Source code for betty.serde.load

"""
Provide a deserialization API.
"""

from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path
from typing import (
    Iterator,
    Callable,
    Any,
    Generic,
    TYPE_CHECKING,
    TypeVar,
    MutableSequence,
    MutableMapping,
    overload,
    cast,
    TypeAlias,
)

from typing_extensions import override

from betty.functools import _Result
from betty.locale import LocaleNotFoundError, get_data, Str
from betty.model import (
    Entity,
    get_entity_type,
    EntityTypeImportError,
    EntityTypeInvalidError,
    EntityTypeError,
)
from betty.serde.dump import DumpType, DumpTypeT, Void
from betty.serde.error import SerdeError, SerdeErrorCollection

if TYPE_CHECKING:
    from betty.app.extension import Extension

T = TypeVar("T")
ValueT = TypeVar("ValueT")
ReturnT = TypeVar("ReturnT")
ReturnU = TypeVar("ReturnU")
CallValueT = TypeVar("CallValueT")
CallReturnT = TypeVar("CallReturnT")
FValueT = TypeVar("FValueT")
MapReturnT = TypeVar("MapReturnT")
Number: TypeAlias = int | float
NumberT = TypeVar("NumberT", bound=Number)


[docs] class LoadError(SerdeError): """ Raised for any error while deserializing data. """ pass # pragma: no cover
[docs] class AssertionFailed(LoadError): """ Raised when an assertion failed while deserializing data. """ pass # pragma: no cover
[docs] class FormatError(LoadError): """ Raised when data that is being deserialized is provided in an unknown (undeserializable) format. """ pass # pragma: no cover
Assertion: TypeAlias = Callable[ [ ValueT, ], ReturnT, ] class _Assertions(Generic[CallValueT, CallReturnT, FValueT]): def __init__(self, _assertion: Assertion[FValueT, CallReturnT]): self._assertion = _assertion def extend( self, _assertion: Assertion[CallReturnT, MapReturnT] ) -> _Assertions[CallValueT, MapReturnT, CallReturnT]: return _AssertionExtension(_assertion, self) def __or__( self, _assertion: Assertion[CallReturnT, MapReturnT] ) -> _Assertions[CallValueT, MapReturnT, CallReturnT]: return self.extend(_assertion) def __call__(self, value: CallValueT) -> _Result[CallReturnT]: raise NotImplementedError(repr(self))
[docs] class Assertions( _Assertions[CallValueT, CallReturnT, CallValueT], Generic[CallValueT, CallReturnT] ): """ Start an assertions chain. Assertion chains let you chain/link/combine assertions into pipelines that take an input value and, if the assertions pass, return an output value. Each chain may be (re)used as many times as needed. Assertions chains are `monads <https://en.wikipedia.org/wiki/Monad_(functional_programming)>`_. While uncommon in Python, this allows us to create these chains in a type-safe way, and tools like mypy can confirm that all assertions in any given chain are compatible with each other. """ @override def __call__(self, value: CallValueT) -> _Result[CallReturnT]: return _Result(value).map(self._assertion)
class _AssertionExtension( _Assertions[CallValueT, CallReturnT, FValueT], Generic[CallValueT, CallReturnT, FValueT], ): def __init__( self, _assertion: Assertion[FValueT, CallReturnT], extended_assertion: _Assertions[CallValueT, FValueT, Any], ): super().__init__(_assertion) self._extended_assertion = extended_assertion @override def __call__(self, value: CallValueT) -> _Result[CallReturnT]: return self._extended_assertion(value).map(self._assertion) @dataclass(frozen=True) class _Field(Generic[ValueT, ReturnT]): name: str assertion: _Assertions[ValueT, ReturnT, Any] | None = None
[docs] @dataclass(frozen=True) class RequiredField(Generic[ValueT, ReturnT], _Field[ValueT, ReturnT]): """ A required key-value mapping field. """ pass # pragma: no cover
[docs] @dataclass(frozen=True) class OptionalField(Generic[ValueT, ReturnT], _Field[ValueT, ReturnT]): """ An optional key-value mapping field. """ pass # pragma: no cover
