¶ Create a Django application with a postgres database
Django DEV mode
¶ Postgres
Download and install Postgres
https://postgresapp.com/downloads.html
¶ Configure the server (optional)
By default postgres use the port 5432.
By default postgres use the current user.
¶ User
¶ Create user
Example with user = docuser
CREATE USER docuser WITH ENCRYPTED PASSWORD 'password';
¶ Update role
ALTER ROLE docuser SET client_encoding TO 'utf8';
ALTER ROLE docuser SET default_transaction_isolation TO 'read committed';
¶ List users
\du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------------------+-----------
Arnaud | Superuser, Create role, Create DB | {}
docuser | | {}
postgres | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
¶ DATABASE
¶ Create a database
Example with database = blog
CREATE DATABASE blog;
¶ List Databases
\l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
Arnaud | Arnaud | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
blog | Arnaud | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
(5 rows)
¶ Update Database privilege
GRANT ALL PRIVILEGES ON DATABASE blog TO docuser;
\l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access privileges
-----------+----------+----------+-------------+-------------+-----------------------
Arnaud | Arnaud | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
blog | Arnaud | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =Tc/Arnaud +
| | | | | Arnaud=CTc/Arnaud +
| | | | | docuser=CTc/Arnaud
postgres | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 |
template0 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
template1 | postgres | UTF8 | en_US.UTF-8 | en_US.UTF-8 | =c/postgres +
| | | | | postgres=CTc/postgres
(5 rows)
¶ Connect to database
\c blog
You are now connected to database "blog" as user "Arnaud".
¶ List tables
\dt
Did not find any relations.
¶ Django
¶ Install django
pip install Django
¶ Django project
¶ Create a project
Example with project = django-postgresql
django-admin startproject django-postgresql
¶ Setup database in django
- Edit
settings.py - (Default) settings for sqlite3:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.sqlite3',
'NAME': BASE_DIR / 'db.sqlite3',
}
}
- Update settings for postgres
Example with:
- name = blog
- user = docuser
- password = 123456
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql',
'NAME': 'blog',
'USER': 'docuser',
'PASSWORD': '123456',
'HOST': 'localhost',
'PORT': 5432,
}
}
¶ Migrate database
¶ Migrate
python manage.py migrate
Operations to perform:
Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
Applying contenttypes.0001_initial... OK
Applying auth.0001_initial... OK
Applying admin.0001_initial... OK
Applying admin.0002_logentry_remove_auto_add... OK
Applying admin.0003_logentry_add_action_flag_choices... OK
Applying contenttypes.0002_remove_content_type_name... OK
Applying auth.0002_alter_permission_name_max_length... OK
Applying auth.0003_alter_user_email_max_length... OK
Applying auth.0004_alter_user_username_opts... OK
Applying auth.0005_alter_user_last_login_null... OK
Applying auth.0006_require_contenttypes_0002... OK
Applying auth.0007_alter_validators_add_error_messages... OK
Applying auth.0008_alter_user_username_max_length... OK
Applying auth.0009_alter_user_last_name_max_length... OK
Applying auth.0010_alter_group_name_max_length... OK
Applying auth.0011_update_proxy_permissions... OK
Applying auth.0012_alter_user_first_name_max_length... OK
Applying sessions.0001_initial... OK
¶ List tables after migrate
\dt
List of relations
Schema | Name | Type | Owner
--------+----------------------------+-------+---------
public | auth_group | table | docuser
public | auth_group_permissions | table | docuser
public | auth_permission | table | docuser
public | auth_user | table | docuser
public | auth_user_groups | table | docuser
public | auth_user_user_permissions | table | docuser
public | django_admin_log | table | docuser
public | django_content_type | table | docuser
public | django_migrations | table | docuser
public | django_session | table | docuser
(10 rows)
¶ Django admin
¶ Create a super user for Django admin
Example with
superuser = admin
email = admin@halia.ca
password = password
python manage.py createsuperuser
Username (leave blank to use 'arnaud'): admin
Email address: admin@halia.ca
Password:
Password (again):
This password is too common.
Bypass password validation and create user anyway? [y/N]: y
Superuser created successfully.
¶ Run django server
python manage.py runserver
Watching for file changes with StatReloader
Performing system checks...
System check identified no issues (0 silenced).
February 13, 2022 - 05:07:48
Django version 3.1.7, using settings 'blog.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
¶ Acces to Django admin
Example with
url = http://127.0.0.1:8000/admin (default)
¶ (Optional) Rename url for Django admin
Case when you want to change the default admin url.
- Edit
blog/urls.py - Update
urlpatterns - Restart django server
Example with route = django-admin
urlpatterns = [
path('django-admin/', admin.site.urls),
]
¶ Django application
¶ Create a Django application
Example with app = posts
python manage.py startapp posts
¶ Add application in INSTALLED_APPS
- Edit
settings.py - Add
postsat the end ofINSTALLED_APPS
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'posts',
]
¶ Create a Model
- Edit
posts/models.py
from django.contrib.auth import get_user_model
from django.db import models
from django.template.defaultfilters import slugify
User = get_user_model()
class BlogPost(models.Model):
"""New BlogPost model."""
title = models.CharField(max_length=255, unique=True, verbose_name="Title")
slug = models.SlugField(max_length=255, unique=True, blank=True)
author = models.ForeignKey(User, on_delete=models.SET_NULL, null=True,
blank=True)
last_updated = models.DateTimeField(auto_now=True)
created_on = models.DