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"""Private logic for creating pydantic dataclasses."""
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from __future__ import annotations as _annotations
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import copy
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import dataclasses
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import sys
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import warnings
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from collections.abc import Generator
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from contextlib import contextmanager
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from functools import partial
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from typing import TYPE_CHECKING, Any, ClassVar, Protocol, cast
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from pydantic_core import (
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ArgsKwargs,
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SchemaSerializer,
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SchemaValidator,
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core_schema,
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)
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from typing_extensions import TypeAlias, TypeIs
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from ..errors import PydanticUndefinedAnnotation
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from ..fields import FieldInfo
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from ..plugin._schema_validator import PluggableSchemaValidator, create_schema_validator
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from ..warnings import PydanticDeprecatedSince20
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from . import _config, _decorators
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from ._fields import collect_dataclass_fields
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from ._generate_schema import GenerateSchema, InvalidSchemaError
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from ._generics import get_standard_typevars_map
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from ._mock_val_ser import set_dataclass_mocks
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from ._namespace_utils import NsResolver
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from ._signature import generate_pydantic_signature
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from ._utils import LazyClassAttribute
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if TYPE_CHECKING:
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from _typeshed import DataclassInstance as StandardDataclass
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from ..config import ConfigDict
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class PydanticDataclass(StandardDataclass, Protocol):
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"""A protocol containing attributes only available once a class has been decorated as a Pydantic dataclass.
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Attributes:
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__pydantic_config__: Pydantic-specific configuration settings for the dataclass.
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__pydantic_complete__: Whether dataclass building is completed, or if there are still undefined fields.
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__pydantic_core_schema__: The pydantic-core schema used to build the SchemaValidator and SchemaSerializer.
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__pydantic_decorators__: Metadata containing the decorators defined on the dataclass.
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__pydantic_fields__: Metadata about the fields defined on the dataclass.
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__pydantic_serializer__: The pydantic-core SchemaSerializer used to dump instances of the dataclass.
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__pydantic_validator__: The pydantic-core SchemaValidator used to validate instances of the dataclass.
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"""
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__pydantic_config__: ClassVar[ConfigDict]
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__pydantic_complete__: ClassVar[bool]
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__pydantic_core_schema__: ClassVar[core_schema.CoreSchema]
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__pydantic_decorators__: ClassVar[_decorators.DecoratorInfos]
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__pydantic_fields__: ClassVar[dict[str, FieldInfo]]
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__pydantic_serializer__: ClassVar[SchemaSerializer]
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__pydantic_validator__: ClassVar[SchemaValidator | PluggableSchemaValidator]
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@classmethod
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def __pydantic_fields_complete__(cls) -> bool: ...
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def set_dataclass_fields(
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cls: type[StandardDataclass],
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config_wrapper: _config.ConfigWrapper,
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ns_resolver: NsResolver | None = None,
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) -> None:
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"""Collect and set `cls.__pydantic_fields__`.
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Args:
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cls: The class.
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config_wrapper: The config wrapper instance.
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ns_resolver: Namespace resolver to use when getting dataclass annotations.
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"""
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typevars_map = get_standard_typevars_map(cls)
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fields = collect_dataclass_fields(
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cls, ns_resolver=ns_resolver, typevars_map=typevars_map, config_wrapper=config_wrapper
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)
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cls.__pydantic_fields__ = fields # type: ignore
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def complete_dataclass(
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cls: type[Any],
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config_wrapper: _config.ConfigWrapper,
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*,
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raise_errors: bool = True,
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ns_resolver: NsResolver | None = None,
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_force_build: bool = False,
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) -> bool:
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"""Finish building a pydantic dataclass.
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This logic is called on a class which has already been wrapped in `dataclasses.dataclass()`.
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This is somewhat analogous to `pydantic._internal._model_construction.complete_model_class`.
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Args:
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cls: The class.
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config_wrapper: The config wrapper instance.
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raise_errors: Whether to raise errors, defaults to `True`.
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ns_resolver: The namespace resolver instance to use when collecting dataclass fields
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and during schema building.
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_force_build: Whether to force building the dataclass, no matter if
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[`defer_build`][pydantic.config.ConfigDict.defer_build] is set.
