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https://github.com/woile/pyfsm
:arrows_counterclockwise: Minimal State Machine
https://github.com/woile/pyfsm
finite-state-machine fsm python state-machine
Last synced: 4 months ago
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:arrows_counterclockwise: Minimal State Machine
- Host: GitHub
- URL: https://github.com/woile/pyfsm
- Owner: woile
- License: mit
- Created: 2016-04-18T21:56:53.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2021-05-11T11:57:28.000Z (almost 4 years ago)
- Last Synced: 2024-10-15T04:27:46.259Z (4 months ago)
- Topics: finite-state-machine, fsm, python, state-machine
- Language: Python
- Homepage: https://pyfsm.readthedocs.org/
- Size: 47.9 KB
- Stars: 21
- Watchers: 4
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.rst
- Changelog: CHANGELOG.rst
- Contributing: CONTRIBUTING.rst
- License: LICENSE
Awesome Lists containing this project
README
========
Overview
========
.. start-badges
.. list-table::
:stub-columns: 1
* - docs
- |docs|
* - tests
- | |travis|
| |codecov|
* - package
- |version| |wheel| |supported-versions| |supported-implementations|
.. |docs| image:: https://img.shields.io/readthedocs/pip.svg?style=flat-square
:alt: Read the Docs
:target: https://readthedocs.org/projects/pyfsm
.. |travis| image:: https://img.shields.io/travis/Woile/pyfsm.svg?style=flat-square
:alt: Travis-CI Build Status
:target: https://travis-ci.org/Woile/pyfsm
.. |codecov| image:: https://img.shields.io/codecov/c/github/Woile/pyfsm.svg?style=flat-square
:alt: Coverage Status
:target: https://codecov.io/github/Woile/pyfsm
.. |version| image:: https://img.shields.io/pypi/v/fsmpy.svg?style=flat-square
:alt: PyPI Package latest release
:target: https://pypi.python.org/pypi/fsmpy
.. |wheel| image:: https://img.shields.io/pypi/wheel/fsmpy.svg?style=flat-square
:alt: PyPI Wheel
:target: https://pypi.python.org/pypi/fsmpy
.. |supported-versions| image:: https://img.shields.io/pypi/pyversions/fsmpy.svg?style=flat-square
:alt: Supported versions
:target: https://pypi.python.org/pypi/fsmpy
.. |supported-implementations| image:: https://img.shields.io/pypi/implementation/fsmpy.svg?style=flat-square
:alt: Supported implementations
:target: https://pypi.python.org/pypi/fsmpy
.. end-badges
Minimal state machine
* Free software: BSD license
.. code-block:: python
import fsm
class MyTasks(fsm.FiniteStateMachineMixin):
"""An example to test the state machine.
Contains transitions to everywhere, nowhere and specific states.
"""
state_machine = {
'created': '__all__',
'pending': ('running',),
'running': ('success', 'failed'),
'success': None,
'failed': ('retry',),
'retry': ('pending', 'retry'),
}
def __init__(self, state):
"""Initialize setting a state."""
self.state = state
def on_before_pending(self):
print("I'm going to a pending state")
::
In [4]: m = MyTasks(state='created')
In [5]: m.change_state('pending')
I'm going to a pending state
Out[5]: 'pending'
::
In [6]: m.change_state('failed') # Let's try to transition to an invalid state
---------------------------------------------------------------------------
InvalidTransition Traceback (most recent call last)
in ()
----> 1 m.change_state('failed')
~/pyfsm/src/fsm/fsm.py in change_state(self, next_state, **kwargs)
90 msg = "The transition from {0} to {1} is not valid".format(previous_state,
91 next_state)
---> 92 raise InvalidTransition(msg)
93
94 name = 'pre_{0}'.format(next_state)
InvalidTransition: The transition from pending to failed is not valid
.. contents::
:depth: 2
Installation
============
::
pip install fsmpy
Usage
======
1. Define in a class the :code:`state_machine`
2. Initialize :code:`state`, either with a value, using :code:`__init__` or as a django field
3. Add hooks:
+------------------------+-------------------------------------------------------------------------------------------------------------+
| Method | Description |
+------------------------+-------------------------------------------------------------------------------------------------------------+
| on_before_change_state | Before transitioning to the state |
+------------------------+-------------------------------------------------------------------------------------------------------------+
| on_change_state | After transitioning to the state, if no failure, runs for every state |
+------------------------+-------------------------------------------------------------------------------------------------------------+
| pre_ | Runs before a particular state, where :code:`state_name` is the specified name in the :code:`state_machine` |
+------------------------+-------------------------------------------------------------------------------------------------------------+
| post_ | Runs after a particular state, where :code:`state_name` is the specified name in the :code:`state_machine` |
+------------------------+-------------------------------------------------------------------------------------------------------------+
This hooks will receive any extra argument given to :code:`change_state`
E.g:
Running :code:`m.change_state('pending', name='john')` will trigger :code:`pre_pending(name='john')`
Django integration
==================
.. code-block:: python
import fsm
from django.db import models
class MyModel(models.Model, fsm.FiniteStateMachineMixin):
"""An example to test the state machine.
Contains transitions to everywhere, nowhere and specific states.
"""
CHOICES = (
('created', 'CREATED'),
('pending', 'PENDING'),
('running', 'RUNNING'),
('success', 'SUCCESS'),
('failed', 'FAILED'),
('retry', 'RETRY'),
)
state_machine = {
'created': '__all__',
'pending': ('running',),
'running': ('success', 'failed'),
'success': None,
'failed': ('retry',),
'retry': ('pending', 'retry'),
}
state = models.CharField(max_length=30, choices=CHOICES, default='created')
def on_change_state(self, previous_state, next_state, **kwargs):
self.save()
Django Rest Framework
---------------------
If you are using :code:`serializers`, they usually perform the :code:`save`, so saving inside :code:`on_change_state` is not necessary.
One simple solution is to do this:
.. code-block:: python
class MySerializer(serializers.ModelSerializer):
def update(self, instance, validated_data):
new_state = validated_data.get('state', instance.state)
try:
instance.change_state(new_state)
except fsm.InvalidTransition:
raise serializers.ValidationError("Invalid transition")
instance = super().update(instance, validated_data)
return instance
Documentation
=============
https://pyfsm.readthedocs.org/
Development
===========
To run the tests run::
tox
Note, to combine the coverage data from all the tox environments run:
.. list-table::
:widths: 10 90
:stub-columns: 1
- - Windows
- ::
set PYTEST_ADDOPTS=--cov-append
tox
- - Other
- ::
PYTEST_ADDOPTS=--cov-append tox