Source code for dataclass_wizard.bases_meta
"""
Ideally should be in the `bases` module, however we'll run into a Circular
Import scenario if we move it there, since the `loaders` and `dumpers` modules
both import directly from `bases`.
"""
from __future__ import annotations
import logging
import warnings
from datetime import datetime, date
from typing import Mapping
from .bases import AbstractMeta, META, AbstractEnvMeta
from .class_helper import (
META_INITIALIZER, _META, get_meta,
get_outer_class_name, get_class_name, create_new_class,
json_field_to_dataclass_field, dataclass_field_to_json_field,
field_to_env_var,
DATACLASS_FIELD_TO_ALIAS_FOR_LOAD,
DATACLASS_FIELD_TO_ENV_FOR_LOAD,
DATACLASS_FIELD_TO_ALIAS_FOR_DUMP,
)
from .decorators import try_with_load
from .enums import DateTimeTo, LetterCase, LetterCasePriority
from .errors import ParseError, show_deprecation_warning
from .loader_selection import get_dumper, get_loader
from .log import LOG
from .type_def import E
from .utils.type_conv import date_to_timestamp, as_enum
ALLOWED_MODES = ('runtime', 'v1_codegen')
# global flag to determine if debug mode was ever enabled
_debug_was_enabled = False
[docs]
def register_type(cls, tp, *, load=None, dump=None, mode=None) -> None:
meta = get_meta(cls)
if meta.v1:
if load is None:
load = tp
if dump is None:
dump = str
if (load_hook := meta.v1_type_to_load_hook) is None:
meta.v1_type_to_load_hook = load_hook = {}
if (dump_hook := meta.v1_type_to_dump_hook) is None:
meta.v1_type_to_dump_hook = dump_hook = {}
load_hook[tp] = (mode if mode else _infer_mode(load), load)
dump_hook[tp] = (mode if mode else _infer_mode(dump), dump)
else:
from .dumpers import DumpMixin
from .loaders import LoadMixin
dumper = get_dumper(cls, base_cls=DumpMixin)
loader = get_loader(cls, base_cls=LoadMixin)
# default hooks
load = tp if load is None else load
dump = str if dump is None else dump
# adapt to what v0 expects
load = _adapt_to_arity(load, loader.HOOK_ARITY)
dump = _adapt_to_arity(dump, dumper.HOOK_ARITY)
dumper.register_dump_hook(tp, dump)
loader.register_load_hook(tp, load)
# use `debug_enabled` for log level if it's a str or int.
def _enable_debug_mode_if_needed(v1, cls_loader, possible_lvl):
global _debug_was_enabled
if not _debug_was_enabled:
_debug_was_enabled = True
# use `debug_enabled` for log level if it's a str or int.
default_lvl = logging.DEBUG
# minimum logging level for logs by this library.
min_level = default_lvl if isinstance(possible_lvl, bool) else possible_lvl
# set the logging level of this library's logger.
LOG.setLevel(min_level)
LOG.info('DEBUG Mode is enabled')
# Decorate all hooks so they format more helpful messages
# on error.
if not v1:
load_hooks = cls_loader.__LOAD_HOOKS__
for typ in load_hooks:
load_hooks[typ] = try_with_load(load_hooks[typ])
def _as_enum_safe(cls: type, name: str, base_type: type[E]) -> 'E | None':
"""
Attempt to return the value for class attribute :attr:`attr_name` as
a :type:`base_type`.
:raises ParseError: If we are unable to convert the value of the class
attribute to an Enum of type `base_type`.
"""
try:
return as_enum(getattr(cls, name), base_type)
except ParseError as e:
# We run into a parsing error while loading the enum; Add
# additional info on the Exception object before re-raising it
e.class_name = get_class_name(cls)
e.field_name = name
raise
def _arity(hook) -> int:
# Python function / method
code = getattr(hook, "__code__", None)
if code is not None:
# reject *args/**kwargs if you want strictness
if code.co_flags & 0x04 or code.co_flags & 0x08:
return -1
return code.co_argcount
# Classes / C-callables (e.g., IPv4Address) don't expose __code__.
# Treat as "callable(value)" i.e., 1-arg constructor.
return 1
def _adapt_to_arity(fn, target_arity: int):
src = _arity(fn)
if src == -1:
# If they already accept *args/**kwargs, it will work everywhere.
return fn
if src == target_arity:
return fn
# Common case: user gives 1-arg callable but backend passes extra info
if src == 1 and target_arity > 1:
def wrapper(x, *rest):
return fn(x)
return wrapper
# Less common: user gives 2-arg (v1 codegen) but v0 expects 1
# You can reject this unless you have a sane mapping.
raise TypeError(
f"Hook {getattr(fn, '__name__', fn)!r} has {src} args, "
f"but backend expects {target_arity}."
