This document provides an introduction to web development with the Django framework. It outlines Django's project structure, how it handles data with models, and its built-in admin interface. It also covers views, templates, forms, and generic views. Django allows defining models as Python classes to represent the database structure. It provides a production-ready admin interface to manage data. URLs are mapped to views, which can render templates to generate responses. Forms validate and display data. Generic views handle common tasks like displaying object lists.

1. Web Development With Django
A Basic Introduction
Ganga L

2. Python Frameworks
 Django
 CherryPy
 Pylons
 Flask
 Bottle
 Tipfy
 Pyramid
 Cubic Web
 GAE framework

3. Outline
 What Is Django?
 Project Structure
 Data Handling
 The Admin Interface
 Django Forms
 Views
 Templates

4. What Is Django?
 High-level framework for rapid web development
 Complete stack of tools
 Data modelled with Python classes
 Production-ready data admin interface, generated dynamically
 Elegant system for mapping URLs to Python code
 Generic views’ to handle common requests
 Clean, powerful template language
 Components for user authentication, form handling, caching . . .

5. Creating Projects & Apps
 Creating a project:
django-admin.py startproject mysite
 Creating an app within a project directory:
cd mysite
./manage.py startapp poll

6. Project Structure
 A Python package on your PYTHONPATH
 Holds project-wide settings in settings.py
 Holds a URL configuration (URLconf) in urls.py
 Contains or references one or more apps

7. App
 A Python package on your PYTHONPATH
(typically created as a subpackage of the project itself)
 May contain data models in models.py
 May contain views in views.py
 May have its own URL configuration in urls.py

8. Up & Running
 Set PYTHONPATH to include parent of your project directory
 Define new environment variable DJANGO_SETTINGS_MODULE,
setting it to project settings (mysite.settings)
 3 Try running the development server:
/manage.py runserver

9. Creating The Database
 Create database polls in youe database
 Sync installed apps with database:
./manage.py syncdb

10. Create Project
 Create Project mysite
mysite/
manage.py
mysite/
__init__.py
settings.py
urls.py

11. Create Application
 python manage.py startapp polls
polls/
__init__.py
models.py
tests.py
views.py

12. Create Models
from django.db import models
class Poll(models.Model):
question = models.CharField(max_length=200)
pub_date = models.DateTimeField('date published')
class Choice(models.Model):
poll = models.ForeignKey(Poll)
choice_text = models.CharField(max_length=200)
votes = models.IntegerField(default=0)

13. The Data Model
 A description of database layout, as a Python class
 Normally represents one database table
 Has fields that map onto columns of the table
 Many built-in field types
 CharField, TextField
 IntegerField, FloatField, DecimalField
 DateField, DateTimeField, TimeField
 EmailField, URLField
 ForeignKey . . .

14. Installed App
INSTALLED_APPS = (
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'polls',
)
python manage.py syncdb

15. Registering Models in Admin
 In admin.py in the Poll app:
from django.contrib import admin
from mysite.polls.models import Poll
admin.site.register(Poll)

16. In urls.py:
from django.conf.urls import patterns, include, url
from django.contrib import admin
admin.autodiscover()
urlpatterns = patterns('',
url(r'^admin/', include(admin.site.urls)),
)

17. Generic Views
 Provide ready-made logic for many common tasks:
 Issuing a redirect
 Displaying a paginated list of objects
 Displaying a ‘detail’ page for a single object
 Yearly, monthly or daily listing of date-based
objects
 ‘Latest items’ page for date-based objects
 Object creation, updating, deletion (with/without
authorisation)

18. Generic Views Example
 views.py
def index(request):
return HttpResponse("Hello, world. You're at the poll index.")
 Url.py
from django.conf.urls.defaults import *
from polls import views
urlpatterns = patterns('',
url(r'^$', views.index, name='index')
)
 Main URL.py
from django.conf.urls import patterns, include, url
from django.contrib import admin
admin.autodiscover()
urlpatterns = patterns('',
url(r'^polls/', include('polls.urls')),
url(r'^admin/', include(admin.site.urls)),
)

19. Creating & Saving Objects
 Invoke constructor and call save method:
 call create method of Club model manager:
poll = Poll(question='what is your DOB? ', year='1986)
poll.save()
Poll.objects.create(question='what is your DOB? ', year='1986)

20. View Function
 Takes an HTTPRequest object as a parameter
 Returns an HTTPResponse object to caller
 Is associated with a particular URL via the URLconf

21. HTTP Response
from datetime import date
from django.http import HttpResponse
def today(request):
html = '<html><body><h2>%s</h2></body></html>' % date.today()
return HttpResponse(html)
from django.shortcuts import render_to_response
From mysite.polls.models import Poll
def poll_details(request):
today = date.today()
poll_data = Poll.objects.all()
return render_to_response('clubs.html', locals(), context_instance =
RequestContext(request))

22. Templates
 Text files containing
 Variables, replaced by values when the template
is rendered[
 {{ today }}
 Filters that modify how values are displayed
 {{ today|date:"D d M Y" }}
 Tags that control the logic of the rendering
process
 {% if name == "nick" %}
 <p>Hello, Nick!</p>
 {% else %}
 <p>Who are you?</p>
 {% endif %}

23. Template Example
settings.py
TEMPLATE_DIRS = (
os.path.join(os.path.dirname(__file__), 'templates'),
)
templates/club/club_list.html
{% extends "base.html" %}
{% block title %}Clubs{% endblock %}
{% block content %}
<h1>Clubs</h1>
<ol>
{% for club in clubs %}
<li>{{ club }}</li>
{% endfor %}
</ol>
{% endblock %}

24. Django Forms
 A collection of fields that knows how to validate itself and display
itself as HTML.
 Display an HTML form with automatically generated form widgets.
 Check submitted data against a set of validation rules.
 Redisplay a form in the case of validation errors.
 Convert submitted form data to the relevant Python data types.

25. Django Model Forms
from django.forms import ModelForm
import mysite.polls.models import Poll
class PollForm(ModelForm):
class Meta:
model = Pole

26. A Basic Django Forms

27. Standard Views.py

28. Standard Views.py

29. Standard Views.py

30. Easy Views.py

31. Easy Views.py

32. Summary
 We have shown you
 The structure of a Django project
 How models represent data in Django applications
 How data can be stored and queried via model
instances
 How data can be managed through a dynamic
admin interface
 How functionality is represent by views, each
associated
with URLs that match a given pattern
 How views render a response using a template

33. Thank You