django framework

1. Python Django
Web Development
Chapter Two
BY:Eng Mohamed Ahmed Mohamed

2. Function vs. Class Views
 Django allows two styles of views – functions or
class based views
 Functions – take a request object as the first
parameter and must return a response object
 Class based views – allow CRUD operations with
minimal code. Can inherit from multiple generic
view classes (i.e. Mixins)

3. Sample – As Class Based
View
from .models import Question
from django.views.generic import ListView
class QuestionList(ListView):
model = Question
context_object_name = ‘questions’

4. urls.py
 Defines routes to send urls to various views
 Can use regular expressions
 Extract parameters from a url and pass to the view as a
named parameter:
r(‘^question/(?P<question_id>d+)/$’,’views.question_detail’)
 Extensible – urls.py can include additional url files from
apps:
r(‘^question/’,include(question.urls))

5. Views

6. Working with User Input
Major Steps:
1. Adding an HTML form to our template.
2. Editing the application URLconf.
3. Adding a new view function that processes
user input.

7. Request & Response
 Request object encapsulate the request and provide access to a
number of attributes and methods for accessing cookies, sessions,
the logged in user object, meta data (i.e environment variables),
 Response objects are returned to the browser. Can set content
type, content length, response does not have to return HTML or a
rendered template
 Special response types allow for common functionality:
HttpResponeRedirect
Http404
HttpStreamingResponse

8. Quick CRUD Operations with
Generic Views
 ListView
 UpdateView
 CreateView
 If Model is specified, automagically creates a
matching ModelForm
 Form will save the Model if data passes validation
 Override form_valid() method to provide custom
logic (i.e sending email or setting additional fields)

9. Debugging Hints
The command line you use to run the development server often shows helpful
error messages
Django and the development server support hot-swap; you usually do not need to
restart the server when you change the code. Hot swap works much better on
the development server than in most servers that claim to support it. However,
it doesn’t work fif you change url mappings (see below). Also, note that your
browser may cache responses, so you may need to reload several times to see
changes.

10. Django Extras
 CRSF Middleware – enabled by default. Include template
tag in all forms:
{%csrf_token%}
 Authentication
 Caching
 Sessions
 Messages
 Email
 Logging

11. Cross-Site Request Forgery
Django comes with a data-preserving feature
that disallows POSTs which are not secure
against cross-site request forgery (CSRF)
attacks.
You can read more about CSRF at the following
website:
https://docs.djangoproject.com/en/dev/ref/
contrib/csrf/

12. Cross-Site Request Forgery
For our simple application, two fixes:
1. Add a CSFR token ({% csrf_token %} to forms
that POST back to your site
2. Send the request context instance to the token
via the template.

13. Thank You
Question
And
Answers