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Django

Course notes

Project Directory Structure

  1. To start a Django project, enter the command below in terminal:

    # django-admin startproject <project-name>
django-admin startproject project_name

  2. To create an app, cd to the project root (project_name/ in this case) and run:

    # python manage.py startapp <app-name>
python manage.py startapp app1

This creates the directory stucture below:

project_name/
├── project_name/    # website App: project-level configurations
│   ├── __init__.py
│   ├── settings.py  # Link Apps: INSTALLED_APPS
│   ├── urls.py      # Link apps' routes to main site 
│   └── wsgi.py
│ 
├── app1/
│   ├── migrations/
│   ├── templates/
│   │   └── app1/
│   │       ├── base.html
│   │       └── index.html
│   ├── static/
│   │       └── style.css
│   ├── __init__.py
│   ├── admin.py     # Customize administrator panel
│   ├── apps.py
│   ├── tests.py
│   ├── models.py    # app database definition
│   ├── urls.py      # app route
│   └── views.py     # app functions
│
├── manage.py
└── db.sqlite3

Common Commands

  • Start new Django project

    django-admin startproject <project-name>

  • Add new app

    python manage.py startapp <app-name>

  • Start server

    python manage.py runserver

  • Update database (after modifying <app-name>/models.py

    python manage.py makemigrations
python manage.py migrate

  • Django shell

    python manage.py shell
python manage.py shell < script.py

  • Create super user account

    python manage.py createsuperuser

settings.py

Every time a new app is created, remember to attach this new app to the project. To do this, find INSTALLED_APPS in project_name/settings.py and add the app to the list:

urls.py

Every app has one urls.py and project_name/ has one urls.py. project_name/urls.py defines the url relations of every app to the site. <app-name>/urls.py defines the relations between individual functions in <app-name>/views.py and url paths within an app.

For example, project_name/urls.py might look like the code below, where flights, users and admin (default Django app) are apps in the project:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('flights/', include('flights.urls')),
    path('users/', include('users.urls')),
    path('admin/', admin.site.urls),
]

flights/urls.py may look like the code below:

from django.urls import path
from . import views

urlpatterns = [
    path('', views.index, name='index'),
    path('<int:flight_id>', views.flight, name='flight'),
    path('<int:flight_id>/book', views.book, name='book')
]

The path functions essentially links the functions in views.py and url paths together in an app.

As an example, (after running the server locally) if you visit http://127.0.0.1:8000/flights/1/book, you will be on a page handled by the function book() defined in flights/views.py. This relationship is defined in path('<int:flight_id>/book', views.book, name='book'). The path right after the base url (http://127.0.0.1:8000/) is flights/ because it was defined in path('flights/', include('flights.urls')), in project_name/urls.py.

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