Advanced Django2929

7/30/2019 Advanced Django2929

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Advanced Django

Simon Willisonhttp://simonwillison.net/

PyCon UK, 8th September 2007
http://simonwillison.net/http://simonwillison.net/


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Unit testingnewforms

Ajax

And if we have time... OpenID

Todays topics


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Unit testing


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Hard core TDD

Test Driven Development as taught by Kent

BeckWrite new code only if an automated test hasfailed

Revolutionises the way you write codePretty hard to adopt


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I dont do test drivendevelopment. I do stupidity

driven testing... I wait until I dosomething stupid, and then write

tests to avoid doing it again.

Titus Brown


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What NOT to do

No matter how tough the deadline, don't letyour test suite start breaking and say Ill fix itlater

This will hurt. A lot.


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Testing in Django

Testing web apps is HARD, but Django helps outwith a bunch of features:

Fixtures

Doctests

Test ClientE-mail capture


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Doctests

Used by Django for both ORM testing andgenerated documentation

You are encouraged to add them to your ownmodels.py

manage.py test to execute them

Great for regression tests - just copy and pastefrom an interpreter session


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>>> p = Person(name="Bob", dob=date(1980, 1, 1))

>>> p.age(date(1980, 1, 1))0>>> p.age(date(1979, 1, 1))-1>>> p.age(date(1981, 6, 1))1>>> p.age(date(2000, 1, 1))20>>> p.age(date(1999, 12, 31))19>>> p2 = Person(name="Barry", dob=date(1981, 5, 5))>>> p2.age(date(1981, 5, 5))0>>> p2.age(date(1982, 5, 4))0

>>> p2.age(date(1982, 5, 5))1>>> p2.age(date(1982, 5, 6))1


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class Person(models.Model):"""... tests here ...

"""name = models.CharField(maxlength=100)dob = models.DateField()def age(self, age=False):

return 1


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$ python manage.py test

...F

======================================================================

FAIL: Doctest: peopleage.models.Person

----------------------------------------------------------------------

Traceback (most recent call last):

File "/usr/lib/python2.5/site-packages/django/test/_doctest.py", line 2161, in runTest

raise self.failureException(self.format_failure(new.getvalue()))

AssertionError: Failed doctest test for peopleage.models.PersonFile "/home/simon/Projects/Django/oscon07/peopleage/models.py", line 4, in Person

----------------------------------------------------------------------

File "/home/simon/Projects/Django/oscon07/peopleage/models.py", line 7, inpeopleage.models.Person

Failed example:

p.age(date(1980, 1, 1))

Expected:0

Got:

1


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def age(self, age=False):

if not age:age = date.today()delta = age - self.dobreturn int(math.floor(delta.days / float(365)))


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File "/home/simon/Projects/Django/oscon07/peopleage/models.py", line 16,in peopleage.models.Person

Failed example:

p.age(date(1999, 12, 31))Expected:

19Got:

20


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def age(self, age=False):

if not age:

age = date.today()

years = age.year - self.dob.yearthis_year_birthday = self.dob.replace(year=age.year)

birthday_has_passed = age >= this_year_birthday

if not birthday_has_passed:

years = years - 1

return years


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Fixtures

Its useful to be able to clear and populate yourtest database in between tests

Fixtures let you do that (they also let youpopulate your database with real data when you

deploy your application)


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Denormalisation


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Normalised data is

for sissies

Cal Henderson


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A forum, where each thread can have oneor more replies

Maintain a separate counter in the Forumtable of number of replies, to speed upqueries


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class Thread(models.Model):subject = models.CharField(maxlength=100)

num_replies = models.IntegerField(default=0)

class Reply(models.Model):thread = models.ForeignKey(Thread)message = models.TextField()


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[{ "model": "forum.thread","pk": "1",

"fields": {"num_replies": 0,"subject": "First thread" }

},{ "model": "forum.thread","pk": "2",

"fields": {"num_replies": 1,"subject": "Second thread" }

},{ "model": "forum.reply","pk": "1","fields": {

"thread": 2,"message": "First post!1" }

}]


