12 tips on Django Best Practices

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Some suggestions on Django development, deployment and external tools.

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12 tips on Django Best Practices

  1. 1. 12 tips on Django Best Practices David Arcos catchoom.com | @catchoom
  2. 2. 12 tips on Django Best Practices Some (personal) suggestions on: - Development - Deployment - External tools David Arcos | @DZPM Catchoom | http://catchoom.com
  3. 3. 12 tips on Django Best Practices Hi! I'm David Arcos - Python/Django developer - discovered Django in 2007 (v0.96) - professionally since 2008 - Web backend, distributed systems, databases, scalability, security - Team leader at Catchoom David Arcos | @DZPM Catchoom | http://catchoom.com
  4. 4. 12 tips on Django Best Practices - Image Recognition SaaS - Top recognition results, shortest response times - Easy to integrate into your apps/services David Arcos | @DZPM Catchoom | http://catchoom.com
  5. 5. 12 tips on Django Best Practices Why Python? PEP 20, The Zen of Python: - “Beautiful is better than ugly” - “Simple is better than complex” - “Complex is better than complicated” - “Readability counts” - “Special cases aren't special enough to break the rules” - “If the implementation is hard to explain, it's a bad idea” - (…) http://www.python.org/dev/peps/pep-0020/ David Arcos | @DZPM Catchoom | http://catchoom.com
  6. 6. 12 tips on Django Best Practices Why Django? - "The Web framework for perfectionists with deadlines" - Django design philosophy: - loose coupling, less code, DRY, consistency, etc... - https://docs.djangoproject.com/en/dev/misc/design-philosophies/ - technically: tons of django apps, very good doc David Arcos | @DZPM Catchoom | http://catchoom.com
  7. 7. 12 tips on Django Best Practices Virtualenv: - “one project, one virtualenv” - projects with different dependencies, package versions - easier to deploy. Forget dependency hell! - virtualenvwrapper is a convenient tool David Arcos | @DZPM Catchoom | http://catchoom.com
  8. 8. 12 tips on Django Best Practices Dependencies: - use pip: pip install catchoom - save the dependencies in a requirements.txt file: pip freeze > requirements.txt pip install -r requirements.txt David Arcos | @DZPM Catchoom | http://catchoom.com
  9. 9. 12 tips on Django Best Practices Layout: projects and apps - project = the full website. app = python library repository/ |-- doc `-- project |-- apps | |-- app1 | |-- app2 | `-- app3 `-- settings David Arcos | @DZPM Catchoom | http://catchoom.com
  10. 10. 12 tips on Django Best Practices - use short, obvious, single-word names for your apps - many small apps is better than a few giant apps: - explain an app in a sentence. If you can't, split the app - rather than expand an app, write a new app - don't reinvent the wheel! - django.contrib - 3rd-party apps David Arcos | @DZPM Catchoom | http://catchoom.com
  11. 11. 12 tips on Django Best Practices Settings: - multiple settings files: - per environment: dev, testing, staging, production - per developer (local settings, use the hostname) - all settings files must inherit from base, so you can do: INSTALLED_APPS += ('debug_toolbar', ) - version control all the settings! David Arcos | @DZPM Catchoom | http://catchoom.com
  12. 12. 12 tips on Django Best Practices Django is a MTV framework - Model (app/models.py) - Template (app/templates/*.html) - View (app/views.py) David Arcos | @DZPM Catchoom | http://catchoom.com
  13. 13. 12 tips on Django Best Practices Fat models, thin views... - logic should go to the models (and forms, signals...) - keep the views at a minimum Good example: django.contrib.auth.models.User David Arcos | @DZPM Catchoom | http://catchoom.com
  14. 14. 12 tips on Django Best Practices - why? Because of maintainability! - a model is much easier to test - reusable logic: form validation, signals, etc - the code becomes clearer, more self-documenting David Arcos | @DZPM Catchoom | http://catchoom.com
  15. 15. 12 tips on Django Best Practices ...and stupid templates! - your template layer should be as thin as possible - (by design) django templates are limited, constrained - doesn't fit your use case? Use jinja2 in those views - Hey, but I get ugly generated HTML! - doesn't matter, you want maintainable templates David Arcos | @DZPM Catchoom | http://catchoom.com
  16. 16. 12 tips on Django Best Practices Deployment: - web server: - Nginx + gunicorn - Supervisord to keep it alive. - static server: - Nginx. Or any CDN. David Arcos | @DZPM Catchoom | http://catchoom.com
  17. 17. 12 tips on Django Best Practices Fabric: "a library and command-line tool for streamlining the use of SSH for application deployment or systems administration tasks" - to automate deployments, migrations, execute management commands, monitoring... - no more repetitive maintainance tasks done manually! David Arcos | @DZPM Catchoom | http://catchoom.com
  18. 18. 12 tips on Django Best Practices South: "intelligent schema and data migrations for Django projects" - creates migration files automatically. - You can still do changes - can do backward migrations - will avoid disasters. Use it! David Arcos | @DZPM Catchoom | http://catchoom.com
  19. 19. 12 tips on Django Best Practices Celery: "asynchronous task queue/job queue based on distributed message passing" - execute tasks asynchronously, in a pool workers - cpu-intensive or I/O-intensive tasks: - emails, pdfs, thumbnails, crawling, requests... - Celery needs a Message Queue - Instead of RabbitMQ, try Redis. David Arcos | @DZPM Catchoom | http://catchoom.com
  20. 20. 12 tips on Django Best Practices Redis: "An advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets." - store ephemeral data (active sessions) - general cache (memcached compatible) - real-time calculations: stats, monitoring, throttling... - messages: channels (pub-sub), lists (push/blpop) - indexes/filters (“sort by hits”) David Arcos | @DZPM Catchoom | http://catchoom.com
  21. 21. 12 tips on Django Best Practices Sentry: "realtime event logging and aggregation platform" - monitor errors, get all the info to do a post-mortem - uses the Python logger, easy to configure - deploy a Sentry instance - or use getsentry.com David Arcos | @DZPM Catchoom | http://catchoom.com
  22. 22. 12 tips on Django Best Practices Debugging: - ipython (already in ./manage.py shell) - ipdb import ipdb ipdb.set_trace() - django-debug-toolbar - very powerful - use it to optimize db performance, view by view David Arcos | @DZPM Catchoom | http://catchoom.com
  23. 23. 12 tips on Django Best Practices Summary: - follow the Django philosophy (when possible) - stand on the shoulder of giants: use existing apps David Arcos | @DZPM Catchoom | http://catchoom.com
  24. 24. 12 tips on Django Best Practices Thanks for attending! - http://slideshare.net/DZPM - Questions? David Arcos | @DZPM Catchoom | http://catchoom.com
  25. 25. Questions? catchoom.com | @catchoom
  26. 26. 12 tips on Django Best Practices Thanks for attending! - http://slideshare.net/DZPM David Arcos | @DZPM Catchoom | http://catchoom.com

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