Django: Community and Conventions Primer

Given at Kansas City Developers Conference 2014

Transcript

1. DJANGO:
   COMMUNITY AND CONVENTIONS PRIMER Garrett Pennington @gpennington
2. GOALS 1. Basic Tutorial of Django 2. Have an understanding of the common tools used in the Django world 3. Introduction to Django community
7. DJANGO PEOPLE Adrian Holovaty @adrianholovaty github.com/adrianholovaty Projects: Django
 Everyblock
 Soundslice
8. DJANGO PEOPLE Jacob Kaplan-Moss @jacobian github.com/jacobian Projects: Django
9. ABOUT DJANGO • Python Web Framework • Created at the World company in Lawrence, KS by Adrian Holovaty, Simon Wilson, others • Open Source’d in 2005 under BSD License
 https://github.com/django/django

10. http://xkcd.com/353/
11. ABOUT DJANGO • Major sites include: • Pintrest • Instragram • Mozilla (Add-ons) • Disqus • Rdio
12. ABOUT DJANGO • Strengths • Developer Friendly • Included suite of apps • DRY friendly features • Build a whole lot for very little • Weaknesses • Monolithic (batteries included) • Swapping out pieces reduces their value as a whole. 

13. CODE OF CONDUCT • Code of Conduct
 https://www.djangoproject.com/conduct/ • Django Software Foundation
 https://www.djangoproject.com/foundation/

14. PYTHON 3 • Django is Python 3 Compatible • Still, not a strong adoption
15. DJANGO PYTHON PEOPLE Guido van Rossum @gvanrossum github.com/guido Projects: Python
16. WHERE TO GET HELP • IRC
 irc://irc.freenode.net/django • #django
 

17. GETTING STARTED
18. INSTALLING DJANGO pip install django
19. PIP • Awesome installation and package manager utility. • pip (Pip Installs Python)
 pip.readthedocs.org • Installs from PyPI (Python Package Index)
 https://pypi.python.org/pypi
20. INSTALLING PIP easy_install pip or Download get-pip.py
 https://bootstrap.pypa.io/get-pip.py
21. INSTALLING PIP
22. INSTALLING DJANGO pip install django Pip installed. Now? ! ! ! ! Not yet.
23. VIRTUALENV • virtualenv allows you to isolate python projects • Do this, even if you have one project • http://virtualenv.readthedocs.org/ • Authors: Ian Bicking, Jannis Leidel, Carl Meyer and Brian Rosner pip install virtualenv
24. DJANGO PEOPLE Jannis Leidel @jezdez github.com/jezdez Projects: virtualenv
 Django
 lots
25. VIRTUALENVWRAPPER • Handy extensions for virtualenv • Map projects to virtual environments • http://virtualenvwrapper.readthedocs.org • Authors: Doug Hellmann
 
 • Quick wrapper demo pip install virtualenvwrapper
26. DJANGO PEOPLE Doug Hellmann @doughellmann github.com/dhellmann Projects: virtualenvwrapper
 Python Standard Library by Example (http://www.amazon.com/ Python-Standard-Library-Example- Developers/dp/0321767349)

27. DID YOU READ IT? Notice anything about where Python docs live? https://readthedocs.org/ Hosted Sphinx generated documentation. Product of Django Dash. ! ! ahem...http://pymarvel.readthedocs.org
28. DJANGO PEOPLE Eric Holscher @ericholscher github.com/ericholscher Projects: readthedocs
 writethedocs

