forms/formsets: Improve types (#271)

- Adds more specific types to all code in `django-stubs/forms/formsets.pyi`.
- Removes unnecessary assignments from module and class properties.
- `BaseFormSet` is now a generic class which contains a form type.

django-stubs/contrib/admin/views/main.pyi

@@ -12,6 +12,7 @@ from django.db.models.expressions import Combinable, CombinedExpression, OrderBy
 from django.db.models.options import Options
 from django.db.models.query import QuerySet
 from django.forms.formsets import BaseFormSet
+from django.forms.models import ModelForm
 
 ALL_VAR: str
 ORDER_VAR: str
@@ -47,7 +48,7 @@ class ChangeList:
     queryset: Any = ...
     title: Any = ...
     pk_attname: Any = ...
-    formset: BaseFormSet | None
+    formset: BaseFormSet[ModelForm] | None
     def __init__(
         self,
         request: WSGIRequest,

django-stubs/forms/formsets.pyi

@@ -1,90 +1,125 @@
-from collections.abc import Mapping, Sequence, Sized
-from typing import Any
+from collections.abc import Iterator
+from typing import Any, Generic, TypeVar
 
-from django.forms import Form
+from django.forms import BaseForm, Form
+from django.forms.renderers import BaseRenderer
+from django.forms.utils import ErrorDict, ErrorList, RenderableFormMixin
+from django.forms.widgets import CheckboxInput, Media, NumberInput, Widget
 
-TOTAL_FORM_COUNT: str = ...
-INITIAL_FORM_COUNT: str = ...
-MIN_NUM_FORM_COUNT: str = ...
-MAX_NUM_FORM_COUNT: str = ...
-ORDERING_FIELD_NAME: str = ...
-DELETION_FIELD_NAME: str = ...
+TOTAL_FORM_COUNT: str
+INITIAL_FORM_COUNT: str
+MIN_NUM_FORM_COUNT: str
+MAX_NUM_FORM_COUNT: str
+ORDERING_FIELD_NAME: str
+DELETION_FIELD_NAME: str
 
-DEFAULT_MIN_NUM: int = ...
-DEFAULT_MAX_NUM: int = ...
+DEFAULT_MIN_NUM: int
+DEFAULT_MAX_NUM: int
 
-class ManagementForm(Form):
-    cleaned_data: dict[str, int | None]
+_BaseFormT = TypeVar("_BaseFormT", bound=BaseForm)
+
+class ManagementForm(Form): ...
+
+class BaseFormSet(Generic[_BaseFormT], RenderableFormMixin):
+    deletion_widget: type[CheckboxInput]
+    ordering_widget: type[NumberInput]
+    default_error_messages: dict[str, str]
+    template_name_div: str
+    template_name_p: str
+    template_name_table: str
+    template_name_ul: str
+
+    is_bound: bool
+    prefix: str
+    auto_id: str
+    data: dict[str, Any]
+    files: dict[str, Any]
+    initial: dict[str, Any] | None
+    form_kwargs: dict[str, Any]
+    error_class: type[ErrorList]
+    error_messages: dict[str, Any]
 
