Forms and exceptions improvements (#259)

- Removed some unnecessary `= ...` on class attributes ([see typing docs](https://typing.readthedocs.io/en/latest/guides/writing_stubs.html#classes))
- Added new exceptions to `django.core.exceptions`
- Added more specific types to `ValidationError`
- Gave `BaseForm` its parent class and made **`BaseForm.fields` more specific**
- Moved the `_meta` attribute from `BaseForm` to `ModelForm`
- Gave `Form` its metaclass and marked its attributes as class variables
- Improved type for `ModelFormOptions.formfield_callback`
- `forms.utils`: Added new classes, polished types on existing ones

django-stubs/core/exceptions.pyi

@@ -1,8 +1,6 @@
 from collections.abc import Iterator, Mapping
 from typing import Any
 
-from django.forms.utils import ErrorDict
-
 class FieldDoesNotExist(Exception): ...
 class AppRegistryNotReady(Exception): ...
 
@@ -16,6 +14,7 @@ class SuspiciousFileOperation(SuspiciousOperation): ...
 class DisallowedHost(SuspiciousOperation): ...
 class DisallowedRedirect(SuspiciousOperation): ...
 class TooManyFieldsSent(SuspiciousOperation): ...
+class TooManyFilesSent(SuspiciousOperation): ...
 class RequestDataTooBig(SuspiciousOperation): ...
 class RequestAborted(Exception): ...
 class BadRequest(Exception): ...
@@ -28,14 +27,19 @@ class FieldError(Exception): ...
 NON_FIELD_ERRORS: str
 
 class ValidationError(Exception):
-    error_dict: Any = ...
-    error_list: Any = ...
-    message: Any = ...
-    code: Any = ...
-    params: Any = ...
+    error_dict: dict[str, list[ValidationError]] | None
+    error_list: list[ValidationError] | None
+    message: str | None
+    code: str | None
+    params: Mapping[str, Any] | None
     def __init__(
         self,
-        message: Any,
+        message: (
+            ValidationError
+            | dict[str, ValidationError | list[str]]
+            | list[ValidationError | str]
+            | str
+        ),
         code: str | None = ...,
         params: Mapping[str, Any] | None = ...,
     ) -> None: ...
@@ -44,9 +48,10 @@ class ValidationError(Exception):
     @property
     def messages(self) -> list[str]: ...
     def update_error_dict(
-        self, error_dict: Mapping[str, Any]
-    ) -> dict[str, list[ValidationError]] | ErrorDict: ...
-    def __iter__(self) -> Iterator[tuple[str, list[str]] | str]: ...
+        self, error_dict: Mapping[str, list[ValidationError]]
+    ) -> Mapping[str, list[ValidationError]]: ...
+    def __iter__(self) -> Iterator[tuple[str, list[ValidationError]] | str]: ...
 
 class EmptyResultSet(Exception): ...
+class FullResultSet(Exception): ...
 class SynchronousOnlyOperation(Exception): ...

django-stubs/forms/forms.pyi

@@ -1,36 +1,34 @@
 from collections.abc import Iterator, Mapping
-from typing import Any
+from typing import Any, ClassVar
 
 from django.core.exceptions import ValidationError as ValidationError
 from django.core.files import uploadedfile
-from django.db.models.options import Options
 from django.forms.boundfield import BoundField
 from django.forms.fields import Field
 from django.forms.renderers import BaseRenderer
-from django.forms.utils import ErrorDict, ErrorList
+from django.forms.utils import ErrorDict, ErrorList, RenderableFormMixin
 from django.forms.widgets import Media, MediaDefiningClass
 from django.utils.datastructures import MultiValueDict
 from django.utils.safestring import SafeText
 
 class DeclarativeFieldsMetaclass(MediaDefiningClass): ...
 
