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