django - Create Project
Creating a project
cd into a director where you like to store your project/codes and run the command below
django-admin startproject mysite
Run server
Run the command below to start the dev server
python manage.py runserver
Start app
In Python Django app means different section of your application. If you have a shop then it’s shop app. If you have a forum, then it’s a forum app. To start an app, call the command below and it will create a folder name called music
python manage.py startapp music
Create a home page view
Under /music/views.py
from django.http import HttpResponse
def index(request):
return HttpResponse('<h1>hello world</h1>')
Under /mysite/settings.py
INSTALLED_APPS = [
...
'music.apps.MusicConfig'
]
Under /mysite/urls.py
from django.conf.urls import include, url
urlpatterns = [
url(r'^music/', include('music.urls'))
]
Create model/database
from django.db import models
# pk will be created
class Album(models.Model):
artist = models.CharField(max_length=250)
album_title = models.CharField(max_length=250)
genre = models.CharField(max_length=250)
album_logo = models.CharField(max_length=1000)
# associate with any album. 'on_delete=models.CASCADE' is whenever album is deleted, song associate with it will be deleted as well
class Song(models.Model):
album = models.ForeignKey(Album, on_delete=models.CASCADE)
file_type = models.CharField(max_length=10)
song_title = models.CharField(max_length=250)
Activiting models
Once you have defined or updated the model. Run the command below to ensure it works with the DB correctly.
python manage.py makemigrations music
Sync the DB
Run the following command once you successfully made the migration. This will sync up the changes with the DB
python manage.py migrate
DJango shell
You can open up django interactive shell in your terminal from the command below. With this shell, you can write database commnads.
python manage.py shell
# once you are in the shell, you can add album object via the commands below
# retreive all album objects
Album.objects.all()
# import Album and Song
from music.models import Album, Song
# Add album
a = Album(artist="artist_1", album_title="title_1", genre="genre_1", album_logo="logo_1")
b = Album()
b.artist="artist_2"
b.album_title="title_2"
b.genre="genre_2"
b.album_logo="logo_2"
# Save the changes
a.save()
b.save()
Special representation of an instance
When you type in Album.objects.all() you’ll always see something like Query[objects]. This is not useful. To change that in your Album class add the following def
def __str__(self):
return self.album_title + ' - ' + self.artist
Filter
You can use filter method to filter through the albums
# return first album
Album.objects.filter(pk=1)
# return an album that has artist name starts with 'my'
# output: [<Album: Punk - Myth>]
Album.objects.filter(artist__startswith="my")
Admin interface
To create an admin, use the commands below
python manage.py createsuperuser
Once you filled up the info, go to your admin path. (e.g. 127.0.0.1/admin)
How to add music to the admin site
We want to able to make CRUD operation to the ablum
Under music/admin.py
from django.contrib import admin
from .models import Album
# Register your models here.
admin.site.register(Album)
Add view
We want to add another view after music url. Something like /music/80
In your music/urls.py add a detail view
urls(r'^(?P<album_id>[0-9]+)/$', views.detail, name='detail')
In your music/views.py
def detail(request, album_id):
return HttpResponse(f"<h2>Details for album id { album_id }</h2>")
Go to your http://127.0.0.1:8000/music/1/
Connecting to the database
from .models import Album
# Album.objects.all() will return all album objects
def index(request):
all_album = Album.objects.all()
Templates
Create a templates/music/index.html index file under music folder
In the views.py file
from django.http import HttpResponse
from django.shortcuts import render
from .models import Album
def index(request):
# get all albums from the DB
all_album = Album.objects.all()
# data context
context = { 'all_album': all_album }
# note that we don't need to pass in templates path as django already mapped behind the code
return render(request, 'music/index.html', context)
in the index.html file
<h3>You do not have any albums</h3>
Related Ojbects Set
This is faster better way to add related objects.
# fire up your django interactive shell
python manage.py shell
# import Album and Song
from music.models import Album, Song
# add songs to a specific album
album1 = Album.objects.get(pk=1)
# add song
album1.objects.create(song_title = 'song 1', file_type = 'mp3')
# to see all the songs we've added
album1.objects.all()