-class BaseForm:
-    _meta: Options[Any]
-    default_renderer: type[BaseRenderer] = ...
-    field_order: list[str] | None = ...
-    use_required_attribute: bool = ...
-    is_bound: bool = ...
-    data: dict[str, Any] = ...
-    files: MultiValueDict[str, uploadedfile.UploadedFile] = ...
-    auto_id: bool | str = ...
-    initial: dict[str, Any] = ...
-    error_class: type[ErrorList] = ...
-    prefix: str | None = ...
-    label_suffix: str = ...
-    empty_permitted: bool = ...
-    fields: dict[str, Any] = ...
-    renderer: BaseRenderer = ...
-    cleaned_data: dict[str, Any] = ...
+class BaseForm(RenderableFormMixin):
+    default_renderer: type[BaseRenderer]
+    field_order: list[str] | None
+    use_required_attribute: bool
+    is_bound: bool
+    data: dict[str, Any]
+    files: MultiValueDict[str, uploadedfile.UploadedFile]
+    auto_id: bool | str
+    initial: dict[str, Any]
+    error_class: type[ErrorList]
+    prefix: str | None
+    label_suffix: str
+    empty_permitted: bool
+    fields: dict[str, Field]
+    renderer: BaseRenderer
+    cleaned_data: dict[str, Any]
     def __init__(
         self,
         data: Mapping[str, Any] | None = ...,
@@ -53,9 +51,6 @@ class BaseForm:
     def is_valid(self) -> bool: ...
     def add_prefix(self, field_name: str) -> str: ...
     def add_initial_prefix(self, field_name: str) -> str: ...
-    def as_table(self) -> SafeText: ...
-    def as_ul(self) -> SafeText: ...
-    def as_p(self) -> SafeText: ...
     def non_field_errors(self) -> ErrorList: ...
     def add_error(self, field: str | None, error: ValidationError | str) -> None: ...
     def has_error(self, field: str, code: str | None = ...) -> bool: ...
@@ -79,6 +74,6 @@ class BaseForm:
         errors_on_separate_row: bool,
     ) -> SafeText: ...
 
-class Form(BaseForm):
-    base_fields: dict[str, Field]
-    declared_fields: dict[str, Field]
+class Form(BaseForm, metaclass=DeclarativeFieldsMetaclass):
+    base_fields: ClassVar[dict[str, Field]]
+    declared_fields: ClassVar[dict[str, Field]]

django-stubs/forms/models.pyi

@@ -7,7 +7,7 @@ from collections.abc import (
     Sequence,
 )
 from datetime import datetime
-from typing import Any, ClassVar, TypeVar
+from typing import Any, ClassVar, Protocol, TypeVar
 from typing_extensions import Literal
 from unittest.mock import MagicMock
 from uuid import UUID
@@ -33,6 +33,11 @@ _ErrorMessages = dict[str, dict[str, str]]
 
 _M = TypeVar("_M", bound=Model)
 
+# Modeled from example:
+# https://docs.djangoproject.com/en/4.2/topics/forms/modelforms/#overriding-the-default-fields
+class FormFieldCallback(Protocol):
+    def __call__(self, db_field: models.Field[Any, Any], **kwargs: Any) -> Field: ...
+
 def construct_instance(
     form: BaseForm,
     instance: _M,
@@ -42,12 +47,13 @@ def construct_instance(
 def model_to_dict(
     instance: Model, fields: _Fields | None = ..., exclude: _Fields | None = ...
 ) -> dict[str, Any]: ...
+def apply_limit_choices_to_to_formfield(formfield: Field) -> None: ...
 def fields_for_model(
     model: type[Model],
     fields: _Fields | None = ...,
     exclude: _Fields | None = ...,
     widgets: dict[str, type[Input]] | dict[str, Widget] | None = ...,
-    formfield_callback: Callable[..., Any] | str | None = ...,
+    formfield_callback: FormFieldCallback | None = ...,
     localized_fields: tuple[str] | str | None = ...,
     labels: _Labels | None = ...,
     help_texts: dict[str, str] | None = ...,
@@ -58,15 +64,16 @@ def fields_for_model(
 ) -> dict[str, Any]: ...
 
