Advanced Flask: Recipes For An All-weather Craft

Abstract: Flask is favoured for prototyping. It is easy to set up and run. However, choosing Flask as your main 'cheval de bataille', be it as a company or individual, requires solid grounding. Flask lets you choose your own ingredients, which lights up the joy of coding but bites if not being careful. This talk covers the standard techniques not to be missed as well as new audacious ones used to help manage BIG codebases.

Transcript

1. Advanced Flask: Recipes For An All-weather Craft
   

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2. PyCon Sweden
   

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4. Python Mauritius UserGroup (pymug)
   More info: mscc.mu/python-mauritius-usergroup-pymug/
   pymug.com
   Why Where
   codes github.com/pymug
   share events twitter.com/pymugdotcom
   ping professionals linkedin.com/company/pymug
   all info pymug.com
   tell friends by like facebook.com/pymug
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5. Abdur-Rahmaan Janhangeer
   
   (Just a Python programmer)
   twitter: @osdotsystem
   
   github: github.com/abdur-rahmaanj
   compileralchemy.com
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6. FlaskCon organising member + Flask Community Workgroup member
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7. Advanced Flask: Recipes For An All-weather Craft
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8. The Flask Story
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9. Begin new project
   
   
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10. Code features
    
    
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11. Deploy
    
    
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12. Refine Deploy
    
    
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13. TEST AND PROD ENV DIFFERENT
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14. USE CONFIGURATION PROFILES
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15. ADD APP FACTORY
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16. APP BREAKING
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17. WRITE TESTS
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18. CODE DISORGANISED
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19. ORGANISE CODEBASE
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20. TESTS ARE BORING
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21. WRITE FIXTURES, WRITE SCHEMAS
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22. I HAVE TO START A NEW PROJECT
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23. HAVE A TEMPLATE
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24. NOW I HAVE TO USE APIS
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25. INTEGRATE API-FRAMEWORK
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26. pulls some more hair
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27. I WANT TO INTEGRATE CELERY
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28. INTEGRATE CELERY
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29. dev left ...
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30. THE NEW INTERN DOES NOT UNDERSTAND ANYTHING
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31. WRITE DOCS!!!
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32. You need something that flies in all weather
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33. The Application Factory
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34. def create_app(app_name):
    
    app = Flask(app_name)
    
    
    
    return app
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35. Configuration Profiles
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36. class Config:
    
    TESTING = False
    
    class ProductionConfig(Config):
    
    FAV_FLOWER = 'rose'
    
    class DevelopmentConfig(Config):
    
    FAV_FLOWER = 'sunflower'
    
    class TestingConfig(Config):
    
    FAV_FLOWER = 'moonlight petal'
    
    TESTING = True
    
    36
    

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37. from config import ProductionConfig
    
    from config import DevelopmentConfig
    
    from config import TestingConfig
    
    profiles = {
    
    'development': DevelopmentConfig(),
    
    'production': ProductionConfig(),
    
    'testing': TestingConfig()
    
    }
    
    def create_app(profile):
    
    app = Flask(__name__)
    
    app.config.from_object(profiles[profile])
    
    return app
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38. Tests
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39. Use Pytest
    Use class-based testing
    Define fixtures for common actions e.g. logout/login
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40. Docs
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41. Use Sphinx from the start
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42. Separate Initialisations From The Factory
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43. Use a file for initialisations
    Reduces import errors to a max
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44. app.py
    
    init.py
    
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45. init.py
    db = SQLAlchemy()
    
    ma = Marshmallow()
    
    login_manager = LoginManager()
    
    migrate = Migrate()
    
    mail = Mail()
    
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46. from init import mail
    
    def create_app(...):
    
    app = ...
    
    mail.init_app(app)
    
    in other files: from init import db
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47. Use modules for everything!!!
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48. app.py
    
    module1/
    
    module2/
    
    module3/
    
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49. app.py
    
    modules/
    
    module1/
    
    module2/
    
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50. module1/
    
    templates/
    
    static/
    
    test/
    
    models.py
    
    forms.py
    
    view.py
    
    etc
    
    etc
    
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51. Use flask to simplify your life
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52. @app.cli.command("jump", short_help="skip something")
    
    def jump():
    