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from django.test import TestCase

from models import Thread, Reply

class ThreadCountTestCase(TestCase):fixtures = ['threadcount.json']

def test_add_reply(self):thread = Thread.objects.get(pk=2)

self.assertEqual(thread.num_replies, 1)thread.reply_set.create(message="Another post")

thread = Thread.objects.get(pk=2)self.assertEqual(thread.reply_set.count(), 2)self.assertEqual(thread.num_replies, 2)

def test_delete_reply(self):thread = Thread.objects.get(pk=2)

self.assertEqual(thread.num_replies, 1)

Reply.objects.get(pk=1).delete()thread = Thread.objects.get(pk=2)

self.assertEqual(thread.reply_set.count(), 0)self.assertEqual(thread.num_replies, 0)


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======================================================

FAIL: test_add_reply (forum.tests.ThreadCountTestCase)----------------------------------------------------------------------Traceback (most recent call last):

File "/home/simon/Projects/Django/oscon07/forum/tests.py", line 16, intest_add_reply

self.assertEqual(thread.num_replies, 2)AssertionError: 1 != 2

======================================================

FAIL: test_delete_reply (forum.tests.ThreadCountTestCase)----------------------------------------------------------------------Traceback (most recent call last):

File "/home/simon/Projects/Django/oscon07/forum/tests.py", line 23, intest_delete_reply

self.assertEqual(thread.num_replies, 0)AssertionError: 1 != 0

----------------------------------------------------------------------


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class Reply(models.Model):...def save(self):

super(Reply, self).save()

self.thread.num_replies = self.thread.reply_set.count()self.thread.save()

def delete(self):super(Reply, self).delete()self.thread.num_replies = self.thread.reply_set.count()self.thread.save()


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.......

-----------------------------------------------------------Ran 7 tests in 0.372s

OK


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Djangos TestClient lets you simulate a browserinteracting with your site

It also provides hooks in to the underlyingapplication, so you can test against the template

and context that was used to generate a page

Testing views


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from django.test import TestCase

class RegistrationTest(TestCase):def test_slash(self):

response = self.client.get('/register')self.assertEqual(response.status_code, 301)

response = self.client.get('/register/')self.assertEqual(response.status_code, 200)

def test_register(self):

response = self.client.get('/register/')self.assertEqual(response.template[0].name, 'register.html')

self.assertTemplateUsed(response, 'register.html')


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def test_signup_done_page(self):self.assertEqual(len(mail.outbox), 0)data = {

'email': '[email protected]', 'username': 'example','firstname': 'Example', 'lastname': 'User','password': 'password1', 'password2': 'password1',

}response = self.client.post('/signup/', data)self.assertEquals(response.status_code, 302)self.assertEquals(response['Location'], '/welcome/')# Check that the confirmation e-mail was sentself.assertEqual(len(mail.outbox), 1)sent = mail.outbox[0]

self.assertEqual(sent.subject, 'Welcome to example.com')
mailto:[email protected]:[email protected]:[email protected]


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http://www.djangoproject.com/documentation/testing/

More on testing with Django:
http://www.djangoproject.com/documentation/testing/http://www.djangoproject.com/documentation/testing/


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newforms


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Display a form

User fills it in and submits it

Validate their entered data

If errors, redisplay form with previouslyentered data and contextual error messages

Continue until their submission is valid

Convert submission to appropriate Python types

The perfect form


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Manipulators


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Manipulatorsnewforms


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from django import newforms as forms

class UserProfileForm(forms.Form):name = forms.CharField(max_length=100)email = forms.EmailField()bio = forms.CharField(widget=forms.Textarea)dob = forms.DateField(required=False)receive_newsletter = forms.BooleanField(required=False)

Forms are declarative


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def create_profile(request):if request.method == 'POST':

form = UserProfileForm(request.POST)if form.is_valid():

# ... save the users profilereturn HttpResponseRedirect('/profile/saved/')

else:form = UserProfileForm()

return render_to_response('profile.html', {'form': form})

Simple form handling view


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form = UserProfileForm(initial = {

'name': 'Simon Willison','email': '[email protected]',

})

Initial data
mailto:[email protected]:[email protected]:[email protected]


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ul.errorlist { color: red; }

...{{ form.as_p }}...