 class ModelFormOptions:
-    model: type[Model] | None = ...
-    fields: _Fields | None = ...
-    exclude: _Fields | None = ...
-    widgets: dict[str, Widget | Input] | None = ...
-    localized_fields: tuple[str] | str | None = ...
-    labels: _Labels | None = ...
-    help_texts: dict[str, str] | None = ...
-    error_messages: _ErrorMessages | None = ...
-    field_classes: dict[str, type[Field]] | None = ...
+    model: type[Model] | None
+    fields: _Fields | None
+    exclude: _Fields | None
+    widgets: dict[str, Widget | Input] | None
+    localized_fields: tuple[str] | str | None
+    labels: _Labels | None
+    help_texts: dict[str, str] | None
+    error_messages: _ErrorMessages | None
+    field_classes: dict[str, type[Field]] | None
+    formfield_callback: FormFieldCallback | None
     def __init__(self, options: type | None = ...) -> None: ...
 
 class ModelFormMetaclass(DeclarativeFieldsMetaclass): ...
@@ -92,7 +99,7 @@ class BaseModelForm(BaseForm):
     def save(self, commit: bool = ...) -> Any: ...
 
 class ModelForm(BaseModelForm, metaclass=ModelFormMetaclass):
-    base_fields: ClassVar[dict[str, Field]] = ...
+    _meta: ClassVar[ModelFormOptions]
 
 def modelform_factory(
     model: type[Model],

django-stubs/forms/utils.pyi

@@ -1,34 +1,61 @@
 from collections import UserList
-from collections.abc import Sequence
+from collections.abc import Mapping, Sequence
 from datetime import datetime
 from typing import Any
 
 from django.core.exceptions import ValidationError
+from django.forms.renderers import BaseRenderer
 from django.utils.safestring import SafeText
 
 def pretty_name(name: str) -> str: ...
 def flatatt(attrs: dict[str, Any]) -> SafeText: ...
 
-class ErrorDict(dict[str, Any]):
+class RenderableMixin:
+    def get_context(self) -> Mapping[str, Any]: ...
+    def render(
+        self,
+        template_name: str | None = ...,
+        context: Mapping[str, Any] | None = ...,
+        renderer: BaseRenderer | None = ...,
+    ) -> SafeText: ...
+
+class RenderableFormMixin(RenderableMixin):
+    def as_p(self) -> SafeText: ...
+    def as_table(self) -> SafeText: ...
+    def as_ul(self) -> SafeText: ...
+    def as_div(self) -> SafeText: ...
+
+class RenderableErrorMixin(RenderableMixin):
+    def as_json(self, escape_html: bool = ...) -> str: ...
+    def as_text(self) -> SafeText: ...
+    def as_ul(self) -> SafeText: ...
+
+class ErrorDict(dict[str, ErrorList], RenderableErrorMixin):
+    template_name: str
+    template_name_text: str
+    template_name_ul: str
+    renderer: BaseRenderer
+    def __init__(
+        self, *args: Any, renderer: BaseRenderer | None = ..., **kwargs: Any
+    ): ...
     def as_data(self) -> dict[str, list[ValidationError]]: ...
     def get_json_data(self, escape_html: bool = ...) -> dict[str, Any]: ...
-    def as_json(self, escape_html: bool = ...) -> str: ...
-    def as_ul(self) -> str: ...
-    def as_text(self) -> str: ...
 
-class ErrorList(UserList[Any]):
+class ErrorList(UserList[ValidationError | str], RenderableErrorMixin):
+    template_name: str
+    template_name_text: str
+    template_name_ul: str
     data: list[ValidationError | str]
-    error_class: str = ...
+    error_class: str
+    renderer: BaseRenderer
     def __init__(
         self,
-        initlist: ErrorList | Sequence[str | Exception] | None = ...,
+        initlist: Sequence[str | Exception] | None = ...,
         error_class: str | None = ...,
+        renderer: BaseRenderer | None = None,
     ) -> None: ...
     def as_data(self) -> list[ValidationError]: ...
     def get_json_data(self, escape_html: bool = ...) -> list[dict[str, str]]: ...
-    def as_json(self, escape_html: bool = ...) -> str: ...
-    def as_ul(self) -> str: ...
-    def as_text(self) -> str: ...
 
 def from_current_timezone(value: datetime) -> datetime: ...
 def to_current_timezone(value: datetime) -> datetime: ...