Several stub for django.db.models.base.Model are missing

[AndreyMZ]

Bug report

What's wrong

Steps to reproduce

The following code produces the following warning.

from django.db import models

class MyModel(models.Model):
	foo = models.CharField(max_length=255)
	bar = models.CharField(max_length=255)
	
	def clean(self):
		raise self.unique_error_message(MyModel, ('foo', 'bar'))

Unresolved attribute reference 'unique_error_message' for class 'MyModel'

Root cause

No django.db.models.base.Model.unique_error_message method in the stub.

django-stubs/django-stubs/db/models/base.pyi

Lines 11 to 44 in 8402e7c

	class Model(metaclass=ModelBase):
	class DoesNotExist(Exception): ...
	class MultipleObjectsReturned(Exception): ...
	class Meta: ...
	_default_manager: Manager[Model]
	_meta: Options[Any]
	objects: Manager[Any]
	pk: Any = ...
	def __init__(self: _Self, *args, **kwargs) -> None: ...
	def delete(self, using: Any = ..., keep_parents: bool = ...) -> Tuple[int, Dict[str, int]]: ...
	def full_clean(self, exclude: Optional[Collection[str]] = ..., validate_unique: bool = ...) -> None: ...
	def clean(self) -> None: ...
	def clean_fields(self, exclude: Optional[Collection[str]] = ...) -> None: ...
	def validate_unique(self, exclude: Optional[Collection[str]] = ...) -> None: ...
	def save(
	self,
	force_insert: bool = ...,
	force_update: bool = ...,
	using: Optional[str] = ...,
	update_fields: Optional[Union[Sequence[str], str]] = ...,
	) -> None: ...
	def save_base(
	self,
	raw: bool = ...,
	force_insert: bool = ...,
	force_update: bool = ...,
	using: Optional[str] = ...,
	update_fields: Optional[Union[Sequence[str], str]] = ...,
	): ...
	def refresh_from_db(self: _Self, using: Optional[str] = ..., fields: Optional[List[str]] = ...) -> _Self: ...
	def get_deferred_fields(self) -> Set[str]: ...
	@classmethod
	def check(cls, **kwargs: Any) -> List[CheckMessage]: ...
	def __getstate__(self) -> dict: ...

How is that should be

django.db.models.base.Model.unique_error_message and all other methods of django.db.models.base.Model class must be in the stub:

from typing import Callable, Type
from django.core.exceptions import ValidationError

# <...>

class Model(metaclass=ModelBase):
	# <...>
	def unique_error_message(self, model_class: Type[_Self], unique_check: Collection[Union[Callable, str]]) -> ValidationError: ... 
	# <...>

System information

• OS: Windows 10
• python version: 3.6.8
• django version: 2.2.6
• mypy version: -
• PyCharm version: 2019.2.3 (Community Edition)
• django-stubs version: 1.2.0

[sobolevn]

@AndreyMZ thanks a lot! Can you please send a PR with the fix?

[AndreyMZ]

I have sent a PR with the stub for django.db.models.base.Model.unique_error_message.

But I cannot add stubs for other methods (listed below), because I do not know correct type hints.
Maybe for a start it's worth adding stubs with Any type hint, isn't it?

Methods of django.db.models.base.Model with no stub:

• __init__
• from_db
• __repr__
• __str__
• __eq__
• __hash__
• __reduce__
• __getstate__
• __setstate__
• _get_pk_val
• _set_pk_val
• get_deferred_fields
• refresh_from_db
• serializable_value
• save
• save_base
• _save_parents
• _save_table
• _do_update
• _do_insert
• delete
• _get_FIELD_display
• _get_next_or_previous_by_FIELD
• _get_next_or_previous_in_order
• prepare_database_save
• clean
• validate_unique
• _get_unique_checks
• _perform_unique_checks
• _perform_date_checks
• date_error_message
• unique_error_message
• full_clean
• clean_fields
• check
• _check_swappable
• _check_model
• _check_managers
• _check_fields
• _check_m2m_through_same_relationship
• _check_id_field
• _check_field_name_clashes
• _check_column_name_clashes
• _check_model_name_db_lookup_clashes
• _check_property_name_related_field_accessor_clashes
• _check_single_primary_key
• _check_index_together
• _check_unique_together
• _check_indexes
• _check_local_fields
• _check_ordering
• _check_long_column_names
• _check_constraints

[sobolevn]

I will rename this issue and merge the PR. Later we will return to this. Ok?

[adamchainz]

Most of the remaining attributes are private (start with an underscore). We only add private attributes when there’s a known real-world use case: https://github.com/typeddjango/django-stubs/blob/master/CONTRIBUTING.md#private-attributes . Many probably never need overriding, such as the _check* methods.

The non-private attributes in the list seem to have been added: from_db, serializable_value, prepare_database_save, date_error_message.

So I’ll close this issue now - other attributes can be raised in individual issues or straight up PRs.