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Returns:
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`True` if building a pydantic dataclass is successfully completed, `False` otherwise.
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Raises:
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PydanticUndefinedAnnotation: If `raise_error` is `True` and there is an undefined annotations.
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"""
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original_init = cls.__init__
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# dataclass.__init__ must be defined here so its `__qualname__` can be changed since functions can't be copied,
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# and so that the mock validator is used if building was deferred:
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def __init__(__dataclass_self__: PydanticDataclass, *args: Any, **kwargs: Any) -> None:
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__tracebackhide__ = True
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s = __dataclass_self__
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s.__pydantic_validator__.validate_python(ArgsKwargs(args, kwargs), self_instance=s)
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__init__.__qualname__ = f'{cls.__qualname__}.__init__'
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cls.__init__ = __init__ # type: ignore
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cls.__pydantic_config__ = config_wrapper.config_dict # type: ignore
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set_dataclass_fields(cls, config_wrapper=config_wrapper, ns_resolver=ns_resolver)
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if not _force_build and config_wrapper.defer_build:
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set_dataclass_mocks(cls)
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return False
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if hasattr(cls, '__post_init_post_parse__'):
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warnings.warn(
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'Support for `__post_init_post_parse__` has been dropped, the method will not be called',
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PydanticDeprecatedSince20,
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)
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typevars_map = get_standard_typevars_map(cls)
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gen_schema = GenerateSchema(
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config_wrapper,
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ns_resolver=ns_resolver,
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typevars_map=typevars_map,
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)
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# set __signature__ attr only for the class, but not for its instances
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# (because instances can define `__call__`, and `inspect.signature` shouldn't
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# use the `__signature__` attribute and instead generate from `__call__`).
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cls.__signature__ = LazyClassAttribute(
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'__signature__',
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partial(
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generate_pydantic_signature,
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# It's important that we reference the `original_init` here,
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# as it is the one synthesized by the stdlib `dataclass` module:
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init=original_init,
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fields=cls.__pydantic_fields__, # type: ignore
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validate_by_name=config_wrapper.validate_by_name,
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extra=config_wrapper.extra,
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is_dataclass=True,
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),
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)
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try:
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schema = gen_schema.generate_schema(cls)
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except PydanticUndefinedAnnotation as e:
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if raise_errors:
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raise
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set_dataclass_mocks(cls, f'`{e.name}`')
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return False
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core_config = config_wrapper.core_config(title=cls.__name__)
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try:
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schema = gen_schema.clean_schema(schema)
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except InvalidSchemaError:
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set_dataclass_mocks(cls)
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return False
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# We are about to set all the remaining required properties expected for this cast;
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# __pydantic_decorators__ and __pydantic_fields__ should already be set
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cls = cast('type[PydanticDataclass]', cls)
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cls.__pydantic_core_schema__ = schema
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cls.__pydantic_validator__ = create_schema_validator(
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schema, cls, cls.__module__, cls.__qualname__, 'dataclass', core_config, config_wrapper.plugin_settings
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)
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cls.__pydantic_serializer__ = SchemaSerializer(schema, core_config)
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cls.__pydantic_complete__ = True
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return True
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def is_stdlib_dataclass(cls: type[Any], /) -> TypeIs[type[StandardDataclass]]:
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"""Returns `True` if the class is a stdlib dataclass and *not* a Pydantic dataclass.
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Unlike the stdlib `dataclasses.is_dataclass()` function, this does *not* include subclasses
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of a dataclass that are themselves not dataclasses.
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Args:
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cls: The class.
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Returns:
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`True` if the class is a stdlib dataclass, `False` otherwise.
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"""
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return '__dataclass_fields__' in cls.__dict__ and not hasattr(cls, '__pydantic_validator__')
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def as_dataclass_field(pydantic_field: FieldInfo) -> dataclasses.Field[Any]:
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field_args: dict[str, Any] = {'default': pydantic_field}
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# Needed because if `doc` is set, the dataclass slots will be a dict (field name -> doc) instead of a tuple:
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if sys.version_info >= (3, 14) and pydantic_field.description is not None:
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field_args['doc'] = pydantic_field.description
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# Needed as the stdlib dataclass module processes kw_only in a specific way during class construction:
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if sys.version_info >= (3, 10) and pydantic_field.kw_only:
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field_args['kw_only'] = True
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# Needed as the stdlib dataclass modules generates `__repr__()` during class construction:
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if pydantic_field.repr is not True:
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field_args['repr'] = pydantic_field.repr
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return dataclasses.field(**field_args)
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DcFields: TypeAlias = dict[str, dataclasses.Field[Any]]
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@contextmanager
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def patch_base_fields(cls: type[Any]) -> Generator[None]:
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"""Temporarily patch the stdlib dataclasses bases of `cls` if the Pydantic `Field()` function is used.
