Large-Scale Applications with Flask: Doing More With Less

In this session I show you how you can take Flask, a so-called "microframework", and write readable, usable, testable and intelligent code for all of your macro-scale applications. We'll go through basic API design, ORM integration (including some popular non-relational databases), modular design with blueprints, and testing. By the end of this talk, you'll understand why Flask is the little framework that lets you do a lot, and be armed with the tools & knowledge to write applications of all sizes.

Transcript

1. DOING MORE WITH LESS
   Large Scale Apps with
   FLASK
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2. Pocoo
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3. Friday, 2 March, 12
   

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4. JINJA
   FLASK
   PYGMENTS
   WERKZEUGSPHINX
   ...
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5. MICROFramework
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6. MICRO
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7. Database Abstraction
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8. Database Abstraction
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9. Form Validation
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10. Form Validation
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11. Django-ish Admin
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12. Django-ish Admin
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13. Jinja 2 Werkzeug
    &
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14. Templating WSGI
    &
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15. Tools
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16. Friday, 2 March, 12
    

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17. gunicorn
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18. gunicorn
    gevent
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19. gunicorn
    gevent
    nginx
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20. Friday, 2 March, 12
    

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21. unittest2/nose
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22. unittest2/nose
    lettuce
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23. Friday, 2 March, 12
    

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24. fabric
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25. fabric
    virtualenv
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26. fabric
    virtualenv
    jenkins
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27. RESTful/ish APIs
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28. Warning
    CODE BEYOND THIS POINT
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29. Friday, 2 March, 12
    

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30. from flask import Flask
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31. from flask import Flask
    app = Flask(__name__)
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32. from flask import Flask
    app = Flask(__name__)
    @app.route("/")
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33. from flask import Flask
    app = Flask(__name__)
    @app.route("/")
    def hello():
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34. from flask import Flask
    app = Flask(__name__)
    @app.route("/")
    def hello():
    return "Hello World!"
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35. from flask import Flask
    app = Flask(__name__)
    @app.route("/")
    def hello():
    return "Hello World!"
    if __name__ == "__main__":
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36. from flask import Flask
    app = Flask(__name__)
    @app.route("/")
    def hello():
    return "Hello World!"
    if __name__ == "__main__":
    app.run()
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37. $ pythonhello.py
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38. Werkzeug Router
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39. Friday, 2 March, 12
    

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40. @app.route(‘/’)
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41. @app.route(‘/dashboard’)
    @app.route(‘/’)
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42. @app.route(‘/dashboard’)
    @app.route(‘/’)
    @app.route(‘/pages/’)
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43. @app.route(‘/dashboard’)
    @app.route(‘/’)
    @app.route(‘/pages/’)
    @app.route(‘/user/’)
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44. @app.route(‘/dashboard’)
    @app.route(‘/’)
    @app.route(‘/pages/’)
    @app.route(‘/user/’)
    @app.route(‘/posts//’)
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45. @app.route(‘/dashboard’)
    @app.route(‘/’)
    @app.route(‘/pages/’)
    @app.route(‘/user/’)
    @app.route(‘/posts//’)
    @app.route(‘/’)
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46. Custom Converters
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47. from werkzeug.routing import BaseConverter
    class ListConverter(BaseConverter):
    def to_python(self, value):
    return value.split(',')
    def to_url(self, values):
    return
    ','.join(BaseConverter.to_url(value)
    for value in values)
    app = Flask(__name__)
    app.url_map.converters['list'] = ListConverter
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48. Testing
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49. Friday, 2 March, 12
    

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50. UNITTEST
    FACTORY_BOY
    LETTUCE
    NOSEMOCK
    ...
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51. Friday, 2 March, 12
    

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52. Thread/Context Locals
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53. with app.test_request_context('/posts?sort=asc&limit=10'):
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54. with app.test_client() as client:
    result = client.get('/posts?sort=asc&limit=10')
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55. Useful Extensions
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56. Friday, 2 March, 12
    

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57. Flask-Login
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58. Flask-Login
    Flask-Testing
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59. Flask-Login
    Flask-Testing
    Flask-WTForms
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60. Flask-Login
    Flask-Testing
    Flask-WTForms
    Flask-Bcrypt
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61. Flask-Login
    Flask-Testing
    Flask-WTForms
    Flask-Bcrypt
    Flask-Assets
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62. ORM Integration
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63. Friday, 2 March, 12
    

