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"""
The main purpose is to enhance stdlib dataclasses by adding validation
A pydantic dataclass can be generated from scratch or from a stdlib one.
Behind the scene, a pydantic dataclass is just like a regular one on which we attach
a `BaseModel` and magic methods to trigger the validation of the data.
`__init__` and `__post_init__` are hence overridden and have extra logic to be
able to validate input data.
When a pydantic dataclass is generated from scratch, it's just a plain dataclass
with validation triggered at initialization
The tricky part if for stdlib dataclasses that are converted after into pydantic ones e.g.
```py
@dataclasses.dataclass
class M:
x: int
ValidatedM = pydantic.dataclasses.dataclass(M)
```
We indeed still want to support equality, hashing, repr, ... as if it was the stdlib one!
```py
assert isinstance(ValidatedM(x=1), M)
assert ValidatedM(x=1) == M(x=1)
```
This means we **don't want to create a new dataclass that inherits from it**
The trick is to create a wrapper around `M` that will act as a proxy to trigger
validation without altering default `M` behaviour.
"""
import copy
import dataclasses
import sys
from contextlib import contextmanager
from functools import wraps
try:
from functools import cached_property
except ImportError:
# cached_property available only for python3.8+
pass
from typing import TYPE_CHECKING, Any, Callable, ClassVar, Dict, Generator, Optional, Type, TypeVar, Union, overload
from typing_extensions import dataclass_transform
from .class_validators import gather_all_validators
from .config import BaseConfig, ConfigDict, Extra, get_config
from .error_wrappers import ValidationError
from .errors import DataclassTypeError
from .fields import Field, FieldInfo, Required, Undefined
from .main import create_model, validate_model
from .utils import ClassAttribute
if TYPE_CHECKING:
from .main import BaseModel
from .typing import CallableGenerator, NoArgAnyCallable
DataclassT = TypeVar('DataclassT', bound='Dataclass')
DataclassClassOrWrapper = Union[Type['Dataclass'], 'DataclassProxy']
class Dataclass:
# stdlib attributes
__dataclass_fields__: ClassVar[Dict[str, Any]]
__dataclass_params__: ClassVar[Any] # in reality `dataclasses._DataclassParams`
__post_init__: ClassVar[Callable[..., None]]
# Added by pydantic
__pydantic_run_validation__: ClassVar[bool]
__post_init_post_parse__: ClassVar[Callable[..., None]]
__pydantic_initialised__: ClassVar[bool]
__pydantic_model__: ClassVar[Type[BaseModel]]
__pydantic_validate_values__: ClassVar[Callable[['Dataclass'], None]]
__pydantic_has_field_info_default__: ClassVar[bool] # whether a `pydantic.Field` is used as default value
def __init__(self, *args: object, **kwargs: object) -> None:
pass
@classmethod
def __get_validators__(cls: Type['Dataclass']) -> 'CallableGenerator':
pass
@classmethod
def __validate__(cls: Type['DataclassT'], v: Any) -> 'DataclassT':
pass
__all__ = [
'dataclass',
'set_validation',
'create_pydantic_model_from_dataclass',
'is_builtin_dataclass',
'make_dataclass_validator',
]
_T = TypeVar('_T')
if sys.version_info >= (3, 10):
@dataclass_transform(field_specifiers=(dataclasses.field, Field))
@overload
def dataclass(
*,
init: bool = True,
repr: bool = True,
eq: bool = True,
order: bool = False,
unsafe_hash: bool = False,
frozen: bool = False,
config: Union[ConfigDict, Type[object], None] = None,
validate_on_init: Optional[bool] = None,
use_proxy: Optional[bool] = None,
kw_only: bool = ...,
) -> Callable[[Type[_T]], 'DataclassClassOrWrapper']:
...
@dataclass_transform(field_specifiers=(dataclasses.field, Field))
@overload
def dataclass(
_cls: Type[_T],
*,
init: bool = True,
repr: bool = True,
eq: bool = True,
order: bool = False,
unsafe_hash: bool = False,
frozen: bool = False,
config: Union[ConfigDict, Type[object], None] = None,
validate_on_init: Optional[bool] = None,
use_proxy: Optional[bool] = None,
kw_only: bool = ...,
) -> 'DataclassClassOrWrapper':
...
else:
@dataclass_transform(field_specifiers=(dataclasses.field, Field))
@overload
def dataclass(
*,
init: bool = True,
repr: bool = True,
eq: bool = True,
order: bool = False,
unsafe_hash: bool = False,
frozen: bool = False,
config: Union[ConfigDict, Type[object], None] = None,
validate_on_init: Optional[bool] = None,
use_proxy: Optional[bool] = None,
) -> Callable[[Type[_T]], 'DataclassClassOrWrapper']:
...