29. Pip installed. Virtualenv Activated. Now? Okay, now. ! ! ! INSTALLING DJANGO ! ! pip install django
 pip install django==1.6.5
 pip install django>=1.6,<1.7.0
 pip uninstall django
30. ! ! pip install -r requirements.txt Django is merely a dependency for your WSGI project. You’ll likely have more. Pip can take a requirements file. Add it to source control. You’re dependencies are now versioned and tracked. ! ! ! INSTALLING DJANGO
    AND FRIENDS
32. DJANGO-ADMIN.PY • Installing Django puts django-admin.py into your virtualenv bin directory. ! • Adds boilerplate, including WSGI and settings module. ! ! • Create or borrow a project template if you don’t like default. (I don’t) django-admin.py startproject myproject ! django-admin.py startproject -- template=<path to template> myproject
33. PROJECT ORGANIZATION /myproject
 /apps
 /foo_app
 /bar_app
 /settings
 /common.py
 /develop.py
 /hosted.py
 /alpha.py
 /production.py
 /conf
 requirements.txt
 myproject.wsgi
 fabfile.py
 urls.py
34. PROJECT VS APPLICATION Project:
 Django instance
 Settings Module Application:
 Python package (possibly reusable)
 Added to Django settings INSTALLED_APPS ! Let’s make a blog app!
35. TUTORIAL!
36. View Templates Web Server WSGI URLs Forms Models HTTP Response HTTP Request REQUEST LIFE CYCLE
37. View Templates Web Server WSGI URLs Forms Models HTTP Response HTTP Request REQUEST LIFE CYCLE
38. URLS • Uses regular expressions to find a match with requested URL • Matched expression passes request to view • URLs can pass parameters • URLs can be named
40. View Templates Web Server WSGI URLs Forms Models HTTP Response HTTP Request REQUEST LIFE CYCLE
41. VIEWS • A view accepts a request, returns an HTTP Response • Any response type, code • Convention is views.py • Views should be small • django.shortcuts.render • Can be method or class (CBV)
43. TEMPLATES • Templates are rendered using available Context • Context is a dictionary of values • Lists, Dictionaries, Strings, etc... • Querysets (List-like sets of Model queries) • Vast library of tags and filters-- or custom! • Too much logic in template is Code Smell
46. View Templates Web Server WSGI URLs Forms Models HTTP Response HTTP Request REQUEST LIFE CYCLE
47. MODELS • Python Class • Generally 1:1 Model class to DB Table • ORM (Object Relational Mapping) • Database agnostic • Methods for querying, creating data • Business Logic (fat models, skinny views)
50. `
51. ADMIN • Easy, free way to being development • Very customizable • Drawbacks: • Tied to Django’s ORM • Not suitable for end-users • Essentially a database tool, not a front facing UI • Quick Admin Demo
53. MODEL METHODS • Models have methods for interacting with an instance of data. • First, let’s add a detail view for an instance.
56. MODEL METHODS • Standard convention is to add __unicode__ method to provide handy way to represent an instance of a Model. • Also a good idea to provide a get_absolute_url method to determine where this resource lives.
60. MANGERS • Managers provide methods for interacting with sets of data. • You can write custom managers. ! ! FooModel.objects <-- Model Manager
 FooModel.objects.all() <-- Manager method
 FooModel.objects.featured() <-- Custom manager method !
65. ! ! pip install south
 <Make model schema changes...>
 MIGRATIONS • Django 1.7 provides out of the box schema migrations.
 (But 1.7 isn’t officially out yet...) • Use South for migrations! • South generates Migration files, which you can add to source control.
66. DJANGO PEOPLE Andrew Godwin @agodwin github.com/agodwin Projects: South
68. MIGRATIONS ! ! $ python manage.py schemamigration blog --auto + Added field sub_title on blog.Post Created 0002_auto__add_field_post_sub_title.py. You can now apply this migration with: ./manage.py migrate blog
70. MIGRATIONS ! ! $ python manage.py migrate blog Running migrations for blog: - Migrating forwards to 0002_auto__add_field_post_sub_title. > blog:0002_auto__add_field_post_sub_title
71. FABRIC • http://www.fabfile.org/ • Use Python to write remote (or local!) shell commands • Commonly used to deploy applications or perform maintenance tasks across any number of hosts. fab production deploy:2.0.4 fab run_local_server fab alpha kick_apache
72. THANK YOU! Questions?
73. Titanium  Sponsors Pla2num  Sponsors Gold  Sponsors