def coerce_value(self, value: Any, annotation: Any) -> Any:
"""Coerce the given value to the given annotation, if possible.
Checks for:
- :class:`datetime.date`
- :class:`datetime.datetime`
- builtin types
- extended type annotations as described in the ``typing`` module.
- Classes with a ``from_dict`` method
Parameters
----------
value :
The value to be coerced
annotation :
The provided annotation for determining the coercion
"""
# Resolve NewTypes into their annotation. Recursive.
annotation = checks.resolve_supertype(annotation)
# Get the "origin" of the annotation. This will be a builtin for native types.
# For custom types or classes, this will be the same as the annotation.
origin = self.get_origin(annotation)
optional = checks.isoptionaltype(annotation)
args = set(self.get_args(annotation))
# Short-circuit checks if this is an optional type and the value is None
# Or if the type of the value is the annotation.
if ((checks.isinstance(value, origin) and not args)
or (optional and value is None)
or (origin is Union
and any(checks.isinstance(value, x) for x in args))):
return value
coerced = self.registry.coerce(value, origin, annotation)
return coerced
def _evaluate_contraints(self):
type = self.t
if checks.isoptionaltype(type):
args = util.get_args(type)[:-1]
type = args[0] if len(args) == 1 else Union[args]
self.nullable = True
self.t = type
c = self.factory(type, nullable=self.nullable, name=self.name)
return c
def _coerce_class(self, value: Any, origin: Type, annotation: Any) -> Any:
value = self._pre_process_class(value, origin)
coerced = value
if isinstance(value, (Mapping, dict)):
coerced = origin(**value)
elif value is not None and not checks.isoptionaltype(annotation):
coerced = origin(value)
return coerced
def get_constraints(
t: Type[VT],
*,
nullable: bool = False,
name: str = None,
cls: Optional[Type] = ..., # type: ignore
) -> ConstraintsProtocolT[VT]:
while should_unwrap(t):
nullable = nullable or isoptionaltype(t)
t = get_args(t)[0]
if t is cls or t in __stack:
dc = DelayedConstraints(
t, nullable=nullable, name=name, factory=get_constraints
)
return cast(ConstraintsProtocolT, dc)
if isforwardref(t):
if cls is ...: # pragma: nocover
raise TypeError(
f"Cannot build constraints for {t} without an enclosing class."
)
fdc = ForwardDelayedConstraints(
t, # type: ignore
cls.__module__,
localns=getattr(cls, "__dict__", {}).copy(),
nullable=nullable,
name=name,
factory=get_constraints,
)
return cast(ConstraintsProtocolT, fdc)
if isconstrained(t):
c: ConstraintsProtocolT = t.__constraints__ # type: ignore
if (c.name, c.nullable) != (name, nullable):
return dataclasses.replace(c, name=name, nullable=nullable)
return c
if isenumtype(t):
ec = _from_enum_type(t, nullable=nullable, name=name) # type: ignore
return cast(ConstraintsProtocolT, ec)
if isabstract(t):
return cast(
ConstraintsProtocolT, _from_strict_type(t, nullable=nullable, name=name)
)
if isnamedtuple(t) or istypeddict(t):
handler = _from_class
else:
ot = origin(t)
if ot in {type, abc.Callable}:
handler = _from_strict_type # type: ignore
t = ot
else:
handler = _CONSTRAINT_BUILDER_HANDLERS.get_by_parent(ot, _from_class) # type: ignore
__stack.add(t)
c = handler(t, nullable=nullable, name=name, cls=cls)
__stack.clear()
return c
def _from_union(
t: Type[VT], *, nullable: bool = False, name: str = None, cls: Type = None
) -> ConstraintsProtocolT:
_nullable: bool = isoptionaltype(t)
nullable = nullable or _nullable
_args = get_args(t)[:-1] if _nullable else get_args(t)
if len(_args) == 1:
return get_constraints(_args[0], nullable=nullable, name=name, cls=cls)
c = MultiConstraints(
(*(get_constraints(a, nullable=nullable, cls=cls) for a in _args),),
name=name,
tag=get_tag_for_types(_args),
)
return cast(ConstraintsProtocolT, c)
def _evaluate_contraints(self):
globalns = sys.modules[self.module].__dict__.copy()
try:
type = evaluate_forwardref(self.ref, globalns or {}, self.localns
or {})
except NameError as e: # pragma: nocover
warnings.warn(
f"Counldn't resolve forward reference: {e}. "
f"Make sure this type is available in {self.module}.")
type = object # make it a no-op
if checks.isoptionaltype(type):
args = util.get_args(type)[:-1]
type = args[0] if len(args) == 1 else Union[args]
self.nullable = True
c = self.factory(type, nullable=self.nullable, name=self.name)
return c
def get_origin(cls, annotation: Any) -> Any:
"""Get origins for subclasses of typing._SpecialForm, recursive"""
# Resolve custom NewTypes, recursively.
actual = checks.resolve_supertype(annotation)
# Extract the origin of the annotation, recursively.
actual = getattr(actual, "__origin__", actual)
if checks.isoptionaltype(annotation) or checks.isclassvartype(
annotation):
args = cls.get_args(annotation)
return cls.get_origin(args[0]) if args else actual
# provide defaults for generics
if not checks.isbuiltintype(actual):
actual = cls._check_generics(actual)
return actual
def _resolve_params(
cls: Type,
**param: inspect.Parameter,
) -> Mapping[str, ConstraintsProtocolT]:
items: Dict[str, ConstraintsProtocolT] = {}
while param:
name, p = param.popitem()
anno = p.annotation
nullable = p.default in (None, Ellipsis) or isoptionaltype(anno)
if anno in {Any, Ellipsis, p.empty}:
continue
if isuniontype(anno) and not isforwardref(anno):
items[name] = _from_union(anno, nullable=nullable, name=name, cls=cls)
continue
else:
items[name] = get_constraints(anno, nullable=nullable, name=name, cls=cls)
return items
def check(
self,
origin: Type,
annotation: Any,
*,
name: str = None,
default: Any = _Empty,
param_kind: inspect._ParameterKind = _Empty,
) -> ResolvedAnnotation:
"""Locate the coercer for this annotation from either registry."""
