add support for typechecking of filter/get/exclude arguments (#183)

* add support for typechecking of filter/get/exclude arguments

* linting

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

@@ -43,6 +43,7 @@ _GT = TypeVar("_GT")
 class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     _pyi_private_set_type: Any
     _pyi_private_get_type: Any
+    _pyi_lookup_exact_type: Any
 
     widget: Widget
     help_text: str
@@ -131,6 +132,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
 class IntegerField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[float, int, str, Combinable]
     _pyi_private_get_type: int
+    _pyi_lookup_exact_type: int
 
 class PositiveIntegerRelDbTypeMixin:
     def rel_db_type(self, connection: Any): ...
@@ -143,10 +145,12 @@ class BigIntegerField(IntegerField[_ST, _GT]): ...
 class FloatField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[float, int, str, Combinable]
     _pyi_private_get_type: float
+    _pyi_lookup_exact_type: float
 
 class DecimalField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, float, decimal.Decimal, Combinable]
     _pyi_private_get_type: decimal.Decimal
+    _pyi_lookup_exact_type: Union[str, decimal.Decimal]
     # attributes
     max_digits: int = ...
     decimal_places: int = ...
@@ -176,10 +180,13 @@ class DecimalField(Field[_ST, _GT]):
 class AutoField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[Combinable, int, str]
     _pyi_private_get_type: int
+    _pyi_lookup_exact_type: int
 
 class CharField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, int, Combinable]
     _pyi_private_get_type: str
+    # objects are converted to string before comparison
+    _pyi_lookup_exact_type: Any
     def __init__(
         self,
         verbose_name: Optional[Union[str, bytes]] = ...,
@@ -238,14 +245,18 @@ class URLField(CharField[_ST, _GT]): ...
 class TextField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, Combinable]
     _pyi_private_get_type: str
+    # objects are converted to string before comparison
+    _pyi_lookup_exact_type: Any
 
 class BooleanField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[bool, Combinable]
     _pyi_private_get_type: bool
+    _pyi_lookup_exact_type: bool
 
 class NullBooleanField(Field[_ST, _GT]):
     _pyi_private_set_type: Optional[Union[bool, Combinable]]
     _pyi_private_get_type: Optional[bool]
+    _pyi_lookup_exact_type: Optional[bool]
 
 class IPAddressField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, Combinable]
@@ -286,6 +297,7 @@ class DateTimeCheckMixin: ...
 class DateField(DateTimeCheckMixin, Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, date, Combinable]
     _pyi_private_get_type: date
+    _pyi_lookup_exact_type: Union[str, date]
     def __init__(
         self,
         verbose_name: Optional[Union[str, bytes]] = ...,
@@ -338,6 +350,7 @@ class TimeField(DateTimeCheckMixin, Field[_ST, _GT]):
 
 class DateTimeField(DateField[_ST, _GT]):
     _pyi_private_get_type: datetime
+    _pyi_lookup_exact_type: Union[str, datetime]
 
 class UUIDField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[str, uuid.UUID]

django-stubs/db/models/lookups.pyi

@@ -1,5 +1,5 @@
 from datetime import datetime
-from typing import Any, Iterable, List, Mapping, Optional, Tuple, Type, Union
+from typing import Any, Iterable, List, Optional, Tuple, Type, Union, Mapping, TypeVar, Generic
 
 from django.db.backends.sqlite3.base import DatabaseWrapper
 from django.db.models.expressions import Expression, Func
@@ -10,7 +10,9 @@ from django.utils.safestring import SafeText
 
 from django.db.models.fields import TextField, related_lookups
 
-class Lookup:
+_T = TypeVar("_T")
+
+class Lookup(Generic[_T]):
     lookup_name: str = ...
     prepare_rhs: bool = ...
     can_use_none_as_rhs: bool = ...
@@ -47,7 +49,7 @@ class Transform(RegisterLookupMixin, Func):
     def lhs(self) -> Expression: ...
     def get_bilateral_transforms(self) -> List[Type[Transform]]: ...
 
-class BuiltinLookup(Lookup):
+class BuiltinLookup(Lookup[_T]):
     def get_rhs_op(self, connection: DatabaseWrapper, rhs: str) -> str: ...
 
 class FieldGetDbPrepValueMixin:
@@ -62,21 +64,21 @@ class FieldGetDbPrepValueIterableMixin(FieldGetDbPrepValueMixin):
 class Exact(FieldGetDbPrepValueMixin, BuiltinLookup): ...
 class IExact(BuiltinLookup): ...
 class GreaterThan(FieldGetDbPrepValueMixin, BuiltinLookup): ...
-class GreaterThanOrEqual(FieldGetDbPrepValueMixin, BuiltinLookup): ...
-class LessThan(FieldGetDbPrepValueMixin, BuiltinLookup): ...
+class GreaterThanOrEqual(FieldGetDbPrepValueMixin, BuiltinLookup[_T]): ...
+class LessThan(FieldGetDbPrepValueMixin, BuiltinLookup[_T]): ...
 class LessThanOrEqual(FieldGetDbPrepValueMixin, BuiltinLookup): ...
 
 class IntegerFieldFloatRounding:
     rhs: Any = ...
     def get_prep_lookup(self) -> Any: ...
 
-class IntegerGreaterThanOrEqual(IntegerFieldFloatRounding, GreaterThanOrEqual): ...
-class IntegerLessThan(IntegerFieldFloatRounding, LessThan): ...
+class IntegerGreaterThanOrEqual(IntegerFieldFloatRounding, GreaterThanOrEqual[Union[int, float]]): ...
+class IntegerLessThan(IntegerFieldFloatRounding, LessThan[Union[int, float]]): ...
 
 class In(FieldGetDbPrepValueIterableMixin, BuiltinLookup):
     def split_parameter_list_as_sql(self, compiler: Any, connection: Any): ...
 
-class PatternLookup(BuiltinLookup):
+class PatternLookup(BuiltinLookup[str]):
     param_pattern: str = ...
 
 class Contains(PatternLookup): ...
@@ -86,8 +88,8 @@ class IStartsWith(StartsWith): ...
 class EndsWith(PatternLookup): ...
 class IEndsWith(EndsWith): ...
 class Range(FieldGetDbPrepValueIterableMixin, BuiltinLookup): ...
-class IsNull(BuiltinLookup): ...
-class Regex(BuiltinLookup): ...
+class IsNull(BuiltinLookup[bool]): ...
+class Regex(BuiltinLookup[str]): ...
 class IRegex(Regex): ...
 
 class YearLookup(Lookup):