Plugging into Flask

Transcript

1. Plugging into Flask Flask-NYC December 4, 2013
3. Andy Dirnberger @dirn github.com/dirn
4. >>> from flask.ext.sqlalchemy import SQLAlchemy
5. >>> from flask.ext.wtf import Form
6. >>> from flask.ext.mail import Mail
7. >>> from flask.ext import nyc
8. But that’s not how the code is laid out!
9. flask_sqlalchemy/__init__.py
10. flask_wtf/__init__.py
11. flask_mail.py
12. flask_nyc.py
13. What makes this work?
14. flask/ext/__init__.py
15. def setup(): from ..exthook import ExtensionImporter importer = ExtensionImporter(['flask_%s', 'flaskext.%s'], __name__) importer.install() ! ! setup() del setup
16. PEP-302 New Import Hooks http://www.python.org/dev/peps/pep-0302/
17. class MyCrazyImportHook: def find_module(self, fullname, path=None): “““Return a loader if the module is found.””” ! def load_module(self, fullname): “““Load the module or raise ImportError.”””
18. How to Build a Flask Extension http://flask.pocoo.org/extensions/
19. Pick a name
20. flask_myextension.py
21. Pick a license
22. • BSD (http://opensource.org/licenses/BSD-2- Clause, http://opensource.org/licenses/BSD-3- Clause) • MIT (http://opensource.org/licenses/MIT) • WTFPL (http://www.wtfpl.net/)
23. Write some tests
24. $ python setup.py test or! $ make test
25. Write some docs
26. $ sphinx-quickstart
27. https://github.com/mitsuhiko/flask-sphinx-themes
28. sys.path.append(os.path.abspath(‘_themes’)) html_theme_path = [‘_themes’] html_theme = ‘flask’ html_theme = ‘flask_small’
29. Add a setup.py
30. install_requires=[…]
31. zip_safe=False
32. Python 2.6 and 2.7
33. Anatomy of an Extension
34. class MyExtension: def __init__(self, app=None): self.app = app if app is not None: self.init_app(app)
35. from flask.ext.myextension import MyExtension ! app = Flask(__name__) MyExtension(app) # or my_extension = MyExtension() my_extension.init_app(app)
36. What’s in init_app?
37. def init_app(self, app): # Provide sane defaults app.config.setdefault(‘NYC_SETTING’) = True ! # Clean up after yourself app.teardown_appcontext(self.teardown)
38. init_app should not assign self.app
39. from flask import current_app
40. from flask import _app_ctx_stack as stack ! def teardown(self, exception): # Get the context ctx = stack.top ! # Take actions using the context
41. Flask-SQLAlchemy
42. from sqlalchemy import Column, Integer, String from sqlalchemy.ext.declarative import declarative_base ! Base = declarative_base() ! class User(Base): __tablename__ = ‘users’ ! id = Column(Integer, primary_key=True) name = Column(String)
43. from flask.ext.sqlalchemy import SQLAlchemy ! db = SQLAlchemy(app) ! class User(db.Model): __tablename__ = ‘users’ ! id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String)
44. Flask-WTF
45. from flask.ext.wtf import Form
46. class Form(SecureForm): “““ Flask-specific subclass of WTForms **SecureForm** class. ! ”””
47. Flask-Mail
48. from flask.ext.mail import Mail, Message ! mail = Mail(app) ! msg = Message( ‘Hello’, sender=‘andy@flask-nyc.org’, recipients=[‘andy@nycpython.com’], ) ! msg.body, msg.html = ‘Hello’, ‘<b>Hello</b>’ ! mail.send(msg)
49. Flask-NYC
51. Thank you!