)
def _infer_mode(hook) -> str:
code = getattr(hook, '__code__', None)
if code is None:
return 'runtime' # types/builtins
co_flags = code.co_flags
if co_flags & 0x04 or co_flags & 0x08:
raise TypeError('hooks must not use *args/**kwargs')
argc = code.co_argcount
if argc == 1:
return 'runtime'
if argc == 2:
return 'v1_codegen'
raise TypeError('hook must accept 1 arg (runtime) or 2 args (TypeInfo, Extras)')
def _normalize_hooks(hooks: Mapping | None) -> None:
if not hooks:
return
for tp, hook in hooks.items():
if isinstance(hook, tuple):
if len(hook) != 2:
raise ValueError(f"hook tuple must be (mode, hook), got {hook!r}") from None
mode, fn = hook
if mode not in ALLOWED_MODES:
raise ValueError(
f"mode must be 'runtime' or 'v1_codegen' (got {mode!r})"
) from None
else:
mode = _infer_mode(hook)
# noinspection PyUnresolvedReferences
hooks[tp] = mode, hook
[docs]
class BaseJSONWizardMeta(AbstractMeta):
"""
Superclass definition for the `JSONWizard.Meta` inner class.
See the implementation of the :class:`AbstractMeta` class for the
available config that can be set, as well as for descriptions on any
implemented methods.
"""
__slots__ = ()
@classmethod
def _init_subclass(cls):
"""
Hook that should ideally be run whenever the `Meta` class is
sub-classed.
"""
outer_cls_name = get_outer_class_name(cls, raise_=False)
# We can retrieve the outer class name using `__qualname__`, but it's
# not easy to find the class definition itself. The simplest way seems
# to be to create a new callable (essentially a class method for the
# outer class) which will later be called by the base enclosing class.
#
# Note that this relies on the observation that the
# `__init_subclass__` method of any inner classes are run before the
# one for the outer class.
if outer_cls_name is not None:
META_INITIALIZER[outer_cls_name] = cls.bind_to
else:
from .abstractions import AbstractJSONWizard
# The `Meta` class is defined as an outer class. Emit a warning
# here, just so we can ensure awareness of this special case.
LOG.warning('The %r class is not declared as an Inner Class, so '
'these are global settings that will apply to all '
'JSONSerializable sub-classes.', get_class_name(cls))
# Copy over global defaults to the :class:`AbstractMeta`
for attr in AbstractMeta.fields_to_merge:
setattr(AbstractMeta, attr, getattr(cls, attr, None))
if cls.json_key_to_field:
AbstractMeta.json_key_to_field = cls.json_key_to_field
if cls.v1_field_to_alias:
AbstractMeta.v1_field_to_alias = cls.v1_field_to_alias
if cls.v1_field_to_alias_dump:
AbstractMeta.v1_field_to_alias_dump = cls.v1_field_to_alias_dump
if cls.v1_field_to_alias_load:
