#Django

1. Django ORM

The Django web framework includes a default object-relational mapping layer (ORM) that can be used to interact with various relational databases such as SQLite, PostgreSQL, and MySQL. It allows us to add, delete, modify, and query objects.

An object-relational mapper provides an object-oriented layer between relational databases and object-oriented programming languages without having to write SQL queries.

Relationship

Django supports relational databases and allows us to establish relations between different models. There are three types of relational fields which Django supports: many-to-one, many-to-many and one-to-one.

Django Tools

• Simple ways to get Queries details
  • queryset.explain()
  • query_debugger.py

1. API

API stands for Application Programming Interface. It’s a software interface that allows two or more applications to interact with each other without any user intervention.

It offers products or services to communicate with other products and services without having to know how they’re implemented.

Protocols that can be used in APIs are TCP, SMTP, HTTP

REST API

REpresentational State Transfer API (Application Programming Interface)

Its an architectural style for providing standards between computer systems on the web, making it easier for systems to communicate with each other.

• It provides a set of principles/rules for building web services that used HTTP as a communication protocol.
• An API that follows REST standard are called as RESTful API
• GET, POST, PATCH, PUT and DELETE

Serialization

Serializers allow complex data such as querysets and model instances to be converted to native Python datatypes that can then be easily rendered into JSON, XML or other content types.

Serializers also provide deserialization, allowing parsed data to be converted back into complex types, after first validating the incoming data.

Request Object

REST framework introduces a Request object that extends the regular HttpRequest, and provides more flexible request parsing.

The core functionality of the Request object is the request.data attribute, which is similar to request.POST, but more useful for working with Web APIs.

• request.POST
  • Only handles form data.
  • Only works for 'POST' method.
• request.data
  • Handles arbitrary data.
  • Works for ‘POST’, ‘PUT’ and ‘PATCH’ methods.

Class-based Views

Keep our code DRY(Don’t repeat yourself).

One of the big wins of using class-based views is that it allows us to easily compose reusable bits of behaviour.

# Types
* APIview
* Mixins
* Generic

6.1 ViewSets

ViewSet classes are almost the same thing as View classes, except that they provide operations such as retrieve, or update, and not method handlers such as get or put.

In other word ViewSet class is simply a type of class-based View, that does not provide any method handlers such as .get() or .post(), and instead provides operations/actions such as .list() and .create().

ModelSerializer vs HyperlinkedModelSerializer

• ModelSerializer
  • By default, Relationship will show –> as primary keys
• HyperlinkedModelSerializer
  • By default, Relationship will show –> as url