validated-dc 0.2.4

Dataclass with data validation.

ValidatedDC

Dataclass with data validation. Checks the value of its fields by their annotations.

Capabilities

ValidatedDC is a regular Python dataclass, but with the ability to check the validity of the data by which this dataclass was initialized. Also, you can check the data at any time during the life of the instance.

1. Support for standard and custom Python classes.
2. Support for some aliases from the typing module, namely: Any, List, Literal, Optional, Union.
3. Replacing the dict with an instance of the dataclass from the field annotation (for example, when receiving data by api). If this behavior is not necessary, then the replacement can be disabled as follows:

@dataclass
class CustomValidatedDC(ValidatedDC):
    def _init_validation(self) -> None:
        super()._init_validation()
        self._replace = False

See detailed examples in examples.py.

Installation

pip install validated-dc

Simple example

from validated_dc import ValidatedDC
from dataclasses import dataclass

from typing import List, Union


@dataclass
class Foo(ValidatedDC):
    foo: int


@dataclass
class Bar(ValidatedDC):
    bar: Union[Foo, List[Foo]]


foo = {'foo': 1}
instance = Bar(bar=foo)
print(instance.get_errors())  # None
print(instance)               # Bar(bar=Foo(foo=1))

list_foo = [{'foo': 1}, {'foo': 2}]
instance = Bar(bar=list_foo)
print(instance.get_errors())  # None
print(instance)               # Bar(bar=[Foo(foo=1), Foo(foo=2)])

instance.bar.append({'foo': '3'})
print(instance.is_valid())    # False
print(instance.get_errors())
# {'bar': [InstanceValidationError(instance_class=<class '__main__.Foo'>,
# errors={'foo': [BasicValidationError(value='3', annotation=<class 'int'>,
# exception=None)]}, exception=None), ListValidationError(item_number=2,
# item_value={'foo': '3'}, annotation=<class '__main__.Foo'>)]}


print(instance)  # Bar(bar=[Foo(foo=1), Foo(foo=2), {'foo': '3'}])

instance.bar[2]['foo'] = 3
print(instance)  # Bar(bar=[Foo(foo=1), Foo(foo=2), {'foo': 3}])
print(instance.is_valid())    # True
print(instance.get_errors())  # None
print(instance)  # Bar(bar=[Foo(foo=1), Foo(foo=2), Foo(foo=3)]

instance.bar[2].foo = '3'
print(instance)  # Bar(bar=[Foo(foo=1), Foo(foo=2), Foo(foo='3')])
print(instance.is_valid())  # False
print(instance.get_errors())
# {'bar': [InstanceValidationError(instance_class=<class '__main__.Foo'>,
# errors={'foo': [BasicValidationError(value='3', annotation=<class 'int'>,
# exception=None)]}, exception=None), ListValidationError(item_number=2,
# item_value=Foo(foo='3'), annotation=<class '__main__.Foo'>)]}