-class BaseFormSet(Sized, Mapping[str, Any]):
-    is_bound: Any = ...
-    prefix: Any = ...
-    auto_id: Any = ...
-    data: Any = ...
-    files: Any = ...
-    initial: Any = ...
-    form_kwargs: Any = ...
-    error_class: Any = ...
     def __init__(
         self,
-        data: Any | None = ...,
-        files: Any | None = ...,
+        data: dict[str, Any] | None = ...,
+        files: dict[str, Any] | None = ...,
         auto_id: str = ...,
-        prefix: Any | None = ...,
-        initial: Any | None = ...,
-        error_class: Any = ...,
-        form_kwargs: Any | None = ...,
+        prefix: str | None = ...,
+        initial: dict[str, Any] | None = ...,
+        error_class: type[ErrorList] = ...,
+        form_kwargs: dict[str, Any] | None = ...,
+        error_messages: dict[str, Any] | None = ...,
     ) -> None: ...
-    def __iter__(self) -> Any: ...
-    def __getitem__(self, index: Any) -> Any: ...
-    def __len__(self) -> Any: ...
-    def __bool__(self) -> Any: ...
-    def management_form(self) -> Any: ...
-    def total_form_count(self) -> Any: ...
-    def initial_form_count(self) -> Any: ...
+    def __iter__(self) -> Iterator[_BaseFormT]: ...
+    def __getitem__(self, index: int) -> _BaseFormT: ...
+    def __len__(self) -> int: ...
+    def __bool__(self) -> bool: ...
+    @property
+    def management_form(self) -> ManagementForm: ...
+    def total_form_count(self) -> int: ...
+    def initial_form_count(self) -> int: ...
     @property
-    def forms(self) -> Any: ...
-    def get_form_kwargs(self, index: Any) -> Any: ...
+    def forms(self) -> list[_BaseFormT]: ...
+    def get_form_kwargs(self, index: int) -> dict[str, Any]: ...
     @property
-    def initial_forms(self) -> Any: ...
+    def initial_forms(self) -> list[_BaseFormT]: ...
     @property
-    def extra_forms(self) -> Any: ...
+    def extra_forms(self) -> list[_BaseFormT]: ...
     @property
-    def empty_form(self) -> Any: ...
+    def empty_form(self) -> _BaseFormT: ...
     @property
-    def cleaned_data(self) -> Any: ...
+    def cleaned_data(self) -> list[dict[str, Any]]: ...
     @property
-    def deleted_forms(self) -> Any: ...
+    def deleted_forms(self) -> list[_BaseFormT]: ...
     @property
-    def ordered_forms(self) -> Any: ...
+    def ordered_forms(self) -> list[_BaseFormT]: ...
     @classmethod
-    def get_default_prefix(cls) -> Any: ...
-    def non_form_errors(self) -> Any: ...
+    def get_default_prefix(cls) -> str: ...
+    @classmethod
+    def get_deletion_widget(cls) -> type[Widget]: ...
+    @classmethod
+    def get_ordering_widget(cls) -> type[Widget]: ...
+    def non_form_errors(self) -> ErrorList: ...
     @property
-    def errors(self) -> Any: ...
-    def total_error_count(self) -> Any: ...
-    def is_valid(self) -> Any: ...
-    def full_clean(self) -> Any: ...
+    def errors(self) -> list[ErrorDict]: ...
+    def total_error_count(self) -> int: ...
+    def is_valid(self) -> bool: ...
+    def full_clean(self) -> None: ...
     def clean(self) -> None: ...
-    def has_changed(self) -> Any: ...
-    def add_fields(self, form: Any, index: Any) -> None: ...
-    def add_prefix(self, index: Any) -> Any: ...
-    def is_multipart(self) -> Any: ...
+    def has_changed(self) -> bool: ...
+    def add_fields(self, form: _BaseFormT, index: int) -> None: ...
+    def add_prefix(self, index: int) -> str: ...
+    def is_multipart(self) -> bool: ...
     @property
-    def media(self) -> Any: ...
-    def as_table(self) -> Any: ...
-    def as_p(self) -> Any: ...
-    def as_ul(self) -> Any: ...
+    def media(self) -> Media: ...
+    def get_context(self) -> dict[str, Any]: ...
+
+# Dynamic class produced by formset_factory
+class _FormSet(BaseFormSet[_BaseFormT]):
+    form: type[_BaseFormT]
+    extra: int
+    can_order: bool
+    can_delete: bool
+    can_delete_extra: bool
+    min_num: int
+    max_num: int
+    absolute_max: int
+    validate_min: bool
+    validate_max: bool
+    renderer: BaseRenderer
 
 def formset_factory(
-    form: Any,
-    formset: Any = ...,
+    form: _BaseFormT,
+    formset: type[BaseFormSet[_BaseFormT]] = ...,
     extra: int = ...,
     can_order: bool = ...,
     can_delete: bool = ...,
-    max_num: Any | None = ...,
+    max_num: int | None = ...,
     validate_max: bool = ...,
-    min_num: Any | None = ...,
+    min_num: int | None = ...,
     validate_min: bool = ...,
-) -> Any: ...
-def all_valid(formsets: Sequence[Any]) -> bool: ...
+    absolute_max: int | None = ...,
+    can_delete_extra: bool = ...,
+    renderer: BaseRenderer | None = ...,
+) -> type[_FormSet[_BaseFormT]]: ...
+def all_valid(formsets: Iterator[BaseFormSet[Any]]) -> bool: ...

django-stubs/forms/models.pyi

@@ -115,7 +115,7 @@ def modelform_factory(
     field_classes: MutableMapping[str, type[Field]] | None = ...,
 ) -> type[ModelForm]: ...
 
-class BaseModelFormSet(BaseFormSet):
+class BaseModelFormSet(BaseFormSet[ModelForm]):
     model: Any = ...
     unique_fields: Any = ...
     queryset: Any = ...