Drumbeat/MoJo/hackfest/berlin/sessions/django

Nicely formatted version: https://docs.google.com/document/d/1ShOTgjL1z299CLRmwFQ0MA7Ioa0ypmYDKE3ZJ31ME5A/edit?hl=en_US

This is a straight copy/paste:

Tango with Django (with Stijn) → https://docs.djangoproject.com

Flask: Microframework, good for no models and quick web stuffz. / http://flask.pocoo.org/ Stijn used for APIs, you may not need models.

PIP: Python Package Index → use virtualenv to manage various Django installations and versions. / http://pypi.python.org/pypi/pip Equivalent of Ruby’s RVM. Create virtual environment mkvirtualenv <name of project> --no-site-packages Activate the virtual environment source env/bin/activate Set up alias! Edit .bash_profile alias workon='source env/bin/activate' Now to activate your project environment, type: workon <name of project> Install Django & other infrastructure pip install django

Django extensions: very useful! Stijn will come back to this later.

requirements.txt To get a list of all installed, type pip freeze. pip freeze > requirements.txt → Pipe your contents into requirements.txt pip install -r requirements.txt → Installs all app requirements / dependencies.

For larger projects: common.txt development.txt → Django extensions, debugging production.txt → gunicorn: Server that is only used in production.

Deployment: can be as hard or as easy as you want. BASICS: Do it in the very same way you install something locally. Use different servers: Frontend → serve lots of requests at the same time and protect backend app. If frontend getting hammered, only send a couple requests to backedn. Ideal frontend server is nginx. Backend → use gunicorn port of Unicorn in Ruby world (!!) instead of python manage.py runserver. Install with pip. Uwgsi / Nginx module that replaces gunicorn. What about Git? If you have shell access on server, just SSH login to server, pull your repository. Create virtualenv there. Use this env to install requirements. Run server with gunicorn. Ways to make this easier: Fabric, like Capistrano. → Deployment tool, abstraction of this parent bullet. pip install fabric Fabric just consists of file with functions in it: RUN, which will run something on remote server specified. And LOCAL. Docs: http://docs.fabfile.org/en/1.2.2/index.html http://www.slideshare.net/andymccurdy/python-deployment-with-fabric [Slide 17] fabfile.py in project directory. fab list → list of available methods, which are the ones you’ve written.

Fixtures! Often when you are writing an app, you will need test data. Most people use Django admin and enter information in there -- which serves as test data. But problem is when you delete your db or someone else installs your app, or if you update your models and re-generate your database. South: Migration tool / http://south.aeracode.org/ fixture_gen.py → https://github.com/kzhu91/roundtable/blob/master/issues/fixture_gen.py Tool called Fixture generator.

Two ways to create fixtures: Standard but sucky

python manage.py dumpdata → dumps JSON. Then pump this into a file: initial.json. python manage.py loaddata initial.json

Annoyances: you don’t have control over what’s in your fixture or flexibility to change. Hence, fixture generator! Better way: use fixture generator → https://github.com/alex/django-fixture-generator

pip install fixturegenerator python manage.py generatefixture

Uses a decorator -- function that changes function into another function. If you’ve installed fixture-generator and added to INSTALLED_APPS in settings.py, issues.test_users. It will generate same JSON, but now, instead of having to edit the JSON, you can just very easily edit the fixture_gen.py.

Then you can just type fab reset. Now you have a fresh db with the initial data.

South: Database migrations Tad different if you’re using from existing app or from a fresh start.

New project, new app. Then install South (with pip). pip install south

In settings.py, we add South to INSTALLED_APPS.

python manage.py schemamigration --initial → pumps to file (?) --auto → shows your migrations?

Other cool stuff

Hate writing regular expressions when specifying Django urls? Try the surlex module. Deploying stuff? Learn about NGINX, gunicorn, upstart and fabric. Want some help debugging? Install django-extensions, which gives you two new management commands: python manage.py runserver_plus and python manage.py shell_plus. runserver_plus is just like runserver, but it will give you an interactive debugging console right in the browser whenever you make an error, so you can investigate what’s going wrong. shell_plus is like the regular shell command, but it preloads all your models, so you don’t have to import anything before you can start playing around with your models and your data.

An overview of some commands

1. create a virtual environment

mkdir myproj; cd myproj virtualenv env --no-site-packages

1. activate it

source env/bin/activate

1. (a shortcut, because you'll use this a lot -- add to your ~/.bashrc)

alias workon="source env/bin/activate"

1. installing software with pip

pip install django; pip install south; pip install django-extensions;

1. list all the software in your virtual environment

pip freeze

1. save that software into a requirements file

pip freeze > requirements.txt

1. install software from a requirements file

pip install -r requirements.txt

1. generate fixtures from a populated database

python manage.py dumpdata

1. generate fixtures with django-fixture-generator

python manage.py generate_fixture issues.test_users

1. working with south

python manage.py schemamigration myapp --initial python manage.py schemamigration myapp --auto

1. a list of all the commands in your Fabric fabfile

fab --list