Django CheatSheet

Django_CheatSheet.txt

--------------------- SETUP -----------------------

1. Download Python 3.5
2. Update Path variables on Windows Path.
3. Install Cmder and run as Admin
4. Install Pycharm
5. $easy_install django
6. $easy_install virtualenv
7. django-admin startproject Santosh // Santosh is project name
8. Never edit manage.py, NEVER!
9. Setup USER and MASTER env variable PYTHONPATH "c:\users\horopter\appdata\local\programs\python\python35-32\lib\site-packages\django-1.10.3-py3.5.egg"
10. $easy_install virtualenv
11. cd in the folder Santosh having manage.py and $python manage.py runserver to launch at localhost:8000 [just like laravel]
12. $python manage.py migrate // if asked initially, else skip.
13. $python manage.py startapp music

----------------------- URLS MANAGEMENT --------------------

1. In Santosh\urls.py 
from django.conf.urls import url,include
from django.contrib import admin

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^music/', include('music.urls')),
]

2. In music\urls.py
from django.conf.urls import url
from . import views

urlpatterns = [
    url(r'^$', views.index, name='index'),
]

3. In views.py
from django.shortcuts import render
from django.http import HttpResponse

# Create your views here.

def index(request):
    return HttpResponse('<h1>This is a http response.</h1>')
	
-------------------- DATABASE SETUP -------------------

1. Santosh\settings.py
Check for DATABASES section for changing Database Engine

-------------------- MODEL CREATION ---------------------

1. music\models.py
from __future__ import unicode_literals

from django.db import models

# Create your models here.

class Album(models.Model):
    artist = models.CharField(max_length=256)
    album_title = models.CharField(max_length=512)
    genre = models.CharField(max_length=100)
    album_logo = models.CharField(max_length=100)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

class Song(model.Model):
    album = models.ForeignKey(Album,on_delete=models.CASCADE)
    file_type = models.CharField(max_length=10)
    song_title = models.CharField(max_length=256)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

2. Add 'music.apps.MusicConfig', to InstalledApps sections in Santosh\settings.py

3. python manage.py makemigrations music

4. python manage.py migrate

----------------------- DATABASE API -----------------

1. Album.objects.all() gives an array of all objects like select query.
2. We can override the behavior by __str__(self) method.
3. Album.objects.filter(id=2), Album.objects.filter(artist__startswith='Taylor')
4. a = Album(<key>=<value>,...) and a.save() to insert

---------------------- ADMIN CONTROL ------------------

$python manage.py createsuperuser

In admin.py of music, add
 
from models import Album
admin.site.register(Album)

------------------------- ADDING ANOTHER VIEW -----------------
 
 Simple GET request
 
 1. url(r'^(?P<id>[0-9]+)/$', views.detail , name='detail') in music\urls.py
 2. def detail(request,id):
    return HttpResponse('<h2>Details for album id :'+id+' </h2>') in music\views.py
	
-------------------------- RETRIEVING DATA FROM DB ---------------
1. In  views.py
from django.shortcuts import render
from django.http import HttpResponse
from models import Album

# Create your views here.

def index(request):
    all_albums = Album.objects.all()
    html = ''
    for album in all_albums:
        url = '/music/' + str(album.id) + '/'
        html += '<a href="'+url+'">'+album.album_title+'</a><br/>'
    return HttpResponse(html)

def detail(request,id):
    return HttpResponse('<h2>Details for album id :'+id+' </h2>')
	
----------------------------- TEMPLATES INTRODUCTION ----------------

1. In views.py
from django.shortcuts import render
from django.http import HttpResponse
from models import Album
from django.template import loader

# Create your views here.

def index(request):
    all_albums = Album.objects.all()
    context = {
        'all_albums' : all_albums,
    }
    template = loader.get_template('music/index.html')
    return HttpResponse(template.render(context,request))
    #or return render(request,'music/index.html',context) instead of above two lines

def detail(request,id):
    return HttpResponse('<h2>Details for album id :'+id+' </h2>')
	
2. Code changes are below : add a folder templates in music folder. Within templates add music folder and within that, add index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    {%if all_albums%}
    {%for album in all_albums%}
    <ul>
        <li>
            <a href="/music/{{album.id}}">{{album.title}}</a>
        </li>
    </ul>
    {%endfor%}
    {%else%}
    <h1>You don't have any albums</h1>
    {%endif%}
</body>
</html>

------------------------- RAISING A 404 ERROR -----------------
1. In views.py

from django.shortcuts import render
from django.http import HttpResponse,Http404
from models import Album
from django.template import loader

# Create your views here.

def index(request):
    all_albums = Album.objects.all()
    context = {
        'all_albums' : all_albums,
    }
    template = loader.get_template('music/index.html')
    return HttpResponse(template.render(context,request))
    #or return render(request,'music/index.html',context) instead of above two lines

def detail(request,id):
    try:
        album = Album.objects.get(pk=id)
    except Album.DoesNotExist:
        raise Http404("It doesn't exist")
    return render(request, "music/detail.html", {'album' : album})


****** To see standard 404 page, set DEBUG = false in settings.py