[docs] class Fields: """ A sequence of fields, used to assert key-value mappings. """
[docs] def __init__(self, *fields: _Field[Any, Any]): self._fields = fields
def __iter__(self) -> Iterator[_Field[Any, Any]]: return (field for field in self._fields)
_AssertionBuilderFunction = Callable[[ValueT], ReturnT] _AssertionBuilderMethod = Callable[[object, ValueT], ReturnT] _AssertionBuilder = "_AssertionBuilderFunction[ValueT, ReturnT] | _AssertionBuilderMethod[ValueT, ReturnT]"
[docs] class Asserter: """ Provide deserialization assertions. """ def _assert_type_violation_error_message( self, asserted_type: type[DumpType], ) -> Str: messages = { None: Str._("This must be none/null."), bool: Str._("This must be a boolean."), int: Str._("This must be a whole number."), float: Str._("This must be a decimal number."), str: Str._("This must be a string."), list: Str._("This must be a list."), dict: Str._("This must be a key-value mapping."), } return messages[asserted_type] # type: ignore[index] def _assert_type( self, value: Any, value_required_type: type[DumpTypeT], value_disallowed_type: type[DumpType] | None = None, ) -> DumpTypeT: if isinstance(value, value_required_type) and ( value_disallowed_type is None or not isinstance(value, value_disallowed_type) ): return value raise AssertionFailed( self._assert_type_violation_error_message( value_required_type, # type: ignore[arg-type] ) )
[docs] def assert_or( self, if_assertion: Assertion[ValueT, ReturnT], else_assertions: Assertion[ValueT, ReturnU], ) -> Assertion[ValueT, ReturnT | ReturnU]: """ Assert that at least one of the given assertions passed. """ def _assert_or(value: Any) -> ReturnT | ReturnU: assertions = (if_assertion, else_assertions) errors = SerdeErrorCollection() for assertion in assertions: try: return assertion(value) except SerdeError as e: if e.raised(AssertionFailed): errors.append(e) raise errors return _assert_or
[docs] def assert_none(self) -> Assertion[Any, None]: """ Assert that a value is ``None``. """ def _assert_none(value: Any) -> None: self._assert_type(value, type(None)) return _assert_none
[docs] def assert_bool(self) -> Assertion[Any, bool]: """ Assert that a value is a Python ``bool``. """ def _assert_bool(value: Any) -> bool: return self._assert_type(value, bool) return _assert_bool
[docs] def assert_int(self) -> Assertion[Any, int]: """ Assert that a value is a Python ``int``. """ def _assert_int(value: Any) -> int: return self._assert_type(value, int, bool) return _assert_int
[docs] def assert_float(self) -> Assertion[Any, float]: """ Assert that a value is a Python ``float``. """ def _assert_float(value: Any) -> float: return self._assert_type(value, float) return _assert_float
[docs] def assert_number(self) -> Assertion[Any, Number]: """ Assert that a value is a number (a Python ``int`` or ``float``). """ return self.assert_or(self.assert_int(), self.assert_float())
[docs] def assert_positive_number(self) -> Assertion[Any, Number]: """ Assert that a vaue is a positive nu,ber. """ def _assert_positive_number( value: Any, ) -> Number: value = self.assert_number()(value) if value <= 0: raise AssertionFailed(Str._("This must be a positive number.")) return value return _assert_positive_number
[docs] def assert_str(self) -> Assertion[Any, str]: """ Assert that a value is a Python ``str``. """ def _assert_str(value: Any) -> str: return self._assert_type(value, str) return _assert_str
[docs] def assert_list(self) -> Assertion[Any, list[Any]]: """ Assert that a value is a Python ``list``. """ def _assert_list(value: Any) -> list[Any]: return self._assert_type(value, list) return _assert_list
[docs] def assert_dict(self) -> Assertion[Any, dict[str, Any]]: """ Assert that a value is a Python ``dict``. """ def _assert_dict(value: Any) -> dict[str, Any]: return self._assert_type(value, dict) return _assert_dict
