示例

Author custom validators, converters, default factories, and custom serializers in attrs without falling into decorator illusions, signature mismatches, or serialization key drift

sha256:04534868bcf83a1c9437d56575f5b38eea5b61ac3a126103d53fa34f2fbd7310

案例

目标

Author custom validators, converters, default factories, and custom serializers in attrs without falling into decorator illusions, signature mismatches, or serialization key drift HOW

包

attrs 26.1.0

环境

python 3.12

创建时间

2026-08-17T03:18:45Z

契约

• assert custom @field.validator methods require (self, attribute, value) and fail with TypeError when defined with (self, value)
• assert validator return values are discarded and do not mutate the attribute value
• assert @username.validator on top of field(validator=[...]) chains all checks in sequence via _AndValidator
• assert validators.matches_re uses anchored re.match by default and rejects non-prefix matches
• assert validators.in_(Enum) follows Python 3.12 Enum membership: raw member values are accepted without conversion while absent values raise ValueError
• assert validators.not_ raises ValueError when the inner validator does not raise
• assert validators.deep_iterable and deep_mapping validate container types and all child items or key-value pairs
• assert validator=[optional(instance_of(int)), gt(0)] fails on None with TypeError because gt(0) still runs on None, while optional(and_(...)) protects the composite
• assert @field.converter does not exist on _CountingAttr and raises TypeError at class definition because field().converter is None
• assert converter=int with default=None crashes on __init__ with TypeError because converters execute on default values, requiring converters.optional(int)
• assert converters.pipe with default_if_none and to_bool chains fallback replacement and boolean conversion
• assert attrs.Converter(takes_self=True, takes_field=True) allows converters to receive (value, self, field) while raw 2-arg callables fail with TypeError
• assert on_setattr custom setters execute only on attribute assignment and never during __init__
• assert attrs permits default=[] without error at class definition, silently creating shared mutable state across instances
• assert Factory(takes_self=True) and @field.default compute dynamic defaults from self during initialization
• assert passing both default= and factory= to attrs.field raises ValueError
• assert attrs.asdict keys by attribute.name and not attribute.alias, causing Class(**attrs.asdict(obj)) to fail with TypeError on aliased fields
• assert attrs.asdict filter takes (attribute, value) -> bool and filters.exclude removes matching attributes
• assert attrs.asdict value_serializer requires (inst, field, value) and fails with TypeError on 2-arg callables
• assert attrs.evolve keys by alias and re-runs validators on new instances
• assert attrs.cmp_using customizes equality and ordering when order=True is set on class and field has both eq and order defined
• assert mandatory fields defined in a subclass after parent default fields raise ValueError at definition unless kw_only=True is specified

文件

• NOTES.md
• csx.json
• requirements.txt
• src/__init__.py
• src/models.py
• test/contract.py

下载已验证的构件 (tar.gz) — 契约实际运行的那些字节

原始种子者

csx-seed

验证回执

• python 3.12 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · python@1 · 2026-08-17 · ed25519:d91480838ac982c9