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PyBCDjango
= Web Development: An introduction to Django = '''Python Boot Camp 2010 - Django Break-Out - January 13'''
'''Presented By: Nico Preston'''
== References == This tutorial is modified from [http://www.informit.com/articles/article.aspx?p=1273658 Blog for the Impatient] by Forcier, Bissex, and Chung. These authors have made numerous outstanding contributions to the Python Community. This book is an excellent resource for learning Django. There is also an excellent primer on python in Chapter 1. The book can be accessed by UW students, faculty, and staff, through Safari Books Online via UW Library Electronic resources.
== Installing Django ==
This tutorial assumes you've followed the Python installation instructions for the earlier in this Python Bootcamp [http://hackerwithin.org/cgi-bin/hackerwithin.fcgi/wiki/PyBc/Session01#InstallingPython InstallingPython] .
It is easiest to install Django from source. Even better, by accessing the SVN (subversion) releases you'll get the most up-to-date version of Django for development applications. For production applications you may want to download and freeze a version (e.g. virtualenv) to ensure compatibilities.
Here is how to acquire Django from the command line (Linux, Mac, and Windows):
=== Linux ===
'''Note: you may need to sudo'''
Use your package manager {{{ apt-get django }}}
'' OR ''
Download and build from source {{{ cd desktop wget http://www.djangoproject.com/download/1.1.1/tarball/ tar xzvf Django-1.1.1.tar.gz cd Django-1.1.1 sudo python setup.py install
export PATH=/usr/local/lib/python2.6/dist-packages/django/bin/:$PATH }}}
=== Mac ===
'''Note: you may need to sudo'''
''' OS X command line (Enthought Python installation)''' {{{ cd /Library/Frameworks/Python.framework/Versions/6.0.0/lib/python2.6 sudo svn co http://code.djangoproject.com/svn/django/tags/releases/1.1.1/django sudo ln -s /Library/Frameworks/Python.framework/Versions/6.0.0/lib/python2.6/django/bin/django-admin.py /usr/bin/django-admin.py }}}
''' OS X command line (Factory/Built-in Python installation)''' {{{ cd /Library/Python/2.6/site-packages/ sudo svn co http://code.djangoproject.com/svn/django/tags/releases/1.1.1/django sudo ln -s /Library/Python/2.6/site-packages/django/bin/django-admin.py /usr/bin/django-admin.py }}}
''' OS X via Browser''' [http://www.djangoproject.com/download/1.1.1/tarball/ Download] the tarball. Then double click download.
=== Windows ===
1 - Install Subversion
http://subversion.tigris.org/files/documents/15/45937/Setup-Subversion-1.5.6.msi Subversion
''Choose Apache 2.2 - if you don't know which one you have/will have''
For a different http://subversion.tigris.org/servlets/ProjectDocumentList?folderID=91 version
2 - Install Django 1.1.1 {{{ C:> cd C:Python26Libsite-packages C:Python26Libsite-packages> svn co http://code.djangoproject.com/svn/django/tags/releases/1.1.1/django django }}}
3 - Move admin to scripts directory
Make a copy of django-admin.py (located in djangobin) and put it in C:Python26Scripts
'''ALTERNATIVE'''
requires: http://effbot.org/zone/exemaker.htm Exemaker
{{{ cd C:Python26Libsite-packages svn co http://code.djangoproject.com/svn/django/trunk/django
cd djangobin exemaker django-admin.py }}}
== Your first Django app: A lab note manager ==
=== Django Architecture ===
- Image(django-arch.jpg)
- Image source: http://linfiniti.com/2009/11/geodjango-tutorial/ Linfiniti Geo Blog
=== The final product of this tutorial ===
=== Build project and application ===
'''Restart your terminal for all OSs!! This will ensure it can find django-admin.py'''
Use django and python commands to build the file directories for your project (mysite) and application (lab). First navigate to the Desktop. {{{ #Macs & Linux cd ~/Desktop/ #Windows 7 cd UsersYOUR-ACCOUNT-NAMEDesktop }}}
You can move this project around later to whichever directory you like. Everything will be contained within the project folder.
{{{ django-admin.py startproject mysite cd mysite python manage.py startapp lab }}}
Now tell the project to look for the lab application. Add the application (lab) to ''INSTALLED_APPS'' in settings.py (at the bottom) and don't forget the trailing comma (this is a tuple). {{{
'mysite.lab',
}}}
Now test the success of your project installation by launching the built-in development server. Note: you must be in the ''mysite'' directory. {{{ python manage.py runserver }}}
- Then visiting the site on local host through your web browser.
- e.g. http://127.0.0.1:8000/
You should receive a page that says 'It worked!''
=== Configure database === Edit ''settings.py''
'''MAC/Linux''' (file: mysite/settings.py) {{{ DATABASE_ENGINE = 'sqlite3' DATABASE_NAME = 'lab_db.sqlite3' }}}
'''Win32''' Create a directory for dbase
(file: mysite/settings.py) {{{ DATABASE_ENGINE = 'sqlite3' DATABASE_NAME = 'lab_db.sqlite3' }}}
== Create models for database ==
Django uses an Object Relational Mapper (ORM) to manage your database. You describe the tables in your models file, then they will be converted into SQL create table commands by Django when you syncronized the database. This helps you deploy the application on any system. The SQL commands used will correspond with the database type you declared in your settings file, e.g. MySQL, SQLlite, or PostgreSQL.