@dataclass_transform(field_specifiers=(dataclasses.field, Field))
@overload
def dataclass(
_cls: Type[_T],
*,
init: bool = True,
repr: bool = True,
eq: bool = True,
order: bool = False,
unsafe_hash: bool = False,
frozen: bool = False,
config: Union[ConfigDict, Type[object], None] = None,
validate_on_init: Optional[bool] = None,
use_proxy: Optional[bool] = None,
) -> 'DataclassClassOrWrapper':
...
@dataclass_transform(field_specifiers=(dataclasses.field, Field))
def dataclass(
_cls: Optional[Type[_T]] = None,
*,
init: bool = True,
repr: bool = True,
eq: bool = True,
order: bool = False,
unsafe_hash: bool = False,
frozen: bool = False,
config: Union[ConfigDict, Type[object], None] = None,
validate_on_init: Optional[bool] = None,
use_proxy: Optional[bool] = None,
kw_only: bool = False,
) -> Union[Callable[[Type[_T]], 'DataclassClassOrWrapper'], 'DataclassClassOrWrapper']:
"""
Like the python standard lib dataclasses but with type validation.
The result is either a pydantic dataclass that will validate input data
or a wrapper that will trigger validation around a stdlib dataclass
to avoid modifying it directly
"""
the_config = get_config(config)
def wrap(cls: Type[Any]) -> 'DataclassClassOrWrapper':
should_use_proxy = (
use_proxy
if use_proxy is not None
else (
is_builtin_dataclass(cls)
and (cls.__bases__[0] is object or set(dir(cls)) == set(dir(cls.__bases__[0])))
)
)
if should_use_proxy:
dc_cls_doc = ''
dc_cls = DataclassProxy(cls)
default_validate_on_init = False
else:
dc_cls_doc = cls.__doc__ or '' # needs to be done before generating dataclass
if sys.version_info >= (3, 10):
dc_cls = dataclasses.dataclass(
cls,
init=init,
repr=repr,
eq=eq,
order=order,
unsafe_hash=unsafe_hash,
frozen=frozen,
kw_only=kw_only,
)
else:
dc_cls = dataclasses.dataclass( # type: ignore
cls, init=init, repr=repr, eq=eq, order=order, unsafe_hash=unsafe_hash, frozen=frozen
)
default_validate_on_init = True
should_validate_on_init = default_validate_on_init if validate_on_init is None else validate_on_init
_add_pydantic_validation_attributes(cls, the_config, should_validate_on_init, dc_cls_doc)
dc_cls.__pydantic_model__.__try_update_forward_refs__(**{cls.__name__: cls})
return dc_cls
if _cls is None:
return wrap
return wrap(_cls)
@contextmanager
def set_validation(cls: Type['DataclassT'], value: bool) -> Generator[Type['DataclassT'], None, None]:
original_run_validation = cls.__pydantic_run_validation__
try:
cls.__pydantic_run_validation__ = value
yield cls
finally:
cls.__pydantic_run_validation__ = original_run_validation
class DataclassProxy:
__slots__ = '__dataclass__'
def __init__(self, dc_cls: Type['Dataclass']) -> None:
object.__setattr__(self, '__dataclass__', dc_cls)
def __call__(self, *args: Any, **kwargs: Any) -> Any:
with set_validation(self.__dataclass__, True):
return self.__dataclass__(*args, **kwargs)
def __getattr__(self, name: str) -> Any:
return getattr(self.__dataclass__, name)
def __setattr__(self, __name: str, __value: Any) -> None:
return setattr(self.__dataclass__, __name, __value)
def __instancecheck__(self, instance: Any) -> bool:
return isinstance(instance, self.__dataclass__)
def __copy__(self) -> 'DataclassProxy':
return DataclassProxy(copy.copy(self.__dataclass__))
def __deepcopy__(self, memo: Any) -> 'DataclassProxy':
return DataclassProxy(copy.deepcopy(self.__dataclass__, memo))
def _add_pydantic_validation_attributes( # noqa: C901 (ignore complexity)
dc_cls: Type['Dataclass'],
config: Type[BaseConfig],
validate_on_init: bool,
dc_cls_doc: str,
) -> None:
"""
We need to replace the right method. If no `__post_init__` has been set in the stdlib dataclass