    # do something
    
    return 0
    
    # cli
    
    flask jump
    
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53. Automate blueprint registration
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54. 1. name each blueprint: foldername_blueprint
    2. In app.py
    # pseudocode
    
    for folder in modules:
    
    blueprint = import(f'modules.{folder}.view.{folder}_blueprint')
    
    app.register(blueprint)
    
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55. Automate module creation
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56. # pseudocode
    
    def createmodule(name):
    
    mkdir(folder)
    
    touch(folder/models.py)
    
    touch(folder/)
    
    ...
    
    # cli
    
    flask createmodule apple
    
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57. Form help yourself
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58. Use flask-wtf
    Use wtforms-alchemy
    class ConfForm(ModelForm):
    
    class Meta:
    
    model = Conf
    
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59. Contain static in module, implement collecstatic
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60. app.py
    
    static/ # served from here in production
    
    modules/
    
    m1/
    
    static/
    
    file.png
    m2/
    
    static/
    
    file.png
    collectstatic just collects all assets in all modules and add it under
    app.py
    
    static/
    
    modules/
    
    m1/
    
    file.png
    
    m2/
    
    file.png
    
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61. define function serve_asset(module, resource_path)
    
    e.g. serve_asset('m1', 'file.png')
    
    if mode is dev serve from /modules/m1/static/file.png
    
    i.e /modules/module_name/m1/static/path/to/file.png
    
    if mode is prod serve from /static/modules/m1/file.png (assumes collecstatic run before)
    
    i.e /static/modules/module_name/path/to/file.png
    
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62. What for celery?
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63. app.py
    
    init.py
    
    celery_app.py
    
    modules/
    
    m1/
    
    task.py
    
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64. init.py
    celery = Celery(
    
    __name__,
    
    broker=BaseConfig.CELERY_BROKER_URL,
    
    backend=BaseConfig.CELERY_RESULT_BACKEND,
    
    )
    
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65. app.py
    from init import celery
    
    def init_celery(app=None):
    
    app = create_app(os.getenv("FLASK_ENV", ""))
    
    app = app or create_app()
    
    celery.conf.update(app.config)
    
    class ContextTask(celery.Task):
    
    """Make celery tasks work with Flask app context"""
    
    def __call__(self, *args, **kwargs):
    
    with app.app_context():
    
    return self.run(*args, **kwargs)
    
    celery.Task = ContextTask
    
    return celery
    
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66. celery_app.py
    from app import init_celery
    
    celery = init_celery()
    
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67. modules/m1/task.py
    from init import celery
    
    @celery.task(name="do something", bind=True)
    
    def task_do_something(self):
    
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68. What for flask-restx?
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69. modules/
    
    app.py
    
    init.py
    
    api_util.py
    
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70. init.py
    api = Api(
    
    version="1.0",
    
    title="MVP Data",
    
    description="Backend Part",
    
    authorizations=authorizations,
    
    )
    
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71. api_util.py #
    from modules.some.api import some_ns
    
    from modules.some2.api import some2_ns
    
    # ns: namespace
    
    from init import api_v1
    
    api_v = api_v1 # /api/v1
    
    def add_api(api):
    
    api.add_namespace(some_ns, path=api_v + "/someapi")
    
    api.add_namespace(some2_ns, path=api_v + "/someapi2")
    
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72. app.py
    from init import api
    
    from api_util import add_api
    
    def create_app(...):
    
    app = ...
    
    api.init_app(app)
    
    add_api(api)
    
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73. Migrations to the next level
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74. # make flask-migrate auto detect models
    
    for folder in modules:
    
    import(f'modules.{folder}.models.py')
    
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75. Modular migration ideas:
    make flask_migrate or alembic load only specific classes
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76. Reuse base
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77. Use cookiecutter
    cookiecutter
    
    Keep modules and init.py empty
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78. The ongoing conclusion:
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79. https://github.com/shopyo/shopyo
    Star it to show support!
    79
    

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80. Helped you? appreciate a mail at: arj.python@gmail.com
    Really means a lot to me!!!!!
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