from __future__ import annotations from collections import Counter, deque from collections.abc import Callable, Iterable from collections.abc import Mapping as AbcMapping from collections.abc import MutableMapping as AbcMutableMapping from dataclasses import Field from enum import Enum from inspect import Signature from inspect import signature as inspect_signature from pathlib import Path from typing import Any, Optional, Tuple, TypeVar, overload from attrs import Attribute, resolve_types from attrs import has as attrs_has from typing_extensions import Self from ._compat import ( ANIES, FrozenSetSubscriptable, Mapping, MutableMapping, MutableSequence, NoneType, OriginAbstractSet, OriginMutableSet, Sequence, Set, TypeAlias, fields, get_final_base, get_newtype_base, get_origin, has, has_with_generic, is_annotated, is_bare, is_counter, is_deque, is_frozenset, is_generic, is_generic_attrs, is_hetero_tuple, is_literal, is_mapping, is_mutable_sequence, is_mutable_set, is_optional, is_protocol, is_tuple, is_typeddict, is_union_type, signature, ) from .cols import ( defaultdict_structure_factory, homogenous_tuple_structure_factory, is_abstract_set, is_defaultdict, is_namedtuple, is_sequence, iterable_unstructure_factory, list_structure_factory, mapping_structure_factory, mapping_unstructure_factory, namedtuple_structure_factory, namedtuple_unstructure_factory, ) from .disambiguators import create_default_dis_func, is_supported_union from .dispatch import ( HookFactory, MultiStrategyDispatch, StructuredValue, StructureHook, TargetType, UnstructuredValue, UnstructureHook, ) from .errors import ( IterableValidationError, IterableValidationNote, StructureHandlerNotFoundError, ) from .fns import Predicate, identity, raise_error from .gen import ( AttributeOverride, HeteroTupleUnstructureFn, IterableUnstructureFn, MappingUnstructureFn, make_dict_structure_fn, make_dict_unstructure_fn, make_hetero_tuple_unstructure_fn, ) from .gen.typeddicts import make_dict_structure_fn as make_typeddict_dict_struct_fn from .gen.typeddicts import make_dict_unstructure_fn as make_typeddict_dict_unstruct_fn from .literals import is_literal_containing_enums from .typealiases import ( get_type_alias_base, is_type_alias, type_alias_structure_factory, ) from .types import SimpleStructureHook __all__ = ["BaseConverter", "Converter", "GenConverter", "UnstructureStrategy"] T = TypeVar("T") V = TypeVar("V") UnstructureHookFactory = TypeVar( "UnstructureHookFactory", bound=HookFactory[UnstructureHook] ) # The Extended factory also takes a converter. ExtendedUnstructureHookFactory: TypeAlias = Callable[[TargetType, T], UnstructureHook] # This typevar for the BaseConverter. AnyUnstructureHookFactoryBase = TypeVar( "AnyUnstructureHookFactoryBase", bound="HookFactory[UnstructureHook] | ExtendedUnstructureHookFactory[BaseConverter]", ) # This typevar for the Converter. AnyUnstructureHookFactory = TypeVar( "AnyUnstructureHookFactory", bound="HookFactory[UnstructureHook] | ExtendedUnstructureHookFactory[Converter]", ) StructureHookFactory = TypeVar("StructureHookFactory", bound=HookFactory[StructureHook]) # The Extended factory also takes a converter. ExtendedStructureHookFactory: TypeAlias = Callable[[TargetType, T], StructureHook] # This typevar for the BaseConverter. AnyStructureHookFactoryBase = TypeVar( "AnyStructureHookFactoryBase", bound="HookFactory[StructureHook] | ExtendedStructureHookFactory[BaseConverter]", ) # This typevar for the Converter. AnyStructureHookFactory = TypeVar( "AnyStructureHookFactory", bound="HookFactory[StructureHook] | ExtendedStructureHookFactory[Converter]", ) UnstructureHookT = TypeVar("UnstructureHookT", bound=UnstructureHook) StructureHookT = TypeVar("StructureHookT", bound=StructureHook) CounterT = TypeVar("CounterT", bound=Counter) class UnstructureStrategy(Enum): """`attrs` classes unstructuring strategies.""" AS_DICT = "asdict" AS_TUPLE = "astuple" def _is_extended_factory(factory: Callable) -> bool: """Does this factory also accept a converter arg?""" # We use the original `inspect.signature` to not evaluate string # annotations. sig = inspect_signature(factory) return ( len(sig.parameters) >= 2 and (list(sig.parameters.values())[1]).default is Signature.empty ) class BaseConverter: """Converts between structured and unstructured data.""" __slots__ = ( "_dict_factory", "_prefer_attrib_converters", "_struct_copy_skip", "_structure_attrs", "_structure_func", "_union_struct_registry", "_unstruct_copy_skip", "_unstructure_attrs", "_unstructure_func", "detailed_validation", ) def __init__( self, dict_factory: Callable[[], Any] = dict, unstruct_strat: UnstructureStrategy = UnstructureStrategy.AS_DICT, prefer_attrib_converters: bool = False, detailed_validation: bool = True, unstructure_fallback_factory: HookFactory[UnstructureHook] = lambda _: identity, structure_fallback_factory: HookFactory[StructureHook] = lambda t: raise_error( None, t ), ) -> None: """ :param detailed_validation: Whether to use a slightly slower mode for detailed validation errors. :param unstructure_fallback_factory: A hook factory to be called when no registered unstructuring hooks match. :param structure_fallback_factory: A hook factory to be called when no registered structuring hooks match. .. versionadded:: 23.2.0 *unstructure_fallback_factory* .. versionadded:: 23.2.0 *structure_fallback_factory* .. versionchanged:: 