roughrider.predicate 0.3.1

Pure python predicate/guard/validation system.

This package helps defining and creating small and reusable components that can serve as guard or validation methods.

Example

Below is an example of a validation on a content item.

from dataclasses import dataclass
from roughrider.predicate.errors import ConstraintError
from roughrider.predicate.validators import Validator, Or


@dataclass
class Document:
    id: str
    body: str = ''
    content_type: str = 'text/plain'


def non_empty_document(item):
    """Implementation of a validator/predicate
    """
    if not item.body:
        raise ConstraintError('Body is empty.')


class ContentType(Validator):

    def __init__(self, content_type):
        self.ct = content_type

    def __call__(self, item):
        if item.content_type != self.ct:
            raise ConstraintError(
                f'Expected {self.ct}, got {item.content_type}.')


  validator = Or((
      ContentType('text/plain'),
      Or((ContentType('text/html'), non_empty_document))
  ))
  document = Document(id='test', content_type='application/json')
  validator(document)  # raises ConstraintsErrors

CHANGES

0.3.1 (2021-10-21)

• Changing packaging of extensions.

0.3 (2021-10-21)

• Code reorganization and Cython optimizations.

0.2 (2021-10-20)

• Correction of the resolve_validator errors list extension.

0.1 (2021-10-09)

• Initial release.