b/test-data/typecheck/fields.test
@@ -6,7 +6,7 @@ class User(models.Model):
    array = ArrayField(base_field=models.Field())

 user = User()
-reveal_type(user.array)  # E: Revealed type is 'builtins.list[Any]'
+reveal_type(user.array)  # E: Revealed type is 'builtins.list*[Any]'

 [CASE array_field_base_field_parsed_into_generic_typevar]
 from django.db import models
@@ -17,8 +17,8 @@ class User(models.Model):
    members_as_text = ArrayField(base_field=models.CharField(max_length=255))

 user = User()
-reveal_type(user.members)  # E: Revealed type is 'builtins.list[builtins.int*]'
-reveal_type(user.members_as_text)  # E: Revealed type is 'builtins.list[builtins.str*]'
+reveal_type(user.members)  # E: Revealed type is 'builtins.list*[builtins.int]'
+reveal_type(user.members_as_text)  # E: Revealed type is 'builtins.list*[builtins.str]'

 [CASE test_model_fields_classes_present_as_primitives]
 from django.db import models
@@ -31,13 +31,13 @@ class User(models.Model):
    text = models.TextField()

 user = User()
-reveal_type(user.id)  # E: Revealed type is 'builtins.int'
-reveal_type(user.small_int)  # E: Revealed type is 'builtins.int'
-reveal_type(user.name)  # E: Revealed type is 'builtins.str'
-reveal_type(user.slug)  # E: Revealed type is 'builtins.str'
-reveal_type(user.text)  # E: Revealed type is 'builtins.str'
+reveal_type(user.id)  # E: Revealed type is 'builtins.int*'
+reveal_type(user.small_int)  # E: Revealed type is 'builtins.int*'
+reveal_type(user.name)  # E: Revealed type is 'builtins.str*'
+reveal_type(user.slug)  # E: Revealed type is 'builtins.str*'
+reveal_type(user.text)  # E: Revealed type is 'builtins.str*'

-[CASE test_model_field_classes_from_exciting_locations]
+[CASE test_model_field_classes_from_existing_locations]
 from django.db import models
 from django.contrib.postgres import fields as pg_fields
 from decimal import Decimal
@@ -48,9 +48,9 @@ class Booking(models.Model):
    some_decimal = models.DecimalField(max_digits=10, decimal_places=5)

 booking = Booking()
-reveal_type(booking.id)  # E: Revealed type is 'builtins.int'
+reveal_type(booking.id)  # E: Revealed type is 'builtins.int*'
 reveal_type(booking.time_range)  # E: Revealed type is 'Any'
-reveal_type(booking.some_decimal)  # E: Revealed type is 'decimal.Decimal'
+reveal_type(booking.some_decimal)  # E: Revealed type is 'decimal.Decimal*'

 [CASE test_add_id_field_if_no_primary_key_defined]
 from django.db import models
@@ -66,7 +66,7 @@ from django.db import models
 class User(models.Model):
    my_pk = models.IntegerField(primary_key=True)

-reveal_type(User().my_pk)  # E: Revealed type is 'builtins.int'
+reveal_type(User().my_pk)  # E: Revealed type is 'builtins.int*'
 reveal_type(User().id)  # E: Revealed type is 'Any'
 [out]

@@ -102,5 +102,5 @@ class ParentModel(models.Model):
    pass
 class MyModel(ParentModel):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
-reveal_type(MyModel().id)  # E: Revealed type is 'uuid.UUID'
+reveal_type(MyModel().id)  # E: Revealed type is 'uuid.UUID*'
 [out]
--- a/test-data/typecheck/model_create.test
+++ b/test-data/typecheck/model_create.test
@@ -31,4 +31,15 @@ class Child1(Parent1, Parent2):
    value = models.IntegerField()
 class Child4(Child1):
    value4 = models.IntegerField()
-Child4.objects.create(name1='n1', name2='n2', value=1, value4=4)
+Child4.objects.create(name1='n1', name2='n2', value=1, value4=4)
+
+[CASE create_through_related_manager_of_manytomany_field]
+from django.db import models
+
+class Publication(models.Model):
+    title = models.CharField(max_length=100)
+class Article(models.Model):
+    publications = models.ManyToManyField(Publication)
+article = Article.objects.create()
+article.publications.create(title='my title')
+[out]
--- a/test-data/typecheck/model_init.test
+++ b/test-data/typecheck/model_init.test
@@ -71,14 +71,15 @@ from django.db import models

 class Publisher(models.Model):
    pass
-class PublisherWithCharPK(models.Model):
-    id = models.IntegerField(primary_key=True)
+class PublisherDatetime(models.Model):
+    dt_pk = models.DateTimeField(primary_key=True)
 class Book(models.Model):
    publisher = models.ForeignKey(Publisher, on_delete=models.CASCADE)
-    publisher_with_char_pk = models.ForeignKey(PublisherWithCharPK, on_delete=models.CASCADE)
+    publisher_dt = models.ForeignKey(PublisherDatetime, on_delete=models.CASCADE)

-Book(publisher_id=1, publisher_with_char_pk_id=1)
-Book(publisher_id=1, publisher_with_char_pk_id='hello')  # E: Incompatible type for "publisher_with_char_pk_id" of "Book" (got "str", expected "Union[int, Combinable, Literal['']]")
+Book(publisher_id=1)
+Book(publisher_id=[])  # E: Incompatible type for "publisher_id" of "Book" (got "List[Any]", expected "Union[Combinable, int, str]")
+Book(publisher_dt_id=11)  # E: Incompatible type for "publisher_dt_id" of "Book" (got "int", expected "Union[str, date, datetime, Combinable]")
 [out]

 [CASE setting_value_to_an_array_of_ints]
@@ -94,7 +95,7 @@ MyModel(array=array_val)
 array_val2: List[int] = [1]
 MyModel(array=array_val2)
 array_val3: List[str] = ['hello']
-MyModel(array=array_val3)  # E: Incompatible type for "array" of "MyModel" (got "List[str]", expected "Sequence[int]")
+MyModel(array=array_val3)  # E: Incompatible type for "array" of "MyModel" (got "List[str]", expected "Union[Sequence[int], Combinable]")
 [out]

 [CASE if_no_explicit_primary_key_id_can_be_passed]
@@ -135,20 +136,6 @@ Restaurant(place_ptr=place)
 Restaurant(place_ptr_id=place.id)
 [out]

-[CASE extract_type_of_init_param_from_set_method]
-from typing import Union
-from datetime import time
-
-from django.db import models
-class MyField(models.Field):
-    def __set__(self, instance, value: Union[str, time]) -> None: pass
-    def __get__(self, instance, owner) -> time: pass
-class MyModel(models.Model):
-    field = MyField()
-MyModel(field=time())
-MyModel(field='12:00')
-MyModel(field=100)  # E: Incompatible type for "field" of "MyModel" (got "int", expected "Union[str, time]")
-
 [CASE charfield_with_integer_choices]
 from django.db import models
 class MyModel(models.Model):
--- a/test-data/typecheck/nullable_fields.test
+++ b/test-data/typecheck/nullable_fields.test
@@ -0,0 +1,42 @@
+[CASE nullable_field_with_strict_optional_true]
+from django.db import models
+class MyModel(models.Model):
+    text_nullable = models.CharField(max_length=100, null=True)
+    text = models.CharField(max_length=100)
+reveal_type(MyModel().text)  # E: Revealed type is 'builtins.str*'
+reveal_type(MyModel().text_nullable)  # E: Revealed type is 'Union[builtins.str, None]'
+MyModel().text = None  # E: Incompatible types in assignment (expression has type "None", variable has type "Union[str, int, Combinable]")
+MyModel().text_nullable = None
+[out]
+
+[CASE nullable_array_field]
+from django.db import models
+from django.contrib.postgres.fields import ArrayField
+
+class MyModel(models.Model):
+    lst = ArrayField(base_field=models.CharField(max_length=100), null=True)
+reveal_type(MyModel().lst)  # E: Revealed type is 'Union[builtins.list[builtins.str], None]'
+[out]
+
+[CASE nullable_foreign_key]
+from django.db import models
+
+class Publisher(models.Model):
+    pass
+class Book(models.Model):
+    publisher = models.ForeignKey(to=Publisher, on_delete=models.CASCADE, null=True)
+reveal_type(Book().publisher)  # E: Revealed type is 'Union[main.Publisher, None]'
+Book().publisher = 11  # E: Incompatible types in assignment (expression has type "int", variable has type "Union[Publisher, Combinable, None]")
+[out]
+
+[CASE nullable_self_foreign_key]
+from django.db import models
+class Inventory(models.Model):
+    parent = models.ForeignKey('self', on_delete=models.SET_NULL, null=True)
+parent = Inventory()
+core = Inventory(parent_id=parent.id)
+reveal_type(core.parent_id)  # E: Revealed type is 'Union[builtins.int, None]'
+reveal_type(core.parent)  # E: Revealed type is 'Union[main.Inventory, None]'
+Inventory(parent=None)
+Inventory(parent_id=None)
+[out]
--- a/test-data/typecheck/related_fields.test
+++ b/test-data/typecheck/related_fields.test
@@ -198,7 +198,7 @@ class App(models.Model):
    pass
 class Member(models.Model):
    apps = models.ManyToManyField(to=App, related_name='members')
-reveal_type(Member().apps)  # E: Revealed type is 'django.db.models.manager.RelatedManager[main.App*]'
+reveal_type(Member().apps)  # E: Revealed type is 'django.db.models.manager.RelatedManager*[main.App]'
 reveal_type(App().members)  # E: Revealed type is 'django.db.models.manager.RelatedManager[main.Member]'
 [out]

@@ -207,7 +207,7 @@ from django.db import models
 from myapp.models import App
 class Member(models.Model):
    apps = models.ManyToManyField(to='myapp.App', related_name='members')
-reveal_type(Member().apps)  # E: Revealed type is 'django.db.models.manager.RelatedManager[myapp.models.App*]'
+reveal_type(Member().apps)  # E: Revealed type is 'django.db.models.manager.RelatedManager*[myapp.models.App]'

 [file myapp/__init__.py]
 [file myapp/models.py]
@@ -226,8 +226,8 @@ reveal_type(User().parent)  # E: Revealed type is 'main.User*'
 [CASE many_to_many_with_self]
 from django.db import models
 class User(models.Model):
-    friends = models.ManyToManyField('self', on_delete=models.CASCADE)
-reveal_type(User().friends)  # E: Revealed type is 'django.db.models.manager.RelatedManager[main.User*]'
+    friends = models.ManyToManyField('self')
+reveal_type(User().friends)  # E: Revealed type is 'django.db.models.manager.RelatedManager*[main.User]'
 [out]

 [CASE recursively_checking_for_base_model_in_to_parameter]
@@ -274,4 +274,4 @@ Book2(publisher_id=1)
 Book2(publisher_id='hello')  # E: Incompatible type for "publisher_id" of "Book2" (got "str", expected "Union[int, Combinable, Literal['']]")
 Book2.objects.create(publisher_id=1)
 Book2.objects.create(publisher_id='hello')  # E: Incompatible type for "publisher_id" of "Book2" (got "str", expected "Union[int, Combinable, Literal['']]")
-[out]
+[out]