[docs] def assert_assertions( self, assertions: _Assertions[ValueT, ReturnT, Any] ) -> Assertion[Any, ReturnT]: """ Assert that an assertions chain passes, and return the chain's output. """ def _assert_assertions(value: Any) -> ReturnT: return assertions(value).value return _assert_assertions
[docs] def assert_sequence( self, item_assertion: Assertions[ValueT, ReturnT] ) -> Assertion[Any, MutableSequence[ReturnT]]: """ Assert that a value is a sequence and that all item values are of the given type. """ def _assert_sequence(value: ValueT) -> MutableSequence[ReturnT]: list_value = self.assert_list()(value) sequence = [] with SerdeErrorCollection().assert_valid() as errors: for value_item_index, value_item_value in enumerate(list_value): with errors.catch(Str.plain(value_item_index)): sequence.append( self.assert_assertions(item_assertion)(value_item_value) ) return sequence return _assert_sequence
[docs] def assert_mapping( self, item_assertion: Assertions[ValueT, ReturnT] ) -> Assertion[Any, MutableMapping[str, ReturnT]]: """ Assert that a value is a key-value mapping and assert that all item values are of the given type. """ def _assert_mapping(value: ValueT) -> MutableMapping[str, ReturnT]: dict_value = self.assert_dict()(value) mapping = {} with SerdeErrorCollection().assert_valid() as errors: for value_item_key, value_item_value in dict_value.items(): with errors.catch(Str.plain(value_item_key)): mapping[value_item_key] = self.assert_assertions( item_assertion )(value_item_value) return mapping return _assert_mapping
[docs] def assert_fields(self, fields: Fields) -> Assertion[Any, MutableMapping[str, Any]]: """ Assert that a value is a key-value mapping of arbitrary value types, and assert several of its values. """ def _assert_fields(value: Any) -> MutableMapping[str, Any]: value_dict = self.assert_dict()(value) mapping = {} with SerdeErrorCollection().assert_valid() as errors: for field in fields: with errors.catch(Str.plain(field.name)): if field.name in value_dict: if field.assertion: mapping[field.name] = self.assert_assertions( field.assertion )(value_dict[field.name]) elif isinstance(field, RequiredField): raise AssertionFailed(Str._("This field is required.")) return mapping return _assert_fields
@overload def assert_field( self, field: RequiredField[ValueT, ReturnT] ) -> Assertion[ValueT, ReturnT]: pass # pragma: no cover @overload def assert_field( self, field: OptionalField[ValueT, ReturnT] ) -> Assertion[ValueT, ReturnT | type[Void]]: pass # pragma: no cover
[docs] def assert_field( self, field: _Field[ValueT, ReturnT] ) -> Assertion[ValueT, ReturnT | type[Void]]: """ Assert that a value is a key-value mapping of arbitrary value types, and assert a single of its values. """ def _assert_field(value: Any) -> ReturnT | type[Void]: fields = self.assert_fields(Fields(field))(value) try: return cast("ReturnT | type[Void]", fields[field.name]) except KeyError: if isinstance(field, RequiredField): raise return Void return _assert_field
[docs] def assert_record(self, fields: Fields) -> Assertion[Any, MutableMapping[str, Any]]: """ Assert that a value is a record: a key-value mapping of arbitrary value types, with a known structure. To validate a key-value mapping as a records, assertions for all possible keys MUST be provided. Any keys present in the value for which no field assertions are provided will cause the entire record assertion to fail. """ if not len(list(fields)): raise ValueError("One or more fields are required.") def _assert_record(value: Any) -> MutableMapping[str, Any]: dict_value = self.assert_dict()(value) known_keys = {x.name for x in fields} unknown_keys = set(dict_value.keys()) - known_keys with SerdeErrorCollection().assert_valid() as errors: for unknown_key in unknown_keys: with errors.catch(Str.plain(unknown_key)): raise AssertionFailed( Str._( "Unknown key: {unknown_key}. Did you mean {known_keys}?", unknown_key=f'"{unknown_key}"', known_keys=", ".join( (f'"{x}"' for x in sorted(known_keys)) ), ) ) return self.assert_fields(fields)(dict_value) return _assert_record