24.2.0 The default `structure_fallback_factory` now raises errors for missing handlers more eagerly, surfacing problems earlier. """ unstruct_strat = UnstructureStrategy(unstruct_strat) self._prefer_attrib_converters = prefer_attrib_converters self.detailed_validation = detailed_validation self._union_struct_registry: dict[Any, Callable[[Any, type[T]], T]] = {} # Create a per-instance cache. if unstruct_strat is UnstructureStrategy.AS_DICT: self._unstructure_attrs = self.unstructure_attrs_asdict self._structure_attrs = self.structure_attrs_fromdict else: self._unstructure_attrs = self.unstructure_attrs_astuple self._structure_attrs = self.structure_attrs_fromtuple self._unstructure_func = MultiStrategyDispatch( unstructure_fallback_factory, self ) self._unstructure_func.register_cls_list( [(bytes, identity), (str, identity), (Path, str)] ) self._unstructure_func.register_func_list( [ ( lambda t: get_newtype_base(t) is not None, lambda o: self.unstructure(o, unstructure_as=o.__class__), ), ( is_protocol, lambda o: self.unstructure(o, unstructure_as=o.__class__), ), ( lambda t: get_final_base(t) is not None, lambda t: self.get_unstructure_hook(get_final_base(t)), True, ), ( is_type_alias, lambda t: self.get_unstructure_hook(get_type_alias_base(t)), True, ), (is_literal_containing_enums, self.unstructure), (is_mapping, self._unstructure_mapping), (is_sequence, self._unstructure_seq), (is_mutable_set, self._unstructure_seq), (is_frozenset, self._unstructure_seq), (lambda t: issubclass(t, Enum), self._unstructure_enum), (has, self._unstructure_attrs), (is_union_type, self._unstructure_union), (lambda t: t in ANIES, self.unstructure), ] ) # Per-instance register of to-attrs converters. # Singledispatch dispatches based on the first argument, so we # store the function and switch the arguments in self.loads. self._structure_func = MultiStrategyDispatch(structure_fallback_factory, self) self._structure_func.register_func_list( [ ( lambda cl: cl in ANIES or cl is Optional or cl is None, lambda v, _: v, ), (is_generic_attrs, self._gen_structure_generic, True), (lambda t: get_newtype_base(t) is not None, self._structure_newtype), (is_type_alias, type_alias_structure_factory, "extended"), ( lambda t: get_final_base(t) is not None, self._structure_final_factory, True, ), (is_literal, self._structure_simple_literal), (is_literal_containing_enums, self._structure_enum_literal), (is_sequence, homogenous_tuple_structure_factory, "extended"), (is_mutable_sequence, list_structure_factory, "extended"), (is_deque, self._structure_deque), (is_mutable_set, self._structure_set), (is_abstract_set, self._structure_frozenset), (is_frozenset, self._structure_frozenset), (is_tuple, self._structure_tuple), (is_namedtuple, namedtuple_structure_factory, "extended"), (is_mapping, self._structure_dict), *( [(is_supported_union, self._gen_attrs_union_structure, True)] if unstruct_strat is UnstructureStrategy.AS_DICT else [] ), (is_optional, self._structure_optional), ( lambda t: is_union_type(t) and t in self._union_struct_registry, self._union_struct_registry.__getitem__, True, ), (has, self._structure_attrs), ] ) # Strings are sequences. self._structure_func.register_cls_list( [ (str, self._structure_call), (bytes, self._structure_call), (int, self._structure_call), (float, self._structure_call), (Enum, self._structure_call), (Path, self._structure_call), ] ) self._dict_factory = dict_factory self._unstruct_copy_skip = self._unstructure_func.get_num_fns() self._struct_copy_skip = self._structure_func.get_num_fns() def unstructure(self, obj: Any, unstructure_as: Any = None) -> Any: return self._unstructure_func.dispatch( obj.__class__ if unstructure_as is None else unstructure_as )(obj) @property def unstruct_strat(self) -> UnstructureStrategy: """The default way of unstructuring ``attrs`` classes.""" return ( UnstructureStrategy.AS_DICT if self._unstructure_attrs == self.unstructure_attrs_asdict else UnstructureStrategy.AS_TUPLE ) @overload def register_unstructure_hook(self, cls: UnstructureHookT) -> UnstructureHookT: ... @overload def register_unstructure_hook(self, cls: Any, func: UnstructureHook) -> None: ... def register_unstructure_hook( self, cls: Any = None, func: UnstructureHook | None = None ) -> Callable[[UnstructureHook]] | None: """Register a class-to-primitive converter function for a class. The converter function should take an instance of the class and return its Python equivalent. May also be used as a decorator. When used as a decorator, the first argument annotation from the decorated function will be used as the type to register the hook for. .. versionchanged:: 24.1.0 This method may now be used as a decorator. .. versionchanged:: 25.1.0 Modern type aliases are now supported. """ if func is None: # Autodetecting decorator. func = cls sig = signature(func) cls = next(iter(sig.parameters.values())).annotation self.register_unstructure_hook(cls, func) return func if attrs_has(cls): resolve_types(cls) if is_union_type(cls): self._unstructure_func.register_func_list([(lambda t: t == cls, func)]) elif is_type_alias(cls): self._unstructure_func.register_func_list([(lambda t: t is cls, func)]) elif get_newtype_base(cls) is not None: # This is a newtype, so we handle it specially. self._unstructure_func.register_func_list([(lambda t: t is cls, func)]) else: self._unstructure_func.register_cls_list([(cls, func)]) return None def register_unstructure_hook_func( self, check_func: Predicate, func: UnstructureHook ) -> None: """Register a class-to-primitive converter function for a class, using a function to check if it's a match. """ self._unstructure_func.register_func_list([(check_func, func)]) @overload def register_unstructure_hook_factory( self, predicate: Predicate ) -> Callable[[AnyUnstructureHookFactoryBase], AnyUnstructureHookFactoryBase]: ... @overload def register_unstructure_hook_factory( self, predicate: Predicate, factory: UnstructureHookFactory ) -> UnstructureHookFactory: ... @overload def register_unstructure_hook_factory( self, predicate: Predicate, factory: ExtendedUnstructureHookFactory[BaseConverter], ) -> ExtendedUnstructureHookFactory[BaseConverter]: ... def register_unstructure_hook_factory(self, predicate, factory=None): """ Register a hook factory for a given predicate. The hook factory may expose an additional required parameter. In this case, the current converter will be provided to the hook factory as that parameter. May also be used as a decorator. :param predicate: A function that, given a type, returns whether the factory can produce a hook for that type. :param factory: A callable that, given a type, produces an unstructuring hook for that type. This unstructuring hook will be cached. .. versionchanged:: 24.1.0 This method may now be used as a decorator. The factory may also receive the converter as a second, required argument. """ if factory is None: def decorator(factory): # Is this an extended factory (takes a converter too)? if _is_extended_factory(factory): self._unstructure_func.register_func_list( [(predicate, factory, "extended")] ) else: self._unstructure_func.register_func_list( [(predicate, factory, True)] ) return decorator self._unstructure_func.register_func_list( [ ( predicate, factory, "extended" if _is_extended_factory(factory) else True, ) ] ) return factory def get_unstructure_hook( self, type: Any, cache_result: bool = True ) -> UnstructureHook: """Get the unstructure hook for the given type. This hook can be manually called, or composed with other functions and re-registered. If no hook is registered, the converter unstructure fallback factory will be used to produce one. :param cache: Whether to cache the returned hook. .. versionadded:: 24.1.0 """ return ( self._unstructure_func.dispatch(type) if cache_result else self._unstructure_func.dispatch_without_caching(type) ) @overload def register_structure_hook(self, cl: StructureHookT) -> StructureHookT: ... @overload def register_structure_hook(self, cl: Any, func: StructureHook) -> None: ... def register_structure_hook( self, cl: Any, func: StructureHook | None = None ) -> None: """Register a primitive-to-class converter function for a type. The converter function should take two arguments: * a Python object to be converted, * the type to convert to and return the instance of the class. The type may seem redundant, but is sometimes needed (for example, when dealing with generic classes). This method may be used as a decorator. In this case, the decorated hook must have a return type annotation, and this annotation will be used as the type for the hook. .. versionchanged:: 24.1.0 This method may now be used as a decorator. .. versionchanged:: 25.1.0 Modern type aliases are now supported. """ if func is None: # The autodetecting decorator. func = cl sig = signature(func) self.register_structure_hook(sig.return_annotation, func) return func if attrs_has(cl): resolve_types(cl) if is_union_type(cl): self._union_struct_registry[cl] = func self._structure_func.clear_cache() elif is_type_alias(cl): # Type aliases are special-cased. self._structure_func.register_func_list([(lambda t: t is cl, func)]) elif get_newtype_base(cl) is not None: # This is a newtype, so we handle it specially. self._structure_func.register_func_list([(lambda t: t is cl, func)]) else: self._structure_func.register_cls_list([(cl, func)]) return None def register_structure_hook_func( self, check_func: Predicate, func: StructureHook ) -> None: """Register a class-to-primitive converter function for a class, using a function to check if it's a match. """ self._structure_func.register_func_list([(check_func, func)]) @overload def register_structure_hook_factory( self, predicate: Predicate ) -> Callable[[AnyStructureHookFactoryBase], AnyStructureHookFactoryBase]: ... @overload def register_structure_hook_factory( self, predicate: Predicate, factory: StructureHookFactory ) -> StructureHookFactory: ... @overload def register_structure_hook_factory( self, predicate: Predicate, factory: ExtendedStructureHookFactory[BaseConverter] ) -> ExtendedStructureHookFactory[BaseConverter]: ... def register_structure_hook_factory(self, predicate, factory=None): """ Register a hook factory for a given predicate. The hook factory may expose an additional required parameter. In this case, the current converter will be provided to the hook factory as that parameter. May also be used as a decorator. :param predicate: A function that, given a type, returns whether the factory can produce a hook for that type. :param factory: A callable that, given a type, produces a structuring hook for that type. This structuring hook will be cached. .. versionchanged:: 24.1.0 This method may now