Runtime validators for attrs
attrs runtime validation
attrs-strict is a Python package that contains runtime validation for
attrs data classes based on the types existing in the typing module.
The purpose of the library is to provide runtime validation for attributes specified in
attrs data classes. The types supported are all the builtin
types and most of the ones defined in the typing library. For Python 2, the typing module is
available through the backport found
Type enforcement is based on the
type attribute set on any field specified in an
attrs dataclass. If the type argument is not specified no validation takes place.
pip install attrs-strict
from typing import List import attr from attrs_strict import type_validator >>> @attr.s ... class SomeClass(object): ... list_of_numbers = attr.ib( ... validator=type_validator(), ... type=List[int] ... ) ... >>> sc = SomeClass([1,2,3,4]) >>> sc SomeClass(list_of_numbers=[1, 2, 3, 4]) >>> try: ... other = SomeClass([1,2,3,'four']) ... except ValueError as error: ... print(repr(error)) attrs_strict._error.AttributeTypeError: list_of_numbers must be typing.List[int] (got four that is a <class 'str'>) in [1, 2, 3, 'four']
Nested type exceptions are validated acordingly, and a backtrace to the initial container is maintained to ease with debugging. This means that if an exception occurs because a nested element doesn't have the correct type, the representation of the exception will contain the path to the specific element that caused the exception.
from typing import List, Tuple import attr from attrs_strict import type_validator >>> @attr.s ... class SomeClass(object): ... names = attr.ib( ... validator=type_validator(), type=List[Tuple[str, str]] ... ) >>> sc = SomeClass(names=[('Moo', 'Moo'), ('Zoo',123)]) attrs_strict._error.AttributeTypeError: names must be typing.List[typing.Tuple[str, str]] (got 123 that is a <class 'int'>) in ('Zoo', 123) in [('Moo', 'Moo'), ('Zoo', 123)]
What is currently supported ?
Currently there's support for simple types and types specified in the
Tuple and any combination of them. This means that you can specify nested types like
List[List[Dict[int, str]]] and the validation would check if attribute has the specific type.
Generics are not supported yet but there are plans to support this in the future.
For development, the project uses
tox in order to install dependencies, run tests and generate documentation. In order to be able to do this, you need tox
pip install tox and after that invoke
tox in the root of the project.
For the latest version, on github
pip install git+https://github.com/bloomberg/attrs-strict.
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