Simple template


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Output

Name:

Email:

Bio:

Dob:

Receive newsletter:


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Output

Name:

Email:

Bio:

Dob:

Receive newsletter:


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Name:

Email:

Bio:

Dob:

Receive newsletter:

Output


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Custom validationfrom django import newforms as forms

from django.newforms.util import ValidationError

class UserProfileForm(forms.Form):name = forms.CharField(max_length=100)

email = forms.EmailField()bio = forms.CharField(widget=forms.Textarea)

dob = forms.DateField(required=False)receive_newsletter = forms.BooleanField(required=False)

def clean_email(self):if self.cleaned_data['email'].split('@')[1] == 'hotmail.com':

raise ValidationError, "No hotmail.com emails, please."


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Custom validationfrom django import newforms as forms

from django.newforms.util import ValidationError

class UserProfileForm(forms.Form):name = forms.CharField(max_length=100)

email = forms.EmailField()bio = forms.CharField(widget=forms.Textarea)

dob = forms.DateField(required=False)receive_newsletter = forms.BooleanField(required=False)

def clean_email(self):if self.cleaned_data['email'].split('@')[1] == 'hotmail.com':

raise ValidationError, "No hotmail.com emails, please."


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Custom rendering

Email: {{ form.email }}{{ form.email.errors }}

Your e-mail address.

...


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Model shortcuts

DRY: Youve already declared your models; youshouldnt have to repeat yourself in your forms

UserForm = form_for_model(User)

###############################

page = Page.objects.get(pk=1)PageForm = form_for_instance(page)

form = PageForm(request.POST)...if form.is_valid(): form.save()


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http://www.djangoproject.com/documentation/newforms/

django/trunk/tests/regressiontests/forms/tests.py

Full documentation:
http://www.djangoproject.com/documentation/testing/http://www.djangoproject.com/documentation/testing/http://www.djangoproject.com/documentation/testing/http://www.djangoproject.com/documentation/testing/http://www.djangoproject.com/documentation/testing/http://www.djangoproject.com/documentation/testing/


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Ajax


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First things first

If you're going to do Ajax, you need a JavaScriptlibrary

You could use Yet Another XMLHttpRequestabstraction... but the popular libraries offer fantasticconvenience

Good libraries include YUI, Dojo, MochiKit and(controversial) Prototype...


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.. and jQuery

I'm going to be using jQuery

Almost everything is done in terms of CSSselectors and chained methods

It looks like a gimmick, but it isn't

http://simonwillison.net/2007/Aug/15/jquery/
http://simonwillison.net/2007/Aug/15/jquery/http://simonwillison.net/2007/Aug/15/jquery/http://simonwillison.net/2007/Aug/15/jquery/


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Ajax formats...

Django has great support for any and every Ajax

formatHTML fragments

XML

JSON


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Username available?

from django.contrib.auth.models import User

def check_username(request):

reply = ""username = request.GET.get('username', '')

if username:

if User.objects.filter(username=username).count():

reply = 'Unavailable'

else:reply = 'Available'

return HttpResponse(reply)


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jQuery('span#msg').load('/check_username/?username=' + input.val()

);


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$('span#msg').load('/check_username/?username=' + input.val()

);


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var input = $('input#id_username')input.keyup(function() {


);});


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$(document).ready(function() {var input = $('input#id_username')input.keyup(function() {


);});

});


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$(function() {var input = $('input#id_username')input.keyup(function() {


);});

});


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Recycling server-sideform validation


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from django import newforms as forms

class ContactForm(forms.Form):subject = forms.CharField(max_length=100)message = forms.CharField(widget=forms.Textarea())sender = forms.EmailField()


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def validate_contact(request):"Validate post data, return errors as json"form = ContactForm(request.POST)if (request.GET.has_key('field')):

# Validate a single field

errors = form.errors[request.GET['field']]else:

errors = form.errorsreturn JsonResponse({

'valid': not errors,'errors': errors

})


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from django.utils import simplejson

class JsonResponse(HttpResponse):

def __init__(self, data):HttpResponse.__init__(

self, simplejson.dumps(data),mimetype='application/json'

)


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function validateInput(input) {

$.post('/contact/validate/?field=' + input.attr('id').replace('id_', ''),

$('form').formToArray(), function(data) {

var json = eval('(' + data + ')');

showErrors(input, json.errors);

}

);}

$(function() {

$(':input').blur(function() {

validateInput($(this));

});

});


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function relatedErrorList(input) {

var prevUL = $(input).parent().prev();

if (prevUL && prevUL.attr('class') == 'errorlist') {return prevUL;

}

var errorlist = $('');

input.parent().before(errorlist);

return errorlist;

}

function showErrors(input, errors) {

var errorlist = relatedErrorList(input);

errorlist.empty();

$.each(errors, function(i, error) {

errorlist.append('' + error + '');});

}


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Django often gets marked down in framework

comparisons due to the lack of built in Ajaxsupport

Personally I think that shipping without a

recommended library is a feature, not a bug

Django philosophy


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(bonus section)


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What is OpenID?