be used as a decorator. The factory may also receive the converter as a second, required argument. """ if factory is None: # Decorator use. def decorator(factory): # Is this an extended factory (takes a converter too)? if _is_extended_factory(factory): self._structure_func.register_func_list( [(predicate, factory, "extended")] ) else: self._structure_func.register_func_list( [(predicate, factory, True)] ) return decorator self._structure_func.register_func_list( [ ( predicate, factory, "extended" if _is_extended_factory(factory) else True, ) ] ) return factory def structure(self, obj: UnstructuredValue, cl: type[T]) -> T: """Convert unstructured Python data structures to structured data.""" return self._structure_func.dispatch(cl)(obj, cl) def get_structure_hook(self, type: Any, cache_result: bool = True) -> StructureHook: """Get the structure hook for the given type. This hook can be manually called, or composed with other functions and re-registered. If no hook is registered, the converter structure fallback factory will be used to produce one. :param cache: Whether to cache the returned hook. .. versionadded:: 24.1.0 """ return ( self._structure_func.dispatch(type) if cache_result else self._structure_func.dispatch_without_caching(type) ) # Classes to Python primitives. def unstructure_attrs_asdict(self, obj: Any) -> dict[str, Any]: """Our version of `attrs.asdict`, so we can call back to us.""" attrs = fields(obj.__class__) dispatch = self._unstructure_func.dispatch rv = self._dict_factory() for a in attrs: name = a.name v = getattr(obj, name) rv[name] = dispatch(a.type or v.__class__)(v) return rv def unstructure_attrs_astuple(self, obj: Any) -> tuple[Any, ...]: """Our version of `attrs.astuple`, so we can call back to us.""" attrs = fields(obj.__class__) dispatch = self._unstructure_func.dispatch res = [] for a in attrs: name = a.name v = getattr(obj, name) res.append(dispatch(a.type or v.__class__)(v)) return tuple(res) def _unstructure_enum(self, obj: Enum) -> Any: """Convert an enum to its value.""" return obj.value def _unstructure_seq(self, seq: Sequence[T]) -> Sequence[T]: """Convert a sequence to primitive equivalents.""" # We can reuse the sequence class, so tuples stay tuples. dispatch = self._unstructure_func.dispatch return seq.__class__(dispatch(e.__class__)(e) for e in seq) def _unstructure_mapping(self, mapping: Mapping[T, V]) -> Mapping[T, V]: """Convert a mapping of attr classes to primitive equivalents.""" # We can reuse the mapping class, so dicts stay dicts and OrderedDicts # stay OrderedDicts. dispatch = self._unstructure_func.dispatch return mapping.__class__( (dispatch(k.__class__)(k), dispatch(v.__class__)(v)) for k, v in mapping.items() ) # note: Use UnionType when 3.11 is released as # the behaviour of @final is changed. This would # affect how we can support UnionType in ._compat.py def _unstructure_union(self, obj: Any) -> Any: """ Unstructure an object as a union. By default, just unstructures the instance. """ return self._unstructure_func.dispatch(obj.__class__)(obj) # Python primitives to classes. def _gen_structure_generic( self, cl: type[T] ) -> SimpleStructureHook[Mapping[str, Any], T]: """Create and return a hook for structuring generics.""" return make_dict_structure_fn( cl, self, _cattrs_prefer_attrib_converters=self._prefer_attrib_converters ) def _gen_attrs_union_structure( self, cl: Any, use_literals: bool = True ) -> Callable[[Any, type[T]], type[T] | None]: """ Generate a structuring function for a union of attrs classes (and maybe None). :param use_literals: Whether to consider literal fields. """ dis_fn = self._get_dis_func(cl, use_literals=use_literals) has_none = NoneType in cl.__args__ if has_none: def structure_attrs_union(obj, _) -> cl: if obj is None: return None return self.structure(obj, dis_fn(obj)) else: def structure_attrs_union(obj, _): return self.structure(obj, dis_fn(obj)) return structure_attrs_union @staticmethod def _structure_call(obj: Any, cl: type[T]) -> Any: """Just call ``cl`` with the given ``obj``. This is just an optimization on the ``_structure_default`` case, when we know we can skip the ``if`` s. Use for ``str``, ``bytes``, ``enum``, etc. """ return cl(obj) @staticmethod def _structure_simple_literal(val, type): if val not in type.__args__: raise Exception(f"{val} not in literal {type}") return val @staticmethod def _structure_enum_literal(val, type): vals = {(x.value if isinstance(x, Enum) else x): x for x in type.__args__} try: return vals[val] except KeyError: raise Exception(f"{val} not in literal {type}") from None def _structure_newtype(self, val: UnstructuredValue, type) -> StructuredValue: base = get_newtype_base(type) return self.get_structure_hook(base)(val, base) def _structure_final_factory(self, type): base = get_final_base(type) res = self.get_structure_hook(base) return lambda v, _, __base=base: res(v, __base) # Attrs classes. def structure_attrs_fromtuple(self, obj: tuple[Any, ...], cl: type[T]) -> T: """Load an attrs class from a sequence (tuple).""" conv_obj = [] # A list of converter parameters. for a, value in zip(fields(cl), obj): # We detect the type by the metadata. converted = self._structure_attribute(a, value) conv_obj.append(converted) return cl(*conv_obj) def _structure_attribute(self, a: Attribute | Field, value: Any) -> Any: """Handle an individual attrs