Back-end-NOTE.md

Development Note

12/18/2017

Development Tools

• Visual Studio Code
• Yarn
• Python 3.6
• Pip
• Pipenv
• Postgres
• Django 1.11

Django

• Overview
• Framework
• Not a programming language
• Very fast for developers
• Secure
• Handy
• Used by (Instagram, Pinterest, Spotify, NASA)

Framework vs Library

• A library is a tool
• A framework is a way of life
• A library is just functions you can call
• A framework calls your code
• You call the library
• The framework calls you

Django comes with

• ORM (talk to the database)
• Admin Panel
• User Authentication
• URL Dispatcher
• Template Engine

Virtual Environments

• Imagine a bubble
• What happens in the bubble stays in the bubble
• You can have as many bubbles as you want

Why Virtual Environment?

• Because global dependencies are not okay
• Many times you will need different dependency versions

How?

• Virtualenv
• Virtualenvwrapper
• Pipenv

Creating a Virtual Environment

pipenv --three 	        // create a bubble with python version 3
pipenv install django   // install django package in this bubble 
pipenv shell            // go into a bubble 
exit 	                // exit bubble  

Parts of Django

Settings, Urls, and Apps

Settings

• Change the default behavior of Django
• Install more modules
• Remove default ones
• Django will look at this file whenever it starts

Urls

• The Django project is gonna be open to the internet
• URLS are how you talk to the Django project and make him do things
• When Django matches an URL it will execute a view function.

Apps

• Apps are what the applications is made of
• Apps have a defined scope and they responsibilities are very precise
• A Django project can have as many apps as you want

Creating Django Project

• Production-ready-size
• Cookiecutter Django

pipenv install cookiecutter
pipenv shell
cookiecutter https://github.com/pydanny/cookiecutter-django

Installing the requirements

pipenv --three
pipenv shell
pipenv install -r requirements/local.tx

12/21/2017

Production Settings and Local Settings

• Production Settings: Settings that are gonna be loaded on the live server

• Local Settings: Settings that are gonna be loaded on the local server

Creating database with Postgres

CREATE DATABASE databasename;

Migrating

• A migration is a process to change the shape of the database models
• When we add, remove or update DB columns we have to migrate

python manage.py makemigrations
python manage.py migrate

• Django Model Field
• Django Model Documentation

Abstract base classes

• Abstract base classes are useful when you want to put some common information into a number of other models.

Model Relationships

• Django _set Automatically groups all the related objects into a property To call the objects related to the owner all we have to do is call ‘modelName_set’

• Define many-to-many relationship

followers = models.ManyToManyField(‘self’)
following = models.ManyToManyField(‘self’)

RESTful API Designing guidelines

Django Rest Framework

pipenv install djangorestframework

• Serializer converts Python Object to JSON (and other way around)
• Bridge between Python and JavaScript

Django Rest Framework APIView

12/22/2017

Django URL Dispatcher

• Let Django know the requested urls

url(r'^images/', include('sodagram.images.urls', namespace='images')) 

Nested Relationships Serializers

• Instead of getting the foreign key, get Serializer for image

image = ImageSerializer()

Hidden Model Fields in Django

• Related Objects Reference
• What is related_name used for in Django?

The Request Object in Django

• Django uses request and response objects to pass state through the system.
• When a page is requested, Django creates an HttpRequest object that contains metadata about the request.
• Then Django loads the appropriate view, passing the HttpRequest as the first argument to the view function.
• Each view is responsible for returning an HttpResponse object.
• Mostly used attributes (POST, USER)
• Request and Response Objects
• Request Attributes set by Middleware (user)
• Django Middleware Documentation
• Understanding Django Middlewares

Making Queries

• Making Queries on Django
• QuerySet Reference

Capturing arguments on Django URL's

regex=r'(?P<image_id>[0-9]+)/like/'

• Testing Regular Expression

12/23/17

Limiting QuerySets

>>> Entry.objects.all()[:5]         // returns first five objects

Getting User Profile

• Fields to be shown when clicking profile
• username
• name
• bio
• website
• post count
• followers count
• following count
• images
• Define UserProfileImageSerializer in images.serializers

class UserProfileImageSerializer(serializers.ModelSerializer):

    class Meta:
        model = models.Image
        fields =(
            'id',
            'file',
            'comment_count',
            'like_count'
        )

• Import UserProfileImageSerializer from images.serializers to user.serializer

from sodagram.images import serializers as images_serializers

// and get images of this profile

images = images_serializers.UserProfileImageSerializer(many=True)

12/24/17

Hashtag

• django-taggit
• Django Taggit Documentation

pipenv install django-taggit
python manage.py migrate

• Django Taggit Rest Serializer

pipenv install django-taggit-serializer

12/28/17

Change password

• Check password documentation
• check_password(raw_password)
• set_password(raw_password)

JWT Token (JSON Web Token)

• Introduction to Json Web Tokens
• REST framework JWT Auth
• pipenv install djangorestframework-jwt
• Protection for our API

// include into base.py
REST_FRAMEWORK = {
    'DEFAULT_PERMISSION_CLASSES': (
        'rest_framework.permissions.IsAuthenticated',
    ),
    'DEFAULT_AUTHENTICATION_CLASSES': (
        'rest_framework_jwt.authentication.JSONWebTokenAuthentication',
        'rest_framework.authentication.SessionAuthentication',
        'rest_framework.authentication.BasicAuthentication',
    ),
}

// include into urls.py
from rest_framework_jwt.views import obtain_jwt_token
#...

urlpatterns = [
    '',
    # ...

    url(r'^api-token-auth/', obtain_jwt_token),
]

Postman

• API call using JSON Web Token

12/29/17

Login : Signup

• Django Rest Auth on Github
• Django Rest Auth Documentation

Login with Facebook

• Django-allauth