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
2. PyCon Sweden
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 4
5. Abdur-Rahmaan Janhangeer (Just a Python programmer) twitter: @osdotsystem github: github.com/abdur-rahmaanj compileralchemy.com 5
6. FlaskCon organising member + Flask Community Workgroup member 6
7. Advanced Flask: Recipes For An All-weather Craft 7
8. The Flask Story 8
9. Begin new project 9
10. Code features 10
11. Deploy 11
12. Refine Deploy 12
13. TEST AND PROD ENV DIFFERENT 13
14. USE CONFIGURATION PROFILES 14
15. ADD APP FACTORY 15
16. APP BREAKING 16
17. WRITE TESTS 17
18. CODE DISORGANISED 18
19. ORGANISE CODEBASE 19
20. TESTS ARE BORING 20
21. WRITE FIXTURES, WRITE SCHEMAS 21
22. I HAVE TO START A NEW PROJECT 22
23. HAVE A TEMPLATE 23
24. NOW I HAVE TO USE APIS 24
25. INTEGRATE API-FRAMEWORK 25
26. pulls some more hair 26
27. I WANT TO INTEGRATE CELERY 27
28. INTEGRATE CELERY 28
29. dev left ... 29
30. THE NEW INTERN DOES NOT UNDERSTAND ANYTHING 30
31. WRITE DOCS!!! 31
32. You need something that flies in all weather 32
33. The Application Factory 33
34. def create_app(app_name): app = Flask(app_name) return app 34
35. Configuration Profiles 35
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
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 37
38. Tests 38
39. Use Pytest Use class-based testing Define fixtures for common actions e.g. logout/login 39
40. Docs 40
41. Use Sphinx from the start 41
42. Separate Initialisations From The Factory 42
43. Use a file for initialisations Reduces import errors to a max 43
44. app.py init.py 44
45. init.py db = SQLAlchemy() ma = Marshmallow() login_manager = LoginManager() migrate = Migrate() mail = Mail() 45
46. from init import mail def create_app(...): app = ... mail.init_app(app) in other files: from init import db 46
47. Use modules for everything!!! 47
48. app.py module1/ module2/ module3/ 48
49. app.py modules/ module1/ module2/ 49
50. module1/ templates/ static/ test/ models.py forms.py view.py etc etc 50
51. Use flask to simplify your life 51
52. @app.cli.command("jump", short_help="skip something") def jump(): # do something return 0 # cli flask jump 52
53. Automate blueprint registration 53
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) 54
55. Automate module creation 55
56. # pseudocode def createmodule(name): mkdir(folder) touch(folder/models.py) touch(folder/) ... # cli flask createmodule apple 56
57. Form help yourself 57
58. Use flask-wtf Use wtforms-alchemy class ConfForm(ModelForm): class Meta: model = Conf 58
59. Contain static in module, implement collecstatic 59
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 60
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 61
62. What for celery? 62
63. app.py init.py celery_app.py modules/ m1/ task.py 63
64. init.py celery = Celery( __name__, broker=BaseConfig.CELERY_BROKER_URL, backend=BaseConfig.CELERY_RESULT_BACKEND, ) 64
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 65
66. celery_app.py from app import init_celery celery = init_celery() 66
67. modules/m1/task.py from init import celery @celery.task(name="do something", bind=True) def task_do_something(self): 67
68. What for flask-restx? 68
69. modules/ app.py init.py api_util.py 69
70. init.py api = Api( version="1.0", title="MVP Data", description="Backend Part", authorizations=authorizations, ) 70
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") 71
72. app.py from init import api from api_util import add_api def create_app(...): app = ... api.init_app(app) add_api(api) 72
73. Migrations to the next level 73
74. # make flask-migrate auto detect models for folder in modules: import(f'modules.{folder}.models.py') 74
75. Modular migration ideas: make flask_migrate or alembic load only specific classes 75
76. Reuse base 76
77. Use cookiecutter cookiecutter <url> Keep modules and init.py empty 77
78. The ongoing conclusion: 78
79. https://github.com/shopyo/shopyo Star it to show support! 79
80. Helped you? appreciate a mail at: arj.python@gmail.com Really means a lot to me!!!!! 80