This is a regular dict at runtime (#2604)

Author: UnknownPlatypus

django-stubs/forms/forms.pyi

@@ -1,4 +1,4 @@
-from collections.abc import Iterable, Iterator, Mapping
+from collections.abc import Iterable, Iterator, MutableMapping
 from typing import Any, ClassVar
 
 from django.core.exceptions import ValidationError
@@ -19,7 +19,7 @@ class BaseForm(RenderableFormMixin):
     data: _DataT
     files: _FilesT
     auto_id: bool | str
-    initial: Mapping[str, Any]
+    initial: MutableMapping[str, Any]
     error_class: type[ErrorList]
     prefix: str | None
     label_suffix: str
@@ -38,7 +38,7 @@ class BaseForm(RenderableFormMixin):
         files: _FilesT | None = None,
         auto_id: bool | str = "id_%s",
         prefix: str | None = None,
-        initial: Mapping[str, Any] | None = None,
+        initial: MutableMapping[str, Any] | None = None,
         error_class: type[ErrorList] = ...,
         label_suffix: str | None = None,
         empty_permitted: bool = False,

django-stubs/forms/models.pyi

@@ -1,4 +1,4 @@
-from collections.abc import Callable, Collection, Container, Iterator, Mapping, Sequence
+from collections.abc import Callable, Collection, Container, Iterator, Mapping, MutableMapping, Sequence
 from typing import Any, ClassVar, Generic, Literal, TypeAlias, TypeVar, overload
 from uuid import UUID
 
@@ -76,7 +76,7 @@ class BaseModelForm(Generic[_M], BaseForm):
         files: _FilesT | None = None,
         auto_id: bool | str = "id_%s",
         prefix: str | None = None,
-        initial: Mapping[str, Any] | None = None,
+        initial: MutableMapping[str, Any] | None = None,
         error_class: type[ErrorList] = ...,
         label_suffix: str | None = None,
         empty_permitted: bool = False,