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import functools
import itertools
from typing import (
Callable,
ClassVar,
Dict,
List,
Optional,
Sequence,
Tuple,
Type,
Union,
cast,
)
from django.core.exceptions import ValidationError
from django.db import models
from .types import IntegerChoicesFlag
def _get_flag_description(descs: Sequence[str]) -> str:
return "|".join(str(desc) for desc in descs)
def _get_integer_enum_members(choices: List[Tuple[Union[int, None], str]]) -> Dict[str, int]:
# choices can contain the `None` key which can't be mapped to an enum. See
# Django Model Field docs about Enumeration Types for more info about
# labelling empty states with `__empty__`.
filtered_choices = [(k, v) for (k, v) in choices if k is not None]
return {desc.replace(" ", "_").upper(): value for value, desc in filtered_choices}
try:
from django.utils.functional import Promise, lazy
except ImportError: # pragma: nocover
Promise = None
_get_flag_description_lazy = None
else:
_get_flag_description_lazy = cast(
Callable[[Sequence[str]], str],
lazy(_get_flag_description, str),
)
class TextChoicesField(models.CharField):
description: ClassVar[str] = "TextChoices"
default_error_messages: ClassVar[Dict[str, str]] = {
"invalid": "“%(value)s” must be a subclass of %(enum)s.",
}
def __init__(
self,
choices_enum: Optional[Type[models.TextChoices]] = None,
verbose_name: Optional[str] = None,
name: Optional[str] = None,
**kwargs,
):
if choices_enum is not None:
self.choices_enum = choices_enum
if getattr(self, "null", False) or kwargs.get("null"):
kwargs["choices"] = choices_enum.choices
else:
kwargs["choices"] = [
(k, v) for (k, v) in choices_enum.choices if cast(object, k) is not None
]
elif "choices" in kwargs:
self.choices_enum = models.TextChoices(
"ChoicesEnum",
[(k, (k, v)) for k, v in kwargs["choices"] if k is not None],
)
else:
raise TypeError("either of choices_enum or choices must be provided")
kwargs.setdefault(
"max_length",
max(len(c[0]) for c in kwargs["choices"] if c[0] is not None),
)
super().__init__(verbose_name=verbose_name, name=name, **kwargs)
def to_python(self, value):
if value in self.empty_values:
return None
try:
return self.choices_enum(value)
except ValueError as e:
raise ValidationError(
self.error_messages["invalid"],
code="invalid",
params={"value": value, "enum": self.choices_enum},
) from e
def from_db_value(self, value, expression, connection):
return self.to_python(value)
def get_prep_value(self, value):
value = super().get_prep_value(value)
return self.to_python(value)
class IntegerChoicesField(models.IntegerField):
description: ClassVar[str] = "IntegerChoices"
default_error_messages: ClassVar[Dict[str, str]] = {
"invalid": "“%(value)s” must be a subclass of %(enum)s.",
}
def __init__(
self,
choices_enum: Optional[Type[models.IntegerChoices]] = None,
verbose_name: Optional[str] = None,
name: Optional[str] = None,
**kwargs,
):
if choices_enum is not None:
self.choices_enum = choices_enum
if getattr(self, "null", False) or kwargs.get("null"):
kwargs["choices"] = choices_enum.choices
else:
kwargs["choices"] = [
(k, v) for (k, v) in choices_enum.choices if cast(object, k) is not None
]
elif "choices" in kwargs:
enum_members = _get_integer_enum_members(kwargs["choices"])
self.choices_enum = models.IntegerChoices("ChoicesEnum", enum_members)
else:
raise TypeError("either of choices_enum or choices must be provided")
super().__init__(verbose_name=verbose_name, name=name, **kwargs)
def to_python(self, value):
if value is None:
return None
try:
return self.choices_enum(int(value) if isinstance(value, str) else value)
except ValueError as e:
raise ValidationError(
self.error_messages["invalid"],
code="invalid",
params={"value": value, "enum": self.choices_enum},
) from e
def from_db_value(self, value, expression, connection):
return self.to_python(value)
def get_prep_value(self, value):
value = super().get_prep_value(value)
return self.to_python(value)
def formfield(self, **kwargs): # pragma:nocover
return super().formfield(
**{
"coerce": self.to_python,
**kwargs,
},
)
class IntegerChoicesFlagField(models.IntegerField):
description: ClassVar[str] = "IntegerChoicesFlag"
default_error_messages: ClassVar[Dict[str, str]] = {
"invalid": "“%(value)s” must be a subclass of %(enum)s.",
}
def __init__(
self,
choices_enum: Optional[Type[IntegerChoicesFlag]] = None,
verbose_name: Optional[str] = None,
name: Optional[str] = None,
**kwargs,
):
if choices_enum is not None:
self.choices_enum = choices_enum
if getattr(self, "null", False) or kwargs.get("null"):
kwargs["choices"] = choices_enum.choices
else:
kwargs["choices"] = [
(k, v) for (k, v) in choices_enum.choices if cast(object, k) is not None
]
default_choices = [(x.value, x.label) for x in choices_enum]
for i in range(1, len(default_choices)):
for combination in itertools.combinations(default_choices, i + 1):
value = functools.reduce(lambda a, b: a | b[0], combination, 0)
descs = [c[1] for c in combination]
if Promise is not None and any(isinstance(desc, Promise) for desc in descs):
assert _get_flag_description_lazy is not None
desc = _get_flag_description_lazy(descs)
else:
desc = _get_flag_description(descs)
kwargs["choices"].append((value, desc))
elif "choices" in kwargs:
default_choices_length = len(kwargs["choices"]).bit_length()
default_choices = [kwargs["choices"][i] for i in range(default_choices_length)]
enum_members = _get_integer_enum_members(default_choices)
self.choices_enum = models.IntegerChoices("ChoicesEnum", enum_members)
else:
raise TypeError("either of choices_enum or choices must be provided")
super().__init__(verbose_name=verbose_name, name=name, **kwargs)
def to_python(self, value):
if value is None:
return None
try:
return self.choices_enum(int(value) if isinstance(value, str) else value)
except ValueError as e:
raise ValidationError(
self.error_messages["invalid"],
code="invalid",
params={"value": value, "enum": self.choices_enum},
) from e
def from_db_value(self, value, expression, connection):
return self.to_python(value)
def get_prep_value(self, value):
value = super().get_prep_value(value)
return self.to_python(value)
def formfield(self, **kwargs): # pragma:nocover
return super().formfield(
**{
"coerce": self.to_python,
**kwargs,
},
)
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