attribute.""" type_ = a.type attrib_converter = getattr(a, "converter", None) if self._prefer_attrib_converters and attrib_converter: # A attrib converter is defined on this attribute, and # prefer_attrib_converters is set to give these priority over registered # structure hooks. So, pass through the raw value, which attrs will flow # into the converter return value if type_ is None: # No type metadata. return value try: return self._structure_func.dispatch(type_)(value, type_) except StructureHandlerNotFoundError: if attrib_converter: # Return the original value and fallback to using an attrib converter. return value raise def structure_attrs_fromdict(self, obj: Mapping[str, Any], cl: type[T]) -> T: """Instantiate an attrs class from a mapping (dict).""" # For public use. conv_obj = {} # Start with a fresh dict, to ignore extra keys. for a in fields(cl): try: val = obj[a.name] except KeyError: continue # try .alias and .name because this code also supports dataclasses! conv_obj[getattr(a, "alias", a.name)] = self._structure_attribute(a, val) return cl(**conv_obj) def _structure_deque(self, obj: Iterable[T], cl: Any) -> deque[T]: """Convert an iterable to a potentially generic deque.""" if is_bare(cl) or cl.__args__[0] in ANIES: res = deque(obj) else: elem_type = cl.__args__[0] handler = self._structure_func.dispatch(elem_type) if self.detailed_validation: errors = [] res = deque() ix = 0 # Avoid `enumerate` for performance. for e in obj: try: res.append(handler(e, elem_type)) except Exception as e: msg = IterableValidationNote( f"Structuring {cl} @ index {ix}", ix, elem_type ) e.__notes__ = [*getattr(e, "__notes__", []), msg] errors.append(e) finally: ix += 1 if errors: raise IterableValidationError( f"While structuring {cl!r}", errors, cl ) else: res = deque(handler(e, elem_type) for e in obj) return res def _structure_set( self, obj: Iterable[T], cl: Any, structure_to: type = set ) -> Set[T]: """Convert an iterable into a potentially generic set.""" if is_bare(cl) or cl.__args__[0] in ANIES: return structure_to(obj) elem_type = cl.__args__[0] handler = self._structure_func.dispatch(elem_type) if self.detailed_validation: errors = [] res = set() ix = 0 for e in obj: try: res.add(handler(e, elem_type)) except Exception as exc: msg = IterableValidationNote( f"Structuring {structure_to.__name__} @ element {e!r}", ix, elem_type, ) exc.__notes__ = [*getattr(exc, "__notes__", []), msg] errors.append(exc) finally: ix += 1 if errors: raise IterableValidationError(f"While structuring {cl!r}", errors, cl) return res if structure_to is set else structure_to(res) if structure_to is set: return {handler(e, elem_type) for e in obj} return structure_to([handler(e, elem_type) for e in obj]) def _structure_frozenset( self, obj: Iterable[T], cl: Any ) -> FrozenSetSubscriptable[T]: """Convert an iterable into a potentially generic frozenset.""" return self._structure_set(obj, cl, structure_to=frozenset) def _structure_dict(self, obj: Mapping[T, V], cl: Any) -> dict[T, V]: """Convert a mapping into a potentially generic dict.""" if is_bare(cl) or cl.__args__ == (Any, Any): return dict(obj) key_type, val_type = cl.__args__ if self.detailed_validation: key_handler = self._structure_func.dispatch(key_type) val_handler = self._structure_func.dispatch(val_type) errors = [] res = {} for k, v in obj.items(): try: value = val_handler(v, val_type) except Exception as exc: msg = IterableValidationNote( f"Structuring mapping value @ key {k!r}", k, val_type ) exc.__notes__ = [*getattr(exc, "__notes__", []), msg] errors.append(exc) continue try: key = key_handler(k, key_type) res[key] = value except Exception as exc: msg = IterableValidationNote( f"Structuring mapping key @ key {k!r}", k, key_type ) exc.__notes__ = [*getattr(exc, "__notes__", []), msg] errors.append(exc) if errors: raise IterableValidationError(f"While structuring {cl!r}", errors, cl) return res if key_type in ANIES: val_conv = self._structure_func.dispatch(val_type) return {k: val_conv(v, val_type) for k, v in obj.items()} if val_type in ANIES: key_conv = self._structure_func.dispatch(key_type) return {key_conv(k, key_type): v for k, v in obj.items()} key_conv = self._structure_func.dispatch(key_type) val_conv = self._structure_func.dispatch(val_type) return {key_conv(k, key_type): val_conv(v, val_type) for k, v in obj.items()} def _structure_optional(self, obj, union): if obj is None: return None union_params = union.__args__ other = union_params[0] if union_params[1] is NoneType else union_params[1] # We can't actually have a Union of a Union, so this is safe. return self._structure_func.dispatch(other)(obj, other) def _structure_tuple(self, obj: Iterable, tup: type[T]) -> T: """Deal with structuring into a tuple.""" tup_params = None if tup in (Tuple, tuple) else tup.__args__ has_ellipsis = tup_params and tup_params[-1] is Ellipsis if tup_params is None or (has_ellipsis and tup_params[0] in ANIES): # Just a Tuple. (No generic information.) return tuple(obj) if has_ellipsis: # We're dealing with a homogenous tuple, tuple[int, ...] tup_type = tup_params[0] conv = self._structure_func.dispatch(tup_type) if self.detailed_validation: errors = [] res = [] ix = 0 for e in obj: try: res.append(conv(e, tup_type)) except Exception as exc: msg = IterableValidationNote( f"Structuring {tup} @ index {ix}", ix, tup_type ) exc.