Django

Django Tech Talk
By Amanpreet Singh
amanpreet.singh1@hindustantimes.com

Why Django?
● Fully loaded.
● Reassuringly secure.
● Exceedingly scalable.
● Incredibly versatile.
● Ridiculously fast.

Django at a
glance.
● Design your model
● Enjoy the free API
● A dynamic admin
interface
● Design your URLs
● Write your views
● Design your templates

IS IT MTV OR MVC??
What do you think?

The model layer
❖ Models
❖ QuerySets
❖ Migrations
❖ Managers

Models
❖ Setup
❖ Field Options(primary_key, null, blank)
❖ Relationships
❖ Backward Relationship( How it works?)
❖ Field Name Restrictions
❖ Meta Options

Models Cont.
❖ Model Attributes (Manager)
❖ Model Methods
❖ Model Inheritance
➢ Abstract Base Class
➢ Derived Class
➢ Multi-table Inheritance
➢ Multiple Inheritance

QuerySets
It can be filtered, sliced etc generally without actually hitting
the database.
No DB activity actually occurs until you do something to
evaluate queryset.

Some Methods
that return new
QuerySet
● filter( )
● all( )
● select_related( )
● values( )
● values_list ( )
● exclude( )
● only( )
● order_by( )

Some Methods
that do not
return new
QuerySet
● get ( )
● get_or_create( )
● create( )
● delete( )
● update( )
● count( )

Field Lookups
● exact
● icontains
● contains
● in
● gte
● lte
● gt

Migrations And Managers
Migrations - A way of propagating changes you make to your
models.
Managers - A manager is the interface through which DB
query operations are provided to django model.

The view layer
❖ URL
❖ Error Handling (Built In Views)
❖ Class Based Views

How Django processes a request?
● ROOT_URLCONF
● urlpatterns
● Runs in order and stops when matches.
● Once matches, django imports and calls the given view.
● If no path matches, exception is raised during any point in
the process.

Error Handling
❖ handler400 ( Bad request)
❖ handler 403 ( Forbidden)
❖ handler 404 ( Page not
Found)
❖ handler 500 (Server Error)

Class Based
Views
● Seperate get, post method
instead of conditional branching
● Multiple Inheritance(Using
Mixins)
● Decorating class-based Views

The template layer
❖ Language overview
❖ Built-in tags and filters (block, comment, lower, firstof)
❖ Custom tags and filters

Django Request
Response Cycle and
The Middlewares

WSGI
Connecting
Web Server
and
Web Framework
A gatekeeper between your web
server and Django Application.

Between the server and the application lie the
middlewares. You can think of middlewares as
a series of bidirectional filters.
Middlewares

The Big Picture — Data Flow

Middlewares ❏ process_request
❏ process_view
❏ process_exception
❏ process_response
Middleware Methods

Django

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