key = self.key(annotation, default=default, param_kind=param_kind)
if key not in self.__annotation_registry:
use = annotation
is_optional = checks.isoptionaltype(annotation)
if is_optional or (checks.isclassvartype(annotation)
and getattr(annotation, "__args__", ())):
use = annotation.__args__[0]
coercer = self._check(
reg=self.__user_registry + self.__registry,
origin=origin,
annotation=use,
)
anno = (ResolvedAnnotation(
annotation=use,
origin=origin,
un_resolved=annotation,
coercer=coercer,
name=name,
default=default,
param_kind=param_kind,
is_optional=is_optional,
) if coercer else None)
self.__annotation_registry[key] = anno
return self.__annotation_registry[key]
def annotation(
self,
annotation: Type[ObjectT],
name: str = None,
parameter: Optional[inspect.Parameter] = None,
is_optional: bool = None,
is_strict: StrictModeT = None,
flags: "SerdeFlags" = None,
default: Any = EMPTY,
namespace: Type = None,
) -> AnnotationT:
"""Get a :py:class:`Annotation` for this type.
Unlike a :py:class:`ResolvedAnnotation`, this does not provide access to a
serializer/deserializer/validator protocol.
"""
flags = cast(
"SerdeFlags",
getattr(annotation, SERDE_FLAGS_ATTR, flags or SerdeFlags()))
if parameter is None:
parameter = inspect.Parameter(
name or "_",
inspect.Parameter.POSITIONAL_OR_KEYWORD,
annotation=annotation,
default=default if checks.ishashable(default) else ...,
)
# Check for the super-type
non_super = util.resolve_supertype(annotation)
# Note, this may be a generic, like Union.
orig = util.origin(annotation)
use = non_super
# Get the unfiltered args
args = getattr(non_super, "__args__", None)
# Set whether this is optional/strict
is_optional = (is_optional or checks.isoptionaltype(non_super)
or parameter.default in self.OPTIONALS)
is_strict = is_strict or checks.isstrict(non_super) or self.STRICT
is_static = util.origin(use) not in self._DYNAMIC
is_literal = checks.isliteral(use)
# Determine whether we should use the first arg of the annotation
while checks.should_unwrap(use) and args:
is_optional = is_optional or checks.isoptionaltype(use)
is_strict = is_strict or checks.isstrict(use)
if is_optional and len(args) > 2:
# We can't resolve this annotation.
is_static = False
use = Union[args[:-1]]
break
# Note that we don't re-assign `orig`.
# This is intentional.
# Special forms are needed for building the downstream validator.
# Callers should be aware of this and perhaps use `util.origin` elsewhere.
non_super = util.resolve_supertype(args[0])
use = non_super
args = util.get_args(use)
is_static = util.origin(use) not in self._DYNAMIC
is_literal = is_literal or checks.isliteral(use)
# Only allow legal parameters at runtime, this has implementation implications.
if is_literal:
args = util.get_args(use)
if any(not isinstance(a, self.LITERALS) for a in args):
raise TypeError(
f"PEP 586: Unsupported parameters for 'Literal' type: {args}. "
"See https://www.python.org/dev/peps/pep-0586/"
"#legal-parameters-for-literal-at-type-check-time "
"for more information.")
# The type definition doesn't exist yet.
if use.__class__ is ForwardRef:
module, localns = self.__module__, {}
# Ideally we have a namespace from a parent class/function to the field
if namespace:
module = namespace.__module__
localns = getattr(namespace, "__dict__", {})
return ForwardDelayedAnnotation(
ref=use,
resolver=self,
_name=name,
parameter=parameter,
is_optional=is_optional,
is_strict=is_strict,
flags=flags,
default=default,
module=module,
localns=localns,
)
# The type definition is recursive or within a recursive loop.
elif use is namespace or use in self.__stack:
# If detected via stack, we can remove it now.
# Otherwise we'll cause another recursive loop.
if use in self.__stack:
self.__stack.remove(use)
return DelayedAnnotation(
type=use,
resolver=self,
_name=name,
parameter=parameter,
is_optional=is_optional,
is_strict=is_strict,
flags=flags,
default=default,
)
# Otherwise, add this type to the stack to prevent a recursive loop from elsewhere.
if not checks.isstdlibtype(use):
self.__stack.add(use)
serde = (self._get_configuration(util.origin(use), flags)
if is_static and not is_literal else SerdeConfig(flags))
anno = Annotation(
resolved=use,
origin=orig,
un_resolved=annotation,
parameter=parameter,
optional=is_optional,
strict=is_strict,
static=is_static,
serde=serde,
)
anno.translator = functools.partial(self.translator.factory,
anno) # type: ignore
return anno