(file: mysite/lab/models.py) {{{ from django.db import models
- class LabPost(models.Model):
- title = models.CharField(max_length=150) body = models.TextField() timestamp = models.DateTimeField()
}}}
== Synchronize the database ==
When you synchronize the database, Django will update the database tables and fields according to your models.py file. Note you need to be in the '''project (mysite) directory'''.
{{{ cd mysite python manage.py syncdb }}}
At the prompt create '''superuser''' settings: {{{ Would you like to create one now? (yes/no): yes Username (Leave blank to use 'nico'): pybc E-mail address: [email protected] Password: pybc }}}
If you make a mistake, it can be easiest to delete the SQLlite database file and resynchronize.
=== Configure admin app ===
Add admin to the application list in the settings file (file: mysite/settings.py) {{{
'django.contrib.admin',
}}}
'''Uncomment''' the following two lines in ''urls.py'' to enable access to the admin via the browser's URL:
(file: mysite/urls.py) {{{ # Uncomment TOP from django.contrib import admin admin.autodiscover()
# Uncomment BOTTOM (r'^admin/', include(admin.site.urls)), }}}
The end-product will look something like this:
(file: mysite/urls.py) {{{ from django.conf.urls.defaults import * from django.contrib import admin admin.autodiscover()
- urlpatterns = patterns('',
- (r'^admin/', include(admin.site.urls)),
=== Register lab with the admin === You need to tell the admin which applications it will manage. This is done through the models.py file in each application.
(file mysite/lab/models.py) {{{ # Add to TOP from django.contrib import admin
# Add to BOTTOM admin.site.register(LabPost) }}}
Now re-sync the database: {{{ cd mysite python manage.py syncdb }}}
'''Check it out on localhost, ''' e.g. http://127.0.0.1:8000/
What does the error message tell you
OK ...
Try adding the word admin after the dash in the URL ( http://127.0.0.1:8000/admin).
After you log-in:
{{{ Username: pybc Password: pybc }}}
It should look like this
=== Add some notes ===
Your website is now ready to store data. Try adding notes from the admin interface. Notice how they are listed in the LabPost section. We'll improve the format of the listings next.
=== Pretty up the Admin ===
Let's provide more information about each note in the table of contents. Edit models.py to include the class LabPostAdmin, then register it with admin:
(file: mysite/lab/models.py) {{{ from django.db import models from django.contrib import admin
- class LabPost(models.Model):
- title = models.CharField(max_length=150) body = models.TextField() timestamp = models.DateTimeField()
- class LabPostAdmin(admin.ModelAdmin):
- list_display = ('title', 'timestamp')
admin.site.register(LabPost, LabPostAdmin) }}}
== Configure the Public side (templates) ==
Now let's make the website look like a real application. We don't want users logging on the the admin, that's just for the webmaster and collaborators.
- Create template
- Edit view
- Setup URL
=== 1) Create template ===
Build a template directory to house the templates: {{{ cd mysite mkdir templates cd templates mkdir lab cd lab }}}
Build a template that loops through each LabPost and displays the title, time, and body in HTML tags.
(file: mysite/templates/lab/archive.html) {{{ {% for post in posts %} <h2>{{ post.title }}</h2> <p>{{ post.timestamp }}</p> <p>{{ post.body }}</p> {% endfor %} }}}
Add a reference to the location of your template directory to your project settings file:
(file: mysite/settings.py) {{{ TEMPLATE_DIRS = (
'YOUR_DIR/mysite/templates',
=== 2) Create View ===
The view will send the fields from the database to the html template for display.
(file: mysite/lab/views.py) {{{ from django.template import loader, Context from django.http import HttpResponse from mysite.lab.models import LabPost
- def archive(request):
- posts = LabPost.objects.all() t = loader.get_template("lab/archive.html") c = Context({ 'posts': posts }) return HttpResponse(t.render(c))
}}}
=== 3) Create URL in mysite to redirect to URLconf (urls.py) in lab ===
(file: mysite/urls.py) {{{ # ADD
(r'^lab/', include('mysite.lab.urls')),
}}}
Create generic URLconf for the application
(file: mysite/lab/urls.py) {{{ from django.conf.urls.defaults import * from mysite.lab.views import archive
- urlpatterns = patterns('',
- (r'^$',archive),
=== Adding niceties through templating ===
Now let's make this look more like a website by adding some formatting through css. In a production site you would store the CSS in a stand-alone file, that way you only need to edit one file to make changes throughout the site.
Create a base template for the overall look of the application.
(file mysites/templates/lab/base.html) {{{ <html> <style type="text/css"> body { color: #efd; background: #453; padding: 0 5em; margin: 0 } h1 { padding: 2em 1em; background: #000 url(http://hackerwithin.org/cgi-bin/hackerwithin.fcgi/raw-attachment/wiki/ThwLogo/thwlogo-dark-small.png) no-repeat 0; text-indent:250px} h2 { color: #000; border-top: 2px dotted #000; margin-top: 2em } p { margin: 1em 0 } </style> <body> <h1>My lab notes</h1> {% block content %} {% endblock %} </body> </html> }}}
Now extend the base template with a new customized template for the lab notes. Edit the archive template.
(file mysite/templates/lab/archive.html) {{{ {% extends "lab/base.html" %} {% block content %} {% for post in posts %} <h2>{{ post.title }}</h2> <p>{{ post.timestamp }}</p> <p>{{ post.body }}</p> {% endfor %} {% endblock %} }}}
'''Finished'''