AbstractMeta.v1_field_to_alias_load = cls.v1_field_to_alias_load
# Create a new class of `Type[W]`, and then pass `create=False` so
# that we don't create new loader / dumper for the class.
new_cls = create_new_class(cls, (AbstractJSONWizard, ))
cls.bind_to(new_cls, create=False)
[docs]
@classmethod
def bind_to(cls, dataclass: type, create=True, is_default=True,
base_loader=None,
base_dumper=None):
from .v1.enums import KeyAction, KeyCase, DateTimeTo as V1DateTimeTo
meta = get_meta(dataclass)
v1 = cls.v1 or meta.v1
cls_loader = get_loader(dataclass, create=create,
base_cls=base_loader, v1=v1)
cls_dumper = get_dumper(dataclass, create=create,
base_cls=base_dumper, v1=v1)
if cls.v1_debug:
_enable_debug_mode_if_needed(v1, cls_loader, cls.v1_debug)
elif cls.debug_enabled:
show_deprecation_warning(
'debug_enabled',
fmt="Deprecated Meta setting {name} ({reason}).",
reason='Use `v1_debug` instead',
)
_enable_debug_mode_if_needed(v1, cls_loader, cls.debug_enabled)
if cls.json_key_to_field is not None:
add_for_both = cls.json_key_to_field.pop('__all__', None)
json_field_to_dataclass_field(dataclass).update(
cls.json_key_to_field
)
if add_for_both:
dataclass_to_json_field = dataclass_field_to_json_field(
dataclass)
# We unfortunately can't use a dict comprehension approach, as
# we don't know if there are multiple JSON keys mapped to a
# single dataclass field. So to be safe, we should only set
# the first JSON key mapped to each dataclass field.
for json_key, field in cls.json_key_to_field.items():
if field not in dataclass_to_json_field:
dataclass_to_json_field[field] = json_key
if cls.v1_dump_date_time_as is not None:
cls.v1_dump_date_time_as = _as_enum_safe(cls, 'v1_dump_date_time_as', V1DateTimeTo)
if cls.marshal_date_time_as is not None:
enum_val = _as_enum_safe(cls, 'marshal_date_time_as', DateTimeTo)
if enum_val is DateTimeTo.TIMESTAMP:
# Update dump hooks for the `datetime` and `date` types
cls_dumper.dump_with_datetime = lambda o, *_: round(o.timestamp())
cls_dumper.dump_with_date = lambda o, *_: date_to_timestamp(o)
cls_dumper.register_dump_hook(
datetime, cls_dumper.dump_with_datetime)
cls_dumper.register_dump_hook(
date, cls_dumper.dump_with_date)
elif enum_val is DateTimeTo.ISO_FORMAT:
# noop; the default dump hook for `datetime` and `date`
# already serializes using this approach.
pass
if cls.key_transform_with_load is not None:
cls_loader.transform_json_field = _as_enum_safe(
cls, 'key_transform_with_load', LetterCase)
if (key_case := cls.v1_case) is not None:
cls.v1_load_case = cls.v1_dump_case = key_case
cls.v1_case = None
if cls.v1_load_case is not None:
cls_loader.transform_json_field = _as_enum_safe(
cls, 'v1_load_case', KeyCase)
if cls.v1_dump_case is not None:
cls_dumper.transform_dataclass_field = _as_enum_safe(
cls, 'v1_dump_case', KeyCase)
if (field_to_alias := cls.v1_field_to_alias) is not None:
cls.v1_field_to_alias_dump = {
k: v if isinstance(v, str) else v[0]
for k, v in field_to_alias.items()
}
cls.v1_field_to_alias_load = field_to_alias
if (field_to_alias := cls.v1_field_to_alias_dump) is not None:
DATACLASS_FIELD_TO_ALIAS_FOR_DUMP[dataclass].update(field_to_alias)
if (field_to_alias := cls.v1_field_to_alias_load) is not None:
DATACLASS_FIELD_TO_ALIAS_FOR_LOAD[dataclass].update({
k: (v, ) if isinstance(v, str) else v
for k, v in field_to_alias.items()
})
if cls.key_transform_with_dump is not None:
cls_dumper.transform_dataclass_field = _as_enum_safe(
cls, 'key_transform_with_dump', LetterCase)
if cls.v1_on_unknown_key is not None:
cls.v1_on_unknown_key = _as_enum_safe(cls, 'v1_on_unknown_key', KeyAction)
_normalize_hooks(cls.v1_type_to_load_hook)
_normalize_hooks(cls.v1_type_to_dump_hook)
# Finally, if needed, save the meta config for the outer class. This
# will allow us to access this config as part of the JSON load/dump
# process if needed.
if is_default:
# Check if the dataclass already has a Meta config; if so, we need to
# copy over special attributes so they don't get overwritten.
if dataclass in _META:
_META[dataclass] &= cls
else:
_META[dataclass] = cls
[docs]
class BaseEnvWizardMeta(AbstractEnvMeta):
"""
Superclass definition for the `EnvWizard.Meta` inner class.