[docs] def assert_path(self) -> Assertion[Any, Path]: """ Assert that a value is a path to a file or directory on disk that may or may not exist. """ def _assert_path(value: Any) -> Path: self.assert_str()(value) return Path(value).expanduser().resolve() return _assert_path
[docs] def assert_directory_path(self) -> Assertion[Any, Path]: """ Assert that a value is a path to an existing directory. """ def _assert_directory_path(value: Any) -> Path: directory_path = self.assert_path()(value) if directory_path.is_dir(): return directory_path raise AssertionFailed( Str._( '"{path}" is not a directory.', path=value, ) ) return _assert_directory_path
[docs] def assert_locale(self) -> Assertion[Any, str]: """ Assert that a value is a valid `IETF BCP 47 language tag <https://en.wikipedia.org/wiki/IETF_language_tag>`_. """ def _assert_locale( value: Any, ) -> str: value = self.assert_str()(value) try: get_data(value) return value except LocaleNotFoundError: raise AssertionFailed( Str._( '"{locale}" is not a valid IETF BCP 47 language tag.', locale=value, ) ) from None return _assert_locale
[docs] def assert_setattr( self, instance: object, attr_name: str ) -> Assertion[ValueT, ValueT]: """ Set a value for the given object's attribute. """ def _assert_setattr(value: ValueT) -> ValueT: setattr(instance, attr_name, value) return value return _assert_setattr
[docs] def assert_extension_type(self) -> Assertion[Any, type[Extension]]: """ Assert that a value is an extension type. This assertion passes if the value is fully qualified :py:class:`betty.app.extension.Extension` subclass name. """ def _assert_extension_type( value: Any, ) -> type[Extension]: from betty.app.extension import ( get_extension_type, ExtensionTypeImportError, ExtensionTypeInvalidError, ExtensionTypeError, ) self.assert_str()(value) try: return get_extension_type(value) except ExtensionTypeImportError: raise AssertionFailed( Str._( 'Cannot find and import "{extension_type}".', extension_type=str(value), ) ) from None except ExtensionTypeInvalidError: raise AssertionFailed( Str._( '"{extension_type}" is not a valid Betty extension type.', extension_type=str(value), ) ) from None except ExtensionTypeError: raise AssertionFailed( Str._( 'Cannot determine the extension type for "{extension_type}". Did you perhaps make a typo, or could it be that the extension type comes from another package that is not yet installed?', extension_type=str(value), ) ) from None return _assert_extension_type
[docs] def assert_entity_type(self) -> Assertion[Any, type[Entity]]: """ Assert that a value is an entity type. This assertion passes if the value is fully qualified :py:class:`betty.model.Entity` subclass name. """ def _assert_entity_type( value: Any, ) -> type[Entity]: self.assert_str()(value) try: return get_entity_type(value) except EntityTypeImportError: raise AssertionFailed( Str._( 'Cannot find and import "{entity_type}".', entity_type=str(value), ) ) from None except EntityTypeInvalidError: raise AssertionFailed( Str._( '"{entity_type}" is not a valid Betty entity type.', entity_type=str(value), ) ) from None except EntityTypeError: raise AssertionFailed( Str._( 'Cannot determine the entity type for "{entity_type}". Did you perhaps make a typo, or could it be that the entity type comes from another package that is not yet installed?', entity_type=str(value), ) ) from None return _assert_entity_type