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from __future__ import annotations
import dataclasses
from inspect import Parameter, Signature, signature
from typing import TYPE_CHECKING, Any, Callable
from pydantic_core import PydanticUndefined
from ._utils import is_valid_identifier
if TYPE_CHECKING:
from ..config import ExtraValues
from ..fields import FieldInfo
# Copied over from stdlib dataclasses
class _HAS_DEFAULT_FACTORY_CLASS:
def __repr__(self):
return '<factory>'
_HAS_DEFAULT_FACTORY = _HAS_DEFAULT_FACTORY_CLASS()
def _field_name_for_signature(field_name: str, field_info: FieldInfo) -> str:
"""Extract the correct name to use for the field when generating a signature.
Assuming the field has a valid alias, this will return the alias. Otherwise, it will return the field name.
First priority is given to the alias, then the validation_alias, then the field name.
Args:
field_name: The name of the field
field_info: The corresponding FieldInfo object.
Returns:
The correct name to use when generating a signature.
"""
if isinstance(field_info.alias, str) and is_valid_identifier(field_info.alias):
return field_info.alias
if isinstance(field_info.validation_alias, str) and is_valid_identifier(field_info.validation_alias):
return field_info.validation_alias
return field_name
def _process_param_defaults(param: Parameter) -> Parameter:
"""Modify the signature for a parameter in a dataclass where the default value is a FieldInfo instance.
Args:
param (Parameter): The parameter
Returns:
Parameter: The custom processed parameter
"""
from ..fields import FieldInfo
param_default = param.default
if isinstance(param_default, FieldInfo):
annotation = param.annotation
# Replace the annotation if appropriate
# inspect does "clever" things to show annotations as strings because we have
# `from __future__ import annotations` in main, we don't want that
if annotation == 'Any':
annotation = Any
# Replace the field default
default = param_default.default
if default is PydanticUndefined:
if param_default.default_factory is PydanticUndefined:
default = Signature.empty
else:
# this is used by dataclasses to indicate a factory exists:
default = dataclasses._HAS_DEFAULT_FACTORY # type: ignore
return param.replace(
annotation=annotation, name=_field_name_for_signature(param.name, param_default), default=default
)
return param
def _generate_signature_parameters( # noqa: C901 (ignore complexity, could use a refactor)
init: Callable[..., None],
fields: dict[str, FieldInfo],
populate_by_name: bool,
extra: ExtraValues | None,
) -> dict[str, Parameter]:
"""Generate a mapping of parameter names to Parameter objects for a pydantic BaseModel or dataclass."""
from itertools import islice
present_params = signature(init).parameters.values()
merged_params: dict[str, Parameter] = {}
var_kw = None
use_var_kw = False
for param in islice(present_params, 1, None): # skip self arg
# inspect does "clever" things to show annotations as strings because we have
# `from __future__ import annotations` in main, we don't want that
if fields.get(param.name):
# exclude params with init=False
if getattr(fields[param.name], 'init', True) is False:
continue
param = param.replace(name=_field_name_for_signature(param.name, fields[param.name]))
if param.annotation == 'Any':
param = param.replace(annotation=Any)
if param.kind is param.VAR_KEYWORD:
var_kw = param
continue
merged_params[param.name] = param
if var_kw: # if custom init has no var_kw, fields which are not declared in it cannot be passed through
allow_names = populate_by_name
for field_name, field in fields.items():
# when alias is a str it should be used for signature generation
param_name = _field_name_for_signature(field_name, field)
if field_name in merged_params or param_name in merged_params:
continue
if not is_valid_identifier(param_name):
if allow_names:
param_name = field_name
else:
use_var_kw = True
continue
if field.is_required():
default = Parameter.empty
elif field.default_factory is not None:
# Mimics stdlib dataclasses:
default = _HAS_DEFAULT_FACTORY
else:
default = field.default
merged_params[param_name] = Parameter(
param_name,
Parameter.KEYWORD_ONLY,
annotation=field.rebuild_annotation(),
default=default,
)
if extra == 'allow':
use_var_kw = True
if var_kw and use_var_kw:
# Make sure the parameter for extra kwargs
# does not have the same name as a field
default_model_signature = [
('self', Parameter.POSITIONAL_ONLY),
('data', Parameter.VAR_KEYWORD),
]
if [(p.name, p.kind) for p in present_params] == default_model_signature:
# if this is the standard model signature, use extra_data as the extra args name
var_kw_name = 'extra_data'
else:
# else start from var_kw
var_kw_name = var_kw.name
# generate a name that's definitely unique
while var_kw_name in fields:
var_kw_name += '_'
merged_params[var_kw_name] = var_kw.replace(name=var_kw_name)
return merged_params
def generate_pydantic_signature(
init: Callable[..., None],
fields: dict[str, FieldInfo],
populate_by_name: bool,
extra: ExtraValues | None,
is_dataclass: bool = False,
) -> Signature:
"""Generate signature for a pydantic BaseModel or dataclass.
Args:
init: The class init.
fields: The model fields.
populate_by_name: The `populate_by_name` value of the config.
extra: The `extra` value of the config.
is_dataclass: Whether the model is a dataclass.
Returns:
The dataclass/BaseModel subclass signature.
"""
merged_params = _generate_signature_parameters(init, fields, populate_by_name, extra)
if is_dataclass:
merged_params = {k: _process_param_defaults(v) for k, v in merged_params.items()}
return Signature(parameters=list(merged_params.values()), return_annotation=None)
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