__notes__ = [*getattr(exc, "__notes__", []), msg] errors.append(exc) finally: ix += 1 if errors: raise IterableValidationError( f"While structuring {tup!r}", errors, tup ) return tuple(res) return tuple(conv(e, tup_type) for e in obj) # We're dealing with a heterogenous tuple. exp_len = len(tup_params) if self.detailed_validation: errors = [] res = [] for ix, (t, e) in enumerate(zip(tup_params, obj)): try: conv = self._structure_func.dispatch(t) res.append(conv(e, t)) except Exception as exc: msg = IterableValidationNote( f"Structuring {tup} @ index {ix}", ix, t ) exc.__notes__ = [*getattr(exc, "__notes__", []), msg] errors.append(exc) if len(obj) != exp_len: problem = "Not enough" if len(res) < exp_len else "Too many" exc = ValueError(f"{problem} values in {obj!r} to structure as {tup!r}") msg = f"Structuring {tup}" exc.__notes__ = [*getattr(exc, "__notes__", []), msg] errors.append(exc) if errors: raise IterableValidationError(f"While structuring {tup!r}", errors, tup) return tuple(res) if len(obj) != exp_len: problem = "Not enough" if len(obj) < len(tup_params) else "Too many" raise ValueError(f"{problem} values in {obj!r} to structure as {tup!r}") return tuple( [self._structure_func.dispatch(t)(e, t) for t, e in zip(tup_params, obj)] ) def _get_dis_func( self, union: Any, use_literals: bool = True, overrides: dict[str, AttributeOverride] | None = None, ) -> Callable[[Any], type]: """Fetch or try creating a disambiguation function for a union.""" union_types = union.__args__ if NoneType in union_types: # We support unions of attrs classes and NoneType higher in the # logic. union_types = tuple(e for e in union_types if e is not NoneType) if not all(has(get_origin(e) or e) for e in union_types): raise StructureHandlerNotFoundError( "Only unions of attrs classes and dataclasses supported " "currently. Register a structure hook manually.", type_=union, ) return create_default_dis_func( self, *union_types, use_literals=use_literals, overrides=overrides if overrides is not None else "from_converter", ) def __deepcopy__(self, _) -> BaseConverter: return self.copy() def copy( self, dict_factory: Callable[[], Any] | None = None, unstruct_strat: UnstructureStrategy | None = None, prefer_attrib_converters: bool | None = None, detailed_validation: bool | None = None, ) -> Self: """Create a copy of the converter, keeping all existing custom hooks. :param detailed_validation: Whether to use a slightly slower mode for detailed validation errors. """ res = self.__class__( dict_factory if dict_factory is not None else self._dict_factory, ( unstruct_strat if unstruct_strat is not None else ( UnstructureStrategy.AS_DICT if self._unstructure_attrs == self.unstructure_attrs_asdict else UnstructureStrategy.AS_TUPLE ) ), ( prefer_attrib_converters if prefer_attrib_converters is not None else self._prefer_attrib_converters ), ( detailed_validation if detailed_validation is not None else self.detailed_validation ), ) self._unstructure_func.copy_to(res._unstructure_func, self._unstruct_copy_skip) self._structure_func.copy_to(res._structure_func, self._struct_copy_skip) return res class Converter(BaseConverter): """A converter which generates specialized un/structuring functions.""" __slots__ = ( "_unstruct_collection_overrides", "forbid_extra_keys", "omit_if_default", "type_overrides", "use_alias", ) def __init__( self, dict_factory: Callable[[], Any] = dict, unstruct_strat: UnstructureStrategy = UnstructureStrategy.AS_DICT, omit_if_default: bool = False, forbid_extra_keys: bool = False, type_overrides: Mapping[type, AttributeOverride] = {}, unstruct_collection_overrides: Mapping[type, UnstructureHook] = {}, prefer_attrib_converters: bool = False, detailed_validation: bool = True, unstructure_fallback_factory: HookFactory[UnstructureHook] = lambda _: identity, structure_fallback_factory: HookFactory[StructureHook] = lambda t: raise_error( None, t ), use_alias: bool = False, ): """ :param detailed_validation: Whether to use a slightly slower mode for detailed validation errors. :param unstructure_fallback_factory: A hook factory to be called when no registered unstructuring hooks match. :param structure_fallback_factory: A hook factory to be called when no registered structuring hooks match. :param use_alias: Whether to use the field alias instead of the field name as the un/structured dictionary key by default. .. versionadded:: 23.2.0 *unstructure_fallback_factory* .. versionadded:: 23.2.0 *structure_fallback_factory* .. versionchanged:: 24.2.0 The default `structure_fallback_factory` now raises errors for missing handlers more eagerly, surfacing problems earlier. .. versionadded:: 25.2.0 *use_alias* """ super().