roughrider.workflow 0.2

Pure python workflow/transition system.

This package allows to define workflows that consist of a set of states, transitions between the states. Actions that activate the transitions can be guarded by constraints.

Example

from roughrider.predicate import ConstraintError, Validator, Or
from roughrider.workflow.components import Action, Transition, Transitions
from roughrider.workflow.workflow import (
    WorkflowItem, WorkflowState, Workflow)


class Document:
    state = None
    body = ""


class RoleValidator(Validator):

    def __init__(self, role):
        self.role = role

    def __call__(self, item, role=None, **namespace):
        if role != self.role:
            raise ConstraintError(
                message=f'Unauthorized. Missing the `{role}` role.')


class PublicationWorkflow(Workflow):

    class wrapper(WorkflowItem):

        @property
        def state(self):
            return self.workflow.get(self.item.state)

        @state.setter
        def state(self, state):
            self.item.state = state.name


    class states(WorkflowState):
        draft = 'Draft'
        published = 'Published'
        submitted = 'Submitted'


    transitions = Transitions((
        Transition(
            origin=states.draft,
            target=states.published,
            action=Action(
                'Publish',
                constraints=[RoleValidator('publisher')]
            )
        ),
        Transition(
            origin=states.published,
            target=states.draft,
            action=Action(
                'Retract',
                constraints=[
                    Or((RoleValidator('owner'),
                        RoleValidator('publisher')))
                ]
            )
        ),
        Transition(
            origin=states.draft,
            target=states.submitted,
            action=Action(
                'Submit',
                constraints=[RoleValidator('owner')],
            )
        ),
        Transition(
            origin=states.submitted,
            target=states.published,
            action=Action(
                'Publish',
                constraints=[RoleValidator('publisher')],
            )
        )
    ))


workflow = PublicationWorkflow('draft')  # initial state
item = Document()
workflow_item = workflow(item, role='owner')
workflow_item.transition_to(PublicationWorkflow.states.submitted)

CHANGES

0.2 (2021-10-21)

• Updating to use roughrider.predicate >= 0.3.1

0.1 (2021-10-09)

• Initial release.