Add slicing notation to F expressions (#1897)

django-stubs/db/models/expressions.pyi

@@ -1,7 +1,7 @@
 import datetime
 from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
 from decimal import Decimal
-from typing import Any, ClassVar, Generic, Literal, TypeVar
+from typing import Any, ClassVar, Generic, Literal, NoReturn, TypeVar
 
 from django.db.backends.base.base import BaseDatabaseWrapper
 from django.db.models import Q, fields
@@ -132,6 +132,8 @@ class F(_Deconstructible, Combinable):
     name: str
     allowed_default: ClassVar[bool]
     def __init__(self, name: str) -> None: ...
+    def __getitem__(self, subscript: int | slice) -> Sliced: ...
+    def __contains__(self, other: Any) -> NoReturn: ...
     def resolve_expression(
         self,
         query: Any | None = None,
@@ -154,7 +156,18 @@ class F(_Deconstructible, Combinable):
         nulls_first: bool | None = ...,
         nulls_last: bool | None = ...,
     ) -> OrderBy: ...
-    def copy(self) -> F: ...
+    def copy(self) -> Self: ...
+
+class Sliced(F):
+    def __init__(self, obj: F, subscript: int | slice) -> None: ...
+    def resolve_expression(
+        self,
+        query: Any | None = None,
+        allow_joins: bool = True,
+        reuse: set[str] | None = None,
+        summarize: bool = False,
+        for_save: bool = False,
+    ) -> Func: ...
 
 class ResolvedOuterRef(F):
     contains_aggregate: ClassVar[bool]

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

@@ -10,7 +10,7 @@ from django.core import validators  # due to weird mypy.stubtest error
 from django.core.checks import CheckMessage
 from django.db.backends.base.base import BaseDatabaseWrapper
 from django.db.models import Model
-from django.db.models.expressions import Col, Combinable, Expression
+from django.db.models.expressions import Col, Combinable, Expression, Func
 from django.db.models.fields.reverse_related import ForeignObjectRel
 from django.db.models.query_utils import Q, RegisterLookupMixin
 from django.forms import Widget
@@ -234,6 +234,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     def get_attname(self) -> str: ...
     def get_attname_column(self) -> tuple[str, str]: ...
     def value_to_string(self, obj: Model) -> str: ...
+    def slice_expression(self, expression: Expression, start: int, end: int | None) -> Func: ...
 
 class IntegerField(Field[_ST, _GT]):
     _pyi_private_set_type: float | int | str | Combinable

scripts/stubtest/allowlist_todo_django51.txt

@@ -30,8 +30,6 @@ django.contrib.gis.admin.ModelAdmin.log_deletions
 django.contrib.gis.db.backends.mysql.operations.MySQLOperations.collect
 django.contrib.gis.db.models.CharField.slice_expression
 django.contrib.gis.db.models.CheckConstraint.__init__
-django.contrib.gis.db.models.F.__contains__
-django.contrib.gis.db.models.F.__getitem__
 django.contrib.gis.db.models.Field.slice_expression
 django.contrib.gis.db.models.ForeignObjectRel.accessor_name
 django.contrib.gis.db.models.ForeignObjectRel.cache_name
@@ -257,8 +255,6 @@ django.db.migrations.operations.special.SeparateDatabaseAndState.category
 django.db.migrations.serializer.FUNCTION_TYPES
 django.db.models.CharField.slice_expression
 django.db.models.CheckConstraint.__init__
-django.db.models.F.__contains__
-django.db.models.F.__getitem__
 django.db.models.Field.slice_expression
 django.db.models.ForeignObjectRel.accessor_name
 django.db.models.ForeignObjectRel.cache_name
@@ -279,10 +275,7 @@ django.db.models.base.Model.save
 django.db.models.constraints.CheckConstraint.__init__
 django.db.models.expressions.BaseExpression.constraint_validation_compatible
 django.db.models.expressions.BaseExpression.get_expression_for_validation
-django.db.models.expressions.F.__contains__
-django.db.models.expressions.F.__getitem__
 django.db.models.expressions.OrderBy.constraint_validation_compatible
-django.db.models.expressions.Sliced
 django.db.models.expressions.WindowFrame.__init__
 django.db.models.expressions.WindowFrame.get_exclusion
 django.db.models.expressions.WindowFrameExclusion