__init__( dict_factory=dict_factory, unstruct_strat=unstruct_strat, prefer_attrib_converters=prefer_attrib_converters, detailed_validation=detailed_validation, unstructure_fallback_factory=unstructure_fallback_factory, structure_fallback_factory=structure_fallback_factory, ) self.omit_if_default = omit_if_default self.forbid_extra_keys = forbid_extra_keys self.type_overrides = dict(type_overrides) self.use_alias = use_alias unstruct_collection_overrides = { get_origin(k) or k: v for k, v in unstruct_collection_overrides.items() } self._unstruct_collection_overrides = unstruct_collection_overrides # Do a little post-processing magic to make things easier for users. co = unstruct_collection_overrides # abc.Set overrides, if defined, apply to abc.MutableSets and sets if OriginAbstractSet in co: if OriginMutableSet not in co: co[OriginMutableSet] = co[OriginAbstractSet] if FrozenSetSubscriptable not in co: co[FrozenSetSubscriptable] = co[OriginAbstractSet] # abc.MutableSet overrrides, if defined, apply to sets if OriginMutableSet in co and set not in co: co[set] = co[OriginMutableSet] # abc.Sequence overrides, if defined, can apply to MutableSequences, lists and # tuples if Sequence in co: if MutableSequence not in co: co[MutableSequence] = co[Sequence] if tuple not in co: co[tuple] = co[Sequence] # abc.MutableSequence overrides, if defined, can apply to lists if MutableSequence in co: if list not in co: co[list] = co[MutableSequence] if deque not in co: co[deque] = co[MutableSequence] # abc.Mapping overrides, if defined, can apply to MutableMappings if Mapping in co and MutableMapping not in co: co[MutableMapping] = co[Mapping] # abc.MutableMapping overrides, if defined, can apply to dicts if MutableMapping in co and dict not in co: co[dict] = co[MutableMapping] # builtins.dict overrides, if defined, can apply to counters if dict in co and Counter not in co: co[Counter] = co[dict] if unstruct_strat is UnstructureStrategy.AS_DICT: # Override the attrs handler. self.register_unstructure_hook_factory( has_with_generic, self.gen_unstructure_attrs_fromdict ) self.register_structure_hook_factory( has_with_generic, self.gen_structure_attrs_fromdict ) self.register_unstructure_hook_factory( is_annotated, self.gen_unstructure_annotated ) self.register_unstructure_hook_factory( is_hetero_tuple, self.gen_unstructure_hetero_tuple ) self.register_unstructure_hook_factory(is_namedtuple)( namedtuple_unstructure_factory ) self.register_unstructure_hook_factory( is_sequence, self.gen_unstructure_iterable ) self.register_unstructure_hook_factory(is_mapping, self.gen_unstructure_mapping) self.register_unstructure_hook_factory( is_mutable_set, lambda cl: self.gen_unstructure_iterable(cl, unstructure_to=set), ) self.register_unstructure_hook_factory( is_frozenset, lambda cl: self.gen_unstructure_iterable(cl, unstructure_to=frozenset), ) self.register_unstructure_hook_factory( is_optional, self.gen_unstructure_optional ) self.register_unstructure_hook_factory( is_typeddict, self.gen_unstructure_typeddict ) self.register_unstructure_hook_factory( lambda t: get_newtype_base(t) is not None, lambda t: self.get_unstructure_hook(get_newtype_base(t)), ) self.register_structure_hook_factory(is_annotated, self.gen_structure_annotated) self.register_structure_hook_factory(is_mapping, self.gen_structure_mapping) self.register_structure_hook_factory(is_counter, self.gen_structure_counter) self.register_structure_hook_factory( is_defaultdict, defaultdict_structure_factory ) self.register_structure_hook_factory(is_typeddict, self.gen_structure_typeddict) self.register_structure_hook_factory( lambda t: get_newtype_base(t) is not None, self.get_structure_newtype ) # We keep these so we can more correctly copy the hooks. self._struct_copy_skip = self._structure_func.get_num_fns() self._unstruct_copy_skip = self._unstructure_func.get_num_fns() @overload def register_unstructure_hook_factory( self, predicate: Predicate ) -> Callable[[AnyUnstructureHookFactory], AnyUnstructureHookFactory]: ... @overload def register_unstructure_hook_factory( self, predicate: Predicate, factory: UnstructureHookFactory ) -> UnstructureHookFactory: ... @overload def register_unstructure_hook_factory( self, predicate: Predicate, factory: ExtendedUnstructureHookFactory[Converter] ) -> ExtendedUnstructureHookFactory[Converter]: ... def register_unstructure_hook_factory(self, predicate, factory=None): # This dummy wrapper is required due to how `@overload` works. return super().register_unstructure_hook_factory(predicate, factory) @overload def register_structure_hook_factory( self, predicate: Predicate ) -> Callable[[AnyStructureHookFactory], AnyStructureHookFactory]: ... @overload def register_structure_hook_factory( self, predicate: Predicate, factory: StructureHookFactory ) -> StructureHookFactory: ... @overload def register_structure_hook_factory( self, predicate: Predicate, factory: ExtendedStructureHookFactory[Converter] ) -> ExtendedStructureHookFactory[Converter]: ... def register_structure_hook_factory(self, predicate, factory=None): # This dummy wrapper is required due to how `@overload` works. return super().register_structure_hook_factory(predicate, factory) def get_structure_newtype(self, type: type[T]) -> Callable[[Any, Any], T]: base = get_newtype_base(type) handler = self.get_structure_hook(base) return lambda v, _: handler(v, base) def gen_unstructure_annotated(self, type): origin = type.__origin__ return self.get_unstructure_hook(origin) def gen_structure_annotated(self, type) -> Callable: """A hook factory for annotated types.""" origin = type.