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OpenID is adecentralised

mechanism for Single Sign On


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An OpenID is a URL

http://simonwillison.myopenid.com/

http://simonwillison.net/

http://swillison.livejournal.com/

http://openid.aol.com/simonwillison
http://openid.aol.com/simonwillisonhttp://swillison.livejournal.com/http://simonwillison.net/http://openid.aol.com/simonwillisonhttp://openid.aol.com/simonwillisonhttp://swillison.livejournal.com/http://swillison.livejournal.com/http://simonwillison.net/http://simonwillison.net/http://simonwillison.myopenid.com/http://simonwillison.myopenid.com/


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How it works

You enter your OpenID on a site (instead of the

usual username and password)It redirects you back to your OpenID provider

They authenticate you in some way

They redirect you back to the original site


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Simple registration(an optional but useful extension)


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Your preferred username

Your e-mail address

Your first and last name

Your date of birth

Your language, country and timezone

Consumers can also ask...


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How do you use

OpenID in a Djangoapplication?


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Use the JanRain OpenID library

Pretty much a reference implementation for theOpenID spec

Well written, well tested but takes a while to getthe hang of

www.openidenabled.com/openid/libraries/python/

The hard way
http://www.openidenabled.com/openid/libraries/python/http://www.openidenabled.com/openid/libraries/python/http://www.openidenabled.com/openid/libraries/python/


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The easy way

Use django-openid

A simple wrapper around JanRain

A middleware component, some models and afew pre-written views

http://code.google.com/p/django-openid/
http://code.google.com/p/django-openid/http://code.google.com/p/django-openid/http://code.google.com/p/django-openid/


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Installation

Add 'django_openidconsumer' to yourINSTALLED_APPS setting

manage.py syncdb

Add the OpenIDMiddleware to yourMIDDLEWARE_CLASSES setting

Add the views to your URLconf


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In urls.py

...

(r'ôpenid/$',

'django_openidconsumer.views.begin'),(r'ôpenid/complete/$','django_openidconsumer.views.complete'),

(r'ôpenid/signout/$',

'django_openidconsumer.views.signout'),...


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request.openid

The middleware adds an openid property to theDjango request object

If the user is not signed in, this will be None

Otherwise, it will be an OpenID object; the str()

representation will be the OpenID (or userequest.openid.openid)


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def example_view(request):if request.openid:

return HttpResponse("OpenID is %s" % escape(request.openid))else:

return HttpResponse("No OpenID")


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The module supports users signing in with morethan one OpenID at a time

request.openids provides a list of allauthenticated OpenIDs

request.openid merely returns the mostrecent from this list

request.openids

F i l i i


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(r'^openid/$', 'django_openidconsumer.views.begin', {

'sreg': 'email,nickname'}),

def example_sreg(request):if request.openid and request.openid.sreg.has_key('email'):

return HttpResponse("Your e-mail address is: %s" % escape(

request.openid.sreg['email']))

else:

return HttpResponse("No e-mail address")

For simple registration


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django_openidauth, providing tools to associate

OpenIDs with existing django.contrib.authaccounts

django_openidserver, to make it easy to provide

OpenIDs for users of your Django application

Coming soon


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More information

http://openid.net/

Also home to the OpenID mailing lists

http://www.openidenabled.com/

http://simonwillison.net/tags/openid/

http://code.google.com/p/django-openid/
http://code.google.com/p/django-openid/http://simonwillison.net/tags/openid/http://www.openidenabled.com/http://code.google.com/p/django-openid/http://code.google.com/p/django-openid/http://simonwillison.net/tags/openid/http://simonwillison.net/tags/openid/http://www.openidenabled.com/http://www.openidenabled.com/http://openid.net/http://openid.net/


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Thank you!

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