112 lines
4.3 KiB
Python
112 lines
4.3 KiB
Python
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"""Cattrs validation."""
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from typing import Callable, List, Union
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from .errors import (
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ClassValidationError,
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ForbiddenExtraKeysError,
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IterableValidationError,
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)
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__all__ = ["format_exception", "transform_error"]
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def format_exception(exc: BaseException, type: Union[type, None]) -> str:
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"""The default exception formatter, handling the most common exceptions.
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The following exceptions are handled specially:
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* `KeyErrors` (`required field missing`)
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* `ValueErrors` (`invalid value for type, expected <type>` or just `invalid value`)
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* `TypeErrors` (`invalid value for type, expected <type>` and a couple special
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cases for iterables)
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* `cattrs.ForbiddenExtraKeysError`
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* some `AttributeErrors` (special cased for structing mappings)
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"""
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if isinstance(exc, KeyError):
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res = "required field missing"
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elif isinstance(exc, ValueError):
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if type is not None:
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tn = type.__name__ if hasattr(type, "__name__") else repr(type)
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res = f"invalid value for type, expected {tn}"
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else:
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res = "invalid value"
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elif isinstance(exc, TypeError):
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if type is None:
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if exc.args[0].endswith("object is not iterable"):
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res = "invalid value for type, expected an iterable"
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else:
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res = f"invalid type ({exc})"
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else:
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tn = type.__name__ if hasattr(type, "__name__") else repr(type)
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res = f"invalid value for type, expected {tn}"
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elif isinstance(exc, ForbiddenExtraKeysError):
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res = f"extra fields found ({', '.join(exc.extra_fields)})"
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elif isinstance(exc, AttributeError) and exc.args[0].endswith(
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"object has no attribute 'items'"
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):
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# This was supposed to be a mapping (and have .items()) but it something else.
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res = "expected a mapping"
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elif isinstance(exc, AttributeError) and exc.args[0].endswith(
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"object has no attribute 'copy'"
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):
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# This was supposed to be a mapping (and have .copy()) but it something else.
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# Used for TypedDicts.
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res = "expected a mapping"
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else:
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res = f"unknown error ({exc})"
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return res
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def transform_error(
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exc: Union[ClassValidationError, IterableValidationError, BaseException],
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path: str = "$",
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format_exception: Callable[
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[BaseException, Union[type, None]], str
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] = format_exception,
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) -> List[str]:
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"""Transform an exception into a list of error messages.
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To get detailed error messages, the exception should be produced by a converter
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with `detailed_validation` set.
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By default, the error messages are in the form of `{description} @ {path}`.
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While traversing the exception and subexceptions, the path is formed:
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* by appending `.{field_name}` for fields in classes
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* by appending `[{int}]` for indices in iterables, like lists
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* by appending `[{str}]` for keys in mappings, like dictionaries
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:param exc: The exception to transform into error messages.
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:param path: The root path to use.
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:param format_exception: A callable to use to transform `Exceptions` into
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string descriptions of errors.
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.. versionadded:: 23.1.0
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"""
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errors = []
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if isinstance(exc, IterableValidationError):
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with_notes, without = exc.group_exceptions()
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for exc, note in with_notes:
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p = f"{path}[{note.index!r}]"
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if isinstance(exc, (ClassValidationError, IterableValidationError)):
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errors.extend(transform_error(exc, p, format_exception))
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else:
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errors.append(f"{format_exception(exc, note.type)} @ {p}")
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for exc in without:
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errors.append(f"{format_exception(exc, None)} @ {path}")
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elif isinstance(exc, ClassValidationError):
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with_notes, without = exc.group_exceptions()
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for exc, note in with_notes:
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p = f"{path}.{note.name}"
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if isinstance(exc, (ClassValidationError, IterableValidationError)):
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errors.extend(transform_error(exc, p, format_exception))
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else:
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errors.append(f"{format_exception(exc, note.type)} @ {p}")
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for exc in without:
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errors.append(f"{format_exception(exc, None)} @ {path}")
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else:
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errors.append(f"{format_exception(exc, None)} @ {path}")
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return errors
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