Python & Django: Fast and easy web application development

Python & Django Fast and easy web application development 4developers'09 Marcin Mierzejewski // www.zenzire.com

Agenda Python: Django: • features • history • examples • features • architecture • example

Python Guido van Rossum, 1990 Interpreter Paradigms: • structural • object oriented • functional Readability

Python. Open Source Platforms: • Windows • Linux • ... Implementation: CPython, JPython, IronPython, PyPy, Psyco

Interpreter ~$ python >>> print 'hello 4developers' hello 4developers >>> text = 'Python & Djnago' >>> print text[0] P >>> print text[:6], text[-6:] Python Django >>> print text[9:11] * 3 DjDjDj

Structural a = 10 if a > 5: print 'bigger' else: print 'lesser' for i in ['A', 'be', 3, 4.5, True]: print i

Object oriented class A: def function_a(self): print 'A' class B(A): def function_b(self): self.function_a() print 'B' a = A() a.function_a() ----------> A b = B() b.function_b() ----------> A B

Functional def factorial(x): if x == 0: return 1 else: return x * factorial(x-1) factorial(10) factorial = lambda x:(1 if x==0 else x * factorial(x-1)) factorial(10)

Django Framework to easy and fast develop web application

History 2003: Kansas, USA 2005: BSD & v0.90 2006: v0.95 2007: v0.96 2008: Fundation & v1.0 2009: EuroDjango

Features Documentation HTTP Server ORM URL dispatcher Templates Interactive Console

Features Administration Panel Forms Middleware & Sygnals Authentication & Authorization i18n i L10n Cache

Architecture MVC (MTV ) Model Template View Model - data View - logic Template - presentation

Architecture Web Browser Template URL View Model Database

Model Web Browser Template URL View Model Database

Model SQL Free ORM Relations API

Model class Category(models.Model): name = models.CharField(max_length=200) slug = models.SlugField(unique=True) class Entry(models.Model): title = models.CharField(max_length=200) slug = models.SlugField(unique=True) content = models.TextField() data = models.DateTimeField(default=datetime.now) categories = models.ManyToManyField(Category)

Model API >>> category = Category(slug='django', name='Django') >>> category.save() >>> print category.name U'Django' >>> categories = Category.objects.all() >>> categories = Category.objects.filter(slug='django') >>> categories [<Category: Category object>] >>> entry = Entry(slug='hello',title='Hello',content='') >>> entry.save() >>> entry.categories.add( categories[0] ) >>> print entry.categories.all() [<Category: Category object>]

View Web Browser Template URL View Model Database

View def entry_list(request): entries = Entry.objects.all()[:5] return render_to_response('list.html', \\ {'entries': entries}) def entry_details(request, slug): entry = get_object_or_404(Entry, slug = slug) return render_to_response('details.html', \\ {'entry': entry})

Template Web Browser Template URL View Model Database

Template {{ variables }}, {% tags %} i {{ variable|filter }} <html> <head><title>My blog</title></head> <body> {% for entry in entries %} <h1>{{ entry.title|upper }}</h1> {{ entry.content }}<br/> Published {{ entry.data|date:\"d F Y\" }}, <a href=”/{{ entry.slug }}/”>link</a>. {% endfor %} </body> </html>

URL Web Browser Template URL View Model Database

URL # http://mywebsite.com/4developers/ (r'^(?P<slug>[-\\w]+)/$', 'blog.views.entry_details'), # http://mywebsite.com/ (r'^$', 'blog.views.entry_list'),

Architecture Web Browser Template URL View Model Database

Example Entry List Entry Details Administrator Panel Users

Project # django-admin.py startproject project project/ __init__.py manage.py settings.py [1] urls.py [2] [1] [2] DATABASE_ENGINE from django.contrib import admin DATABASE_NAME admin.autodiscover() INSTALLED_APPS = ( ... (r'^admin/(.*)', include('admin.site.root')) 'django.contrib.admin'

Tables project# manage.py syncdb Creating table auth_permission Creating table auth_group Creating table auth_user Creating table auth_message Creating table django_content_type Creating table django_session Creating table django_site ......................... project# manage.py runserver Validating models... 0 errors found Django version 1.0-final-SVN-unknown, .......... Development server is running at http://127.0.0.1:8000/ Quit the server with CTRL-BREAK.

Administration Panel http://127.0.0.1:8000/admin/

Blog project# manage.py startapp blog project/ settings.py ← INSTALLED_APPS = ( ... ... 'blog',) blog/ __init__.py models.py views.py

models.py project/blog/models.py class Entry(models.Model): title = models.CharField(max_length=200) slug = models.SlugField(unique=True) content = models.TextField() data = models.DateTimeField(default=datetime.now) def __unicode__(self): return u'%s' % self.title admin.site.register(Entry)

models.py project# manage.py syncdb project# manage.py runserver

views.py project/blog/views.py def entry_list(request): entries = Entry.objects.all().order_by('-data')[:5] return render_to_response('list.html', \\ {'entries': entries}) def entry_details(request, slug): entry = get_object_or_404(Entry, slug = slug) return render_to_response('details.html', \\ {'entry': entry})

urls.py project/urls.py: (r'^(?P<slug>[-\\w]+)/$', 'blog.views.entry_details'), (r'^$', 'blog.views.entry_list'),

Templates project/template/list.html <html> <body> {% for entry in entries%} <h1>{{ entry.title|upper }}</h1> {{ entry.content }}<br> Published {{ entry.data|date:\"d F Y\" }}<br/> <a href=\"/{{ entry.slug }}/\">Link</a> {% endfor %} </body> </html> project/template/details.html <html> <body> <h1>{{ entry.title|upper }}</h1> {{ entry.contentc }}<br> Published {{ entry.data|date:\"d F Y\" }}<br/> </body> </html>

Done http://127.0.0.1:8000/ http://127.0.0.1:8000/4developers-2008

Statistics views.py + models.py + settings.py + urls.py = 30 LoC list.html + details.html = 17 LoC

Thank You For more details: http://www.djangoproject.com/

Pictures http://www.flickr.net/photos/ecstaticist/1340787730/ http://www.flickr.net/photos/schoffer/196079076/ http://www.flickr.net/photos/kogakure/2225768345/ http://www.flickr.net/photos/hotsaucejane/2385963623/ http://www.flickr.net/photos/mag-cafe/163556150/ http://www.flickr.net/photos/pauliogeordio/2301563705/ http://www.flickr.net/photos/origomi/345911878/ http://www.flickr.net/photos/ravages/2831688538/ http://www.flickr.net/photos/dizzygirl/125328389/

Python & Django: Fast and easy web application development

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