See the implementation of the :class:`AbstractEnvMeta` class for the
available config that can be set, as well as for descriptions on any
implemented methods.
"""
__slots__ = ()
@classmethod
def _init_subclass(cls):
"""
Hook that should ideally be run whenever the `Meta` class is
sub-classed.
"""
outer_cls_name = get_outer_class_name(cls, raise_=False)
if outer_cls_name is not None:
META_INITIALIZER[outer_cls_name] = cls.bind_to
else:
from .abstractions import AbstractJSONWizard
# The `Meta` class is defined as an outer class. Emit a warning
# here, just so we can ensure awareness of this special case.
LOG.warning('The %r class is not declared as an Inner Class, so '
'these are global settings that will apply to all '
'EnvWizard sub-classes.', get_class_name(cls))
# Copy over global defaults to the :class:`AbstractMeta`
for attr in AbstractEnvMeta.fields_to_merge:
setattr(AbstractEnvMeta, attr, getattr(cls, attr, None))
if cls.field_to_env_var:
AbstractEnvMeta.field_to_env_var = cls.field_to_env_var
if cls.v1_field_to_alias_dump:
AbstractEnvMeta.v1_field_to_alias_dump = cls.v1_field_to_alias_dump
if cls.v1_field_to_env_load:
AbstractEnvMeta.v1_field_to_env_load = cls.v1_field_to_env_load
# Create a new class of `Type[W]`, and then pass `create=False` so
# that we don't create new loader / dumper for the class.
new_cls = create_new_class(cls, (AbstractJSONWizard, ))
cls.bind_to(new_cls, create=False)
[docs]
@classmethod
def bind_to(cls, env_class: type, create=True, is_default=True):
from .v1.enums import KeyCase, EnvKeyStrategy, EnvPrecedence
meta = get_meta(env_class)
v1 = cls.v1 or meta.v1
cls_loader = get_loader(
env_class,
create=create,
env=True,
v1=v1)
cls_dumper = get_dumper(
env_class,
create=create,
v1=v1)
if cls.v1_debug:
_enable_debug_mode_if_needed(v1, cls_loader, cls.v1_debug)
if cls.debug_enabled:
_enable_debug_mode_if_needed(v1, cls_loader, cls.debug_enabled)
if cls.field_to_env_var is not None:
if v1:
warnings.warn(
'`field_to_env_var` is deprecated and will be removed in v1. '
'Use `v1_field_to_env_load` instead.',
FutureWarning,
stacklevel=2,
)
cls.v1_field_to_env_load = cls.field_to_env_var
else:
field_to_env_var(env_class).update(
cls.field_to_env_var
)
cls.key_lookup_with_load = _as_enum_safe(
cls, 'key_lookup_with_load', LetterCasePriority)
if v1:
from . import EnvWizard as V0EnvWizard
from .v1 import EnvWizard as V1EnvWizard
if issubclass(env_class, V0EnvWizard) and not issubclass(env_class, V1EnvWizard):
raise TypeError(
f'{env_class.__qualname__} is using Meta(v1=True) but does '
'not inherit from `dataclass_wizard.v1.EnvWizard`.\n\n'
'Fix:\n'
' from dataclass_wizard.v1 import EnvWizard'
) from None
if cls.v1_load_case is not None:
cls.v1_load_case = _as_enum_safe(
cls, 'v1_load_case', EnvKeyStrategy)
if cls.v1_env_precedence is not None:
cls.v1_env_precedence = _as_enum_safe(
cls, 'v1_env_precedence', EnvPrecedence)
# TODO
cls_dumper.transform_dataclass_field = _as_enum_safe(
cls, 'v1_dump_case', KeyCase)
if (field_to_alias := cls.v1_field_to_alias_dump) is not None:
DATACLASS_FIELD_TO_ALIAS_FOR_DUMP[env_class].update(field_to_alias)
if (field_to_env := cls.v1_field_to_env_load) is not None:
DATACLASS_FIELD_TO_ENV_FOR_LOAD[env_class].update({
k: (v, ) if isinstance(v, str) else v
for k, v in field_to_env.items()
})
# set this attribute in case of nested dataclasses (which
# uses codegen in `v1/loaders.py`)
cls.v1_on_unknown_key = None
# if cls.v1_on_unknown_key is not None:
# cls.v1_on_unknown_key = _as_enum_safe(cls, 'v1_on_unknown_key', KeyAction)
_normalize_hooks(cls.v1_type_to_load_hook)
_normalize_hooks(cls.v1_type_to_dump_hook)
else:
cls_dumper.transform_dataclass_field = _as_enum_safe(
cls, 'key_transform_with_dump', LetterCase)
