There are three levels to creating software: computer science, software engineering, and this thing that people do with Java inside enterprises.

After using my Django CAS authentication module for a while, I decided to make a couple improvements.

The biggest improvement is that instead of modifying code in the CAS module itself to set your CAS address and do things like custom User field population, all this stuff can now be configured in your settings file.

Another improvement is that CAS authentication now works for the bundled admin interface. Since the administration interface does not account for an authentication backend that doesn't know the user's password, this makes the login form useless. The CAS module will now intercept requests to the administration interface and do the proper authentication routine if necessary, never showing the login form (which doesn't make sense for CAS). Intercepting requests, you ask? Yes, that means the CAS module is now middleware. Actually it's middleware, a couple views, and an authentication backend.

So here's how to use it now...

Get cas_middleware.tar.gz.

Extract it in django/contrib/. The code will be located at django/contrib/cas/. Is this a valid place to install third-party middleware? It's not really clear. Just do it anyway.

Now add it to the middleware and authentication backends in your settings. Make sure you also have the authentication middleware installed. Here's what mine looks like:

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.cas.middleware.CASMiddleware',
    'django.middleware.doc.XViewMiddleware',
)

AUTHENTICATION_BACKENDS = (
    'django.contrib.cas.backend.CASBackend',
)

You can now configure the CAS module in the same settings file. Here are the possible options, most of which can be safely ignored:

• CAS_SERVICE_URL: This is the only setting you must explicitly define. Set it to the base URL of your CAS source.
• CAS_POPULATE_USER: A callable or the location of a callable. When a user logs in and is missing name and email attributes in the database, this will be called with their User model instance. Default is None (do nothing).
• CAS_ADMIN_PREFIX: The URL prefix of the Django administration site. If undefined, the CAS middleware will just check the view being rendered to see if it lives in django.contrib.admin.views. The method is a little evil, but it works.
• CAS_LOGIN_URL: The URL where you bound django.contrib.cas.views.login. If undefined, assume /accounts/login/.
• CAS_LOGOUT_URL: The URL where you bound django.contrib.cas.views.logout. If undefined, assume /accounts/logout/.
• CAS_REDIRECT_URL: Where to send a user after logging in or out if there is no referrer and no next page set. Default is /.
• CAS_REDIRECT_FIELD_NAME: The name of the GET parameter in which to store the page URL to send the user to after logging in. Default is next.

Need an example? Here's what my CAS settings look like:

CAS_SERVICE_URL = 'https://login.case.edu/cas/'
CAS_POPULATE_USER = 'present.utils.populate_user'

And the callable that lives at present.utils.populate_user (notice this code lives in my project instead of tinkering with the CAS module) looks like this:

def populate_user(user):
    try:
        ldap = LDAP()
        person = ldap.filter_one_by(uid=user.username)
    except:
        if not user.email:
            user.email = "%s@case.edu" % user.username
    else:
        # If it succeeds, update their User entry
        user.email = person.mail[0]
        user.first_name = fix_case(person.givenName[0])
        user.last_name = fix_case(person.sn[0])

( LDAP and fix_case also live in my utils module).

Finally, make sure your project knows how to log users in and out by adding these to your URLconf:

(r'^accounts/login/$', 'django.contrib.cas.views.login'),
(r'^accounts/logout/$', 'django.contrib.cas.views.logout'),

Users should now be able to log into your site, and staff into the administration interface, using CAS 1.0.

A while ago Chris added a login method to the CAS module in CaseClasses. It returns a mechanize Browser object so that you can programmatically surf the web as if you had logged into CAS in a real web browser.

CaseClasses also has a Codes module that has the abbreviated codes for majors, departments, and buildings. I combined these two features to tackle the Building codes project on the Case Wiki.

P.S.: There is a MediaWiki API that would normally be used to do this kind of stuff, but according to Greg, editing is not fully functional yet.

Think you could add a lot to the wiki with some automated task? Here's how it was done.

First, you'll need mechanize and CaseClasses:

$ sudo easy_install mechanize
$ sudo easy_install http://opensource.case.edu/svn/CaseClasses/python/trunk

Now log into CAS with mechanize:

import Case
from getpass import getpass

username = 'bmb12'
password = getpass() # Enter a password without echoing

cas = Case.CAS()
browser = cas.login(username, password)

You can open any page with browser and interact with it as a logged in Case user. So let's go to the Case Wiki and log in:

browser.set_handle_robots(False)
browser.open("http://wiki.case.edu")
browser.follow_link(text_regex='Log In')

Editing can be done like so:

browser.open("http://wiki.case.edu/User:Brian.Beck")

browser.follow_link(text='Edit this page')
browser.select_form(name='editform')
browser['wpTextbox1'] += " Also, this guy sucks!"
browser.submit()

Automating the building code edits was done like so:

for code, name in Case.Codes.buildings.iteritems():
    url = "http://wiki.case.edu/%s" % name.replace(' ', '_')
    try:
        browser.open(url)
    except:
        print "Didn't find %r." % name
    else:
        browser.follow_link(text='Edit this page')
        browser.select_form(name='editform')
        source = browser['wpTextbox1']
        add_text = "The building code for %s is [[building code:=%s]].\r\n"
        add_text %= (name, code)
        if 'code:=' not in source:
            insert_at = source.find('{{Building')
            if insert_at != -1:
                new_source = source[:insert_at] + add_text + source[insert_at:]
            else:
                new_source = source + add_text
            browser['wpTextbox1'] = new_source
            browser.submit()
            print "Added building code for %r." % name

Happy automating!

g = geocoders.Google(resource='maps')

g = geocoders.Google(resource='maps', output_format='js')

g = geocoders.Google(domain='maps.google.co.uk', resource='maps', output_format='js')

sudo easy_install geopy

>>> from dmath import *
>>> from decimal import Decimal as D, getcontext
>>> getcontext().prec = 50
>>> asin(D(1))
Decimal("1.5707963267948966192313216916397514420985846996876")
>>> golden_ratio()
Decimal("1.6180339887498948482045868343656381177203091798058")