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When creating a Pydantic dataclass, it is possible to inherit from stdlib dataclasses, where
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the Pydantic `Field()` function is used. To create this Pydantic dataclass, we first apply
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the stdlib `@dataclass` decorator on it. During the construction of the stdlib dataclass,
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the `kw_only` and `repr` field arguments need to be understood by the stdlib *during* the
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dataclass construction. To do so, we temporarily patch the fields dictionary of the affected
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bases.
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For instance, with the following example:
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```python {test="skip" lint="skip"}
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import dataclasses as stdlib_dc
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import pydantic
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import pydantic.dataclasses as pydantic_dc
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@stdlib_dc.dataclass
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class A:
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a: int = pydantic.Field(repr=False)
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# Notice that the `repr` attribute of the dataclass field is `True`:
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A.__dataclass_fields__['a']
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#> dataclass.Field(default=FieldInfo(repr=False), repr=True, ...)
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@pydantic_dc.dataclass
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class B(A):
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b: int = pydantic.Field(repr=False)
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```
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When passing `B` to the stdlib `@dataclass` decorator, it will look for fields in the parent classes
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and reuse them directly. When this context manager is active, `A` will be temporarily patched to be
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equivalent to:
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```python {test="skip" lint="skip"}
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@stdlib_dc.dataclass
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class A:
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a: int = stdlib_dc.field(default=Field(repr=False), repr=False)
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```
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!!! note
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This is only applied to the bases of `cls`, and not `cls` itself. The reason is that the Pydantic
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dataclass decorator "owns" `cls` (in the previous example, `B`). As such, we instead modify the fields
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directly (in the previous example, we simply do `setattr(B, 'b', as_dataclass_field(pydantic_field))`).
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!!! note
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This approach is far from ideal, and can probably be the source of unwanted side effects/race conditions.
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The previous implemented approach was mutating the `__annotations__` dict of `cls`, which is no longer a
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safe operation in Python 3.14+, and resulted in unexpected behavior with field ordering anyway.
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"""
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# A list of two-tuples, the first element being a reference to the
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# dataclass fields dictionary, the second element being a mapping between
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# the field names that were modified, and their original `Field`:
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original_fields_list: list[tuple[DcFields, DcFields]] = []
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for base in cls.__mro__[1:]:
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dc_fields: dict[str, dataclasses.Field[Any]] = base.__dict__.get('__dataclass_fields__', {})
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dc_fields_with_pydantic_field_defaults = {
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field_name: field
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for field_name, field in dc_fields.items()
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if isinstance(field.default, FieldInfo)
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# Only do the patching if one of the affected attributes is set:
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and (field.default.description is not None or field.default.kw_only or field.default.repr is not True)
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}
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if dc_fields_with_pydantic_field_defaults:
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original_fields_list.append((dc_fields, dc_fields_with_pydantic_field_defaults))
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for field_name, field in dc_fields_with_pydantic_field_defaults.items():
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default = cast(FieldInfo, field.default)
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# `dataclasses.Field` isn't documented as working with `copy.copy()`.
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# It is a class with `__slots__`, so should work (and we hope for the best):
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new_dc_field = copy.copy(field)
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# For base fields, no need to set `doc` from `FieldInfo.description`, this is only relevant
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# for the class under construction and handled in `as_dataclass_field()`.
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if sys.version_info >= (3, 10) and default.kw_only:
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new_dc_field.kw_only = True
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if default.repr is not True:
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new_dc_field.repr = default.repr
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dc_fields[field_name] = new_dc_field
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try:
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yield
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finally:
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for fields, original_fields in original_fields_list:
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for field_name, original_field in original_fields.items():
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fields[field_name] = original_field
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