# Finally, if needed, save the meta config for the outer class. This
# will allow us to access this config as part of the JSON load/dump
# process if needed.
if is_default:
# Check if the dataclass already has a Meta config; if so, we need to
# copy over special attributes so they don't get overwritten.
if env_class in _META:
_META[env_class] &= cls
else:
_META[env_class] = cls
# noinspection PyPep8Naming
[docs]
def LoadMeta(**kwargs) -> META:
"""
Helper function to setup the ``Meta`` Config for the JSON load
(de-serialization) process, which is intended for use alongside the
``fromdict`` helper function.
For descriptions on what each of these params does, refer to the `Docs`_
below, or check out the :class:`AbstractMeta` definition (I want to avoid
duplicating the descriptions for params here).
Examples::
>>> LoadMeta(key_transform='CAMEL').bind_to(MyClass)
>>> fromdict(MyClass, {"myStr": "value"})
.. _Docs: https://dcw.ritviknag.com/en/latest/common_use_cases/meta.html
"""
base_dict = kwargs | {'__slots__': ()}
if (v := base_dict.pop('key_transform', None)) is not None:
base_dict['key_transform_with_load'] = v
if (v := base_dict.pop('v1_case', None)) is not None:
base_dict['v1_load_case'] = v
if (v := base_dict.pop('v1_field_to_alias', None)) is not None:
base_dict['v1_field_to_alias_load'] = v
if (v := base_dict.pop('v1_type_to_hook', None)) is not None:
base_dict['v1_type_to_load_hook'] = v
# Create a new subclass of :class:`AbstractMeta`
# noinspection PyTypeChecker
return type('Meta', (BaseJSONWizardMeta, ), base_dict)
# noinspection PyPep8Naming
[docs]
def DumpMeta(**kwargs) -> META:
"""
Helper function to setup the ``Meta`` Config for the JSON dump
(serialization) process, which is intended for use alongside the
``asdict`` helper function.
For descriptions on what each of these params does, refer to the `Docs`_
below, or check out the :class:`AbstractMeta` definition (I want to avoid
duplicating the descriptions for params here).
Examples::
>>> DumpMeta(key_transform='CAMEL').bind_to(MyClass)
>>> asdict(MyClass, {"myStr": "value"})
.. _Docs: https://dcw.ritviknag.com/en/latest/common_use_cases/meta.html
"""
# Set meta attributes here.
base_dict = kwargs | {'__slots__': ()}
if (v := base_dict.pop('key_transform', None)) is not None:
base_dict['key_transform_with_dump'] = v
if (v := base_dict.pop('v1_case', None)) is not None:
base_dict['v1_dump_case'] = v
if (v := base_dict.pop('v1_field_to_alias', None)) is not None:
base_dict['v1_field_to_alias_dump'] = v
if (v := base_dict.pop('v1_type_to_hook', None)) is not None:
base_dict['v1_type_to_dump_hook'] = v
# Create a new subclass of :class:`AbstractMeta`
# noinspection PyTypeChecker
return type('Meta', (BaseJSONWizardMeta, ), base_dict)
# noinspection PyPep8Naming
[docs]
def EnvMeta(**kwargs) -> META:
"""
Helper function to setup the ``Meta`` Config for the EnvWizard.
For descriptions on what each of these params does, refer to the `Docs`_
below, or check out the :class:`AbstractEnvMeta` definition (I want to avoid
duplicating the descriptions for params here).
Examples::
>>> EnvMeta(key_transform_with_dump='SNAKE').bind_to(MyClass)
.. _Docs: https://dcw.ritviknag.com/en/latest/common_use_cases/meta.html
"""
# Set meta attributes here.
base_dict = kwargs | {'__slots__': ()}
# Create a new subclass of :class:`AbstractMeta`
# noinspection PyTypeChecker
return type('EnvMeta', (BaseEnvWizardMeta, ), base_dict)