__origin__ hook = self.get_structure_hook(origin) return lambda v, _: hook(v, origin) def gen_unstructure_typeddict(self, cl: Any) -> Callable[[dict], dict]: """Generate a TypedDict unstructure function. Also apply converter-scored modifications. """ return make_typeddict_dict_unstruct_fn(cl, self) def gen_unstructure_attrs_fromdict( self, cl: type[T] ) -> Callable[[T], dict[str, Any]]: origin = get_origin(cl) attribs = fields(origin or cl) if attrs_has(cl) and any(isinstance(a.type, str) for a in attribs): # PEP 563 annotations - need to be resolved. resolve_types(origin or cl) attrib_overrides = { a.name: self.type_overrides[a.type] for a in attribs if a.type in self.type_overrides } return make_dict_unstructure_fn( cl, self, _cattrs_omit_if_default=self.omit_if_default, **attrib_overrides ) def gen_unstructure_optional(self, cl: type[T]) -> Callable[[T], Any]: """Generate an unstructuring hook for optional types.""" union_params = cl.__args__ other = union_params[0] if union_params[1] is NoneType else union_params[1] if isinstance(other, TypeVar): handler = self.unstructure else: handler = self.get_unstructure_hook(other) def unstructure_optional(val, _handler=handler): return None if val is None else _handler(val) return unstructure_optional def gen_structure_typeddict(self, cl: Any) -> Callable[[dict, Any], dict]: """Generate a TypedDict structure function. Also apply converter-scored modifications. """ return make_typeddict_dict_struct_fn( cl, self, _cattrs_detailed_validation=self.detailed_validation ) def gen_structure_attrs_fromdict( self, cl: type[T] ) -> Callable[[Mapping[str, Any], Any], T]: attribs = fields(get_origin(cl) or cl if is_generic(cl) else cl) if attrs_has(cl) and any(isinstance(a.type, str) for a in attribs): # PEP 563 annotations - need to be resolved. resolve_types(cl) attrib_overrides = { a.name: self.type_overrides[a.type] for a in attribs if a.type in self.type_overrides } return make_dict_structure_fn( cl, self, _cattrs_forbid_extra_keys=self.forbid_extra_keys, _cattrs_prefer_attrib_converters=self._prefer_attrib_converters, _cattrs_detailed_validation=self.detailed_validation, _cattrs_use_alias=self.use_alias, **attrib_overrides, ) def gen_unstructure_iterable( self, cl: Any, unstructure_to: Any = None ) -> IterableUnstructureFn: unstructure_to = self._unstruct_collection_overrides.get( get_origin(cl) or cl, unstructure_to or list ) h = iterable_unstructure_factory(cl, self, unstructure_to=unstructure_to) self._unstructure_func.register_cls_list([(cl, h)], direct=True) return h def gen_unstructure_hetero_tuple( self, cl: Any, unstructure_to: Any = None ) -> HeteroTupleUnstructureFn: unstructure_to = self._unstruct_collection_overrides.get( get_origin(cl) or cl, unstructure_to or tuple ) h = make_hetero_tuple_unstructure_fn(cl, self, unstructure_to=unstructure_to) self._unstructure_func.register_cls_list([(cl, h)], direct=True) return h def gen_unstructure_mapping( self, cl: Any, unstructure_to: Any = None, key_handler: Callable[[Any, Any | None], Any] | None = None, ) -> MappingUnstructureFn: unstructure_to = self._unstruct_collection_overrides.get( get_origin(cl) or cl, unstructure_to or dict ) h = mapping_unstructure_factory( cl, self, unstructure_to=unstructure_to, key_handler=key_handler ) self._unstructure_func.register_cls_list([(cl, h)], direct=True) return h def gen_structure_counter( self, cl: type[CounterT] ) -> SimpleStructureHook[Mapping[Any, Any], CounterT]: h = mapping_structure_factory( cl, self, structure_to=Counter, val_type=int, detailed_validation=self.detailed_validation, ) self._structure_func.register_cls_list([(cl, h)], direct=True) return h def gen_structure_mapping( self, cl: Any ) -> SimpleStructureHook[Mapping[Any, Any], Any]: structure_to = get_origin(cl) or cl if structure_to in ( MutableMapping, AbcMutableMapping, Mapping, AbcMapping, ): # These default to dicts structure_to = dict h = mapping_structure_factory( cl, self, structure_to, detailed_validation=self.detailed_validation ) self._structure_func.register_cls_list([(cl, h)], direct=True) return h def copy( self, dict_factory: Callable[[], Any] | None = None, unstruct_strat: UnstructureStrategy | None = None, omit_if_default: bool | None = None, forbid_extra_keys: bool | None = None, type_overrides: Mapping[type, AttributeOverride] | None = None, unstruct_collection_overrides: Mapping[type, UnstructureHook] | None = None, prefer_attrib_converters: bool | None = None, detailed_validation: bool | None = None, use_alias: bool | None = None, ) -> Self: """Create a copy of the converter, keeping all existing custom hooks. :param detailed_validation: Whether to use a slightly slower mode for detailed validation errors. """ res = self.__class__( dict_factory if dict_factory is not None else self._dict_factory, ( unstruct_strat if unstruct_strat is not None else ( UnstructureStrategy.AS_DICT if self._unstructure_attrs == self.unstructure_attrs_asdict else UnstructureStrategy.AS_TUPLE ) ), omit_if_default if omit_if_default is not None else self.omit_if_default, ( forbid_extra_keys if forbid_extra_keys is not None else self.forbid_extra_keys ), type_overrides if type_overrides is not None else self.type_overrides, ( unstruct_collection_overrides if unstruct_collection_overrides is not None else self._unstruct_collection_overrides ), ( prefer_attrib_converters if prefer_attrib_converters is not None else self._prefer_attrib_converters ), ( detailed_validation if detailed_validation is not None else self.detailed_validation ), use_alias=(use_alias if use_alias is not None else self.use_alias), ) self._unstructure_func.copy_to( res._unstructure_func, skip=self._unstruct_copy_skip ) self._structure_func.copy_to(res._structure_func, skip=self._struct_copy_skip) return res GenConverter: TypeAlias = Converter