it won't even exist (code is generated on the fly by `dataclasses`)
By default, we run validation after `__init__` or `__post_init__` if defined
"""
init = dc_cls.__init__
@wraps(init)
def handle_extra_init(self: 'Dataclass', *args: Any, **kwargs: Any) -> None:
if config.extra == Extra.ignore:
init(self, *args, **{k: v for k, v in kwargs.items() if k in self.__dataclass_fields__})
elif config.extra == Extra.allow:
for k, v in kwargs.items():
self.__dict__.setdefault(k, v)
init(self, *args, **{k: v for k, v in kwargs.items() if k in self.__dataclass_fields__})
else:
init(self, *args, **kwargs)
if hasattr(dc_cls, '__post_init__'):
try:
post_init = dc_cls.__post_init__.__wrapped__ # type: ignore[attr-defined]
except AttributeError:
post_init = dc_cls.__post_init__
@wraps(post_init)
def new_post_init(self: 'Dataclass', *args: Any, **kwargs: Any) -> None:
if config.post_init_call == 'before_validation':
post_init(self, *args, **kwargs)
if self.__class__.__pydantic_run_validation__:
self.__pydantic_validate_values__()
if hasattr(self, '__post_init_post_parse__'):
self.__post_init_post_parse__(*args, **kwargs)
if config.post_init_call == 'after_validation':
post_init(self, *args, **kwargs)
setattr(dc_cls, '__init__', handle_extra_init)
setattr(dc_cls, '__post_init__', new_post_init)
else:
@wraps(init)
def new_init(self: 'Dataclass', *args: Any, **kwargs: Any) -> None:
handle_extra_init(self, *args, **kwargs)
if self.__class__.__pydantic_run_validation__:
self.__pydantic_validate_values__()
if hasattr(self, '__post_init_post_parse__'):
# We need to find again the initvars. To do that we use `__dataclass_fields__` instead of
# public method `dataclasses.fields`
# get all initvars and their default values
initvars_and_values: Dict[str, Any] = {}
for i, f in enumerate(self.__class__.__dataclass_fields__.values()):
if f._field_type is dataclasses._FIELD_INITVAR: # type: ignore[attr-defined]
try:
# set arg value by default
initvars_and_values[f.name] = args[i]
except IndexError:
initvars_and_values[f.name] = kwargs.get(f.name, f.default)
self.__post_init_post_parse__(**initvars_and_values)
setattr(dc_cls, '__init__', new_init)
setattr(dc_cls, '__pydantic_run_validation__', ClassAttribute('__pydantic_run_validation__', validate_on_init))
setattr(dc_cls, '__pydantic_initialised__', False)
setattr(dc_cls, '__pydantic_model__', create_pydantic_model_from_dataclass(dc_cls, config, dc_cls_doc))
setattr(dc_cls, '__pydantic_validate_values__', _dataclass_validate_values)
setattr(dc_cls, '__validate__', classmethod(_validate_dataclass))
setattr(dc_cls, '__get_validators__', classmethod(_get_validators))
if dc_cls.__pydantic_model__.__config__.validate_assignment and not dc_cls.__dataclass_params__.frozen:
setattr(dc_cls, '__setattr__', _dataclass_validate_assignment_setattr)
def _get_validators(cls: 'DataclassClassOrWrapper') -> 'CallableGenerator':
yield cls.__validate__
def _validate_dataclass(cls: Type['DataclassT'], v: Any) -> 'DataclassT':
with set_validation(cls, True):
if isinstance(v, cls):
v.__pydantic_validate_values__()
return v
elif isinstance(v, (list, tuple)):
return cls(*v)
elif isinstance(v, dict):
return cls(**v)
else:
raise DataclassTypeError(class_name=cls.__name__)
def create_pydantic_model_from_dataclass(
dc_cls: Type['Dataclass'],
config: Type[Any] = BaseConfig,
dc_cls_doc: Optional[str] = None,
) -> Type['BaseModel']:
field_definitions: Dict[str, Any] = {}
for field in dataclasses.fields(dc_cls):
default: Any = Undefined
default_factory: Optional['NoArgAnyCallable'] = None
field_info: FieldInfo
if field.default is not dataclasses.MISSING:
default = field.default
elif field.default_factory is not dataclasses.MISSING:
default_factory = field.default_factory
else:
default = Required
if isinstance(default, FieldInfo):
field_info = default
dc_cls.__pydantic_has_field_info_default__ = True
else:
field_info = Field(default=default, default_factory=default_factory, **field.metadata)
field_definitions[field.name] = (field.type, field_info)
validators = gather_all_validators(dc_cls)
model: Type['BaseModel'] = create_model(
dc_cls.__name__,
__config__=config,
__module__=dc_cls.__module__,
__validators__=validators,
__cls_kwargs__={'__resolve_forward_refs__': False},
**field_definitions,
)
model.__doc__ = dc_cls_doc if dc_cls_doc is not None else dc_cls.__doc__ or ''
return model
if sys.version_info >= (3, 8):
def _is_field_cached_property(obj: 'Dataclass', k: str) -> bool:
return isinstance(getattr(type(obj), k, None), cached_property)
else:
def _is_field_cached_property(obj: 'Dataclass', k: str) -> bool:
return False
def _dataclass_validate_values(self: 'Dataclass') -> None:
# validation errors can occur if this function is called twice on an already initialised dataclass.
# for example if Extra.forbid is enabled, it would consider __pydantic_initialised__ an invalid extra property
if getattr(self, '__pydantic_initialised__'):
return
if getattr(self, '__pydantic_has_field_info_default__', False):
# We need to remove `FieldInfo` values since they are not valid as input
# It's ok to do that because they are obviously the default values!
input_data = {
k: v
for k, v in self.__dict__.items()
if not (isinstance(v, FieldInfo) or _is_field_cached_property(self, k))
}
else:
input_data = {k: v for k, v in self.__dict__.items() if not _is_field_cached_property(self, k)}
d, _, validation_error = validate_model(self.__pydantic_model__, input_data, cls=self.__class__)
if validation_error:
raise validation_error
self.__dict__.update(d)
object.__setattr__(self, '__pydantic_initialised__', True)
def _dataclass_validate_assignment_setattr(self: 'Dataclass', name: str, value: Any) -> None:
if self.__pydantic_initialised__:
d = dict(self.__dict__)
d.pop(name, None)
known_field = self.__pydantic_model__.__fields__.get(name, None)
if known_field:
value, error_ = known_field.validate(value, d, loc=name, cls=self.__class__)
if error_:
raise ValidationError([error_], self.__class__)
object.__setattr__(self, name, value)
def is_builtin_dataclass(_cls: Type[Any]) -> bool:
"""
Whether a class is a stdlib dataclass
(useful to discriminated a pydantic dataclass that is actually a wrapper around a stdlib dataclass)
we check that
- `_cls` is a dataclass
- `_cls` is not a processed pydantic dataclass (with a basemodel attached)
- `_cls` is not a pydantic dataclass inheriting directly from a stdlib dataclass
e.g.
```
@dataclasses.dataclass
class A:
x: int
@pydantic.dataclasses.dataclass
class B(A):
y: int
```
In this case, when we first check `B`, we make an extra check and look at the annotations ('y'),
which won't be a superset of all the dataclass fields (only the stdlib fields i.e. 'x')
"""
return (
dataclasses.is_dataclass(_cls)
and not hasattr(_cls, '__pydantic_model__')
and set(_cls.__dataclass_fields__).issuperset(set(getattr(_cls, '__annotations__', {})))
)
def make_dataclass_validator(dc_cls: Type['Dataclass'], config: Type[BaseConfig]) -> 'CallableGenerator':
"""
Create a pydantic.dataclass from a builtin dataclass to add type validation
and yield the validators
It retrieves the parameters of the dataclass and forwards them to the newly created dataclass
"""
yield from _get_validators(dataclass(dc_cls, config=config, use_proxy=True))
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