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64. SQLAlchemy
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65. SQLAlchemy
    MongoKit
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66. SQLAlchemy
    MongoKit
    Pycassa
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67. SQLAlchemy
    MongoKit
    Pycassa
    CouchDB
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68. from flask import Flask
    from flaskext.sqlalchemy import SQLAlchemy
    app = Flask(__name__)
    app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:////tmp/test.db'
    db = SQLAlchemy(app)
    class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True)
    email = db.Column(db.String(120), unique=True)
    def __init__(self, username, email):
    self.username = username
    self.email = email
    def __repr__(self):
    return '' % self.username
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69. from flask import Flask
    from mongokit import Connection, Document
    # configuration
    MONGODB_HOST = 'localhost'
    MONGODB_PORT = 27017
    # create the little application object
    app = Flask(__name__)
    app.config.from_object(__name__)
    # connect to the database
    connection = Connection(app.config['MONGODB_HOST'],
    app.config['MONGODB_PORT'])
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70. class Post(Document):
    structure = {
    'title':unicode,
    'body':unicode,
    'author':unicode,
    'date_creation':datetime.datetime,
    'rank':int,
    'tags': [unicode],
    }
    required_fields = ['title','author', 'date_creation']
    default_values = {'rank':0, 'date_creation': datetime.datetime.utcnow}
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71. Callbacks/hooks
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72. Friday, 2 March, 12
    

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73. @app.before_request
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74. @app.before_request
    @app.after_request
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75. @app.before_request
    @app.after_request
    @app.before_first_request
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76. @app.before_request
    @app.after_request
    @app.before_first_request
    @app.errorhandler
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77. @app.before_request
    @app.after_request
    @app.before_first_request
    @app.errorhandler
    ...
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78. Signals via Blinker
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79. Friday, 2 March, 12
    

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80. flask.template_rendered
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81. flask.request_started
    flask.template_rendered
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82. flask.request_started
    flask.request_finished
    flask.template_rendered
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83. flask.request_started
    flask.request_finished
    flask.template_rendered
    flask.got_request_exception
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84. flask.request_started
    flask.request_finished
    flask.template_rendered
    flask.got_request_exception
    flask.request_tearing_down
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85. In-process event
    dispatching
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86. Not the same as
    callbacks/hooks
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87. API Design
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88. Start thinking in terms of
    datastructures
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89. And breaking up your
    application in to services
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90. Instead of staying in the
    MVC Bubble.
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91. Blueprints
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92. from flask import Blueprint, render_template, abort
    from jinja2 import TemplateNotFound
    static_page = Blueprint('static_page', __name__,
    template_folder='templates')
    @static_page.route('/')
    def show(page):
    try:
    return render_template('pages/%s.html' % page)
    except TemplateNotFound:
    abort(404)
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93. from flask import Flask
    from myapp.static_page import static_page
    app = Flask(__name__)
    app.register_blueprint(static_page, url_prefix= ‘/pages’)
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94. Blueprints have their own
    templates, static files,
    and callbacks/hooks.
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95. Pluggable Views
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96. @app.route('/users/')
    def show_users(page):
    users = User.query.all()
    return render_template('users.html', users=users)
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97. from flask.views import View
    class ShowUsers(View):
    def dispatch_request(self):
    users = User.query.all()
    return render_template('users.html', objects=users)
    app.add_url_rule('/users/', ShowUsers.as_view('show_users'))
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98. from flask.views import View
    class ListView(View):
    def get_template_name(self):
    raise NotImplementedError()
    def render_template(self, context):
    return render_template(self.get_template_name(), **context)
    def dispatch_request(self):
    context = {'objects': self.get_objects()}
    return self.render_template(context)
    class UserView(ListView):
    def get_template_name(self):
    return 'users.html'
    def get_objects(self):
    return User.query.all()
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99. Method-Based
    Dispatching
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100. from flask.views import MethodView
     class User(MethodView):
     def get(self):
     users = User.query.all()
     ...
     def post(self):
     user = User.from_form_data(request.form)
     ...
     app.add_url_rule('/users/', view_func=User.as_view('users'))
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101. QUESTIONS?
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102. Fictive Kin
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103. @jperras
     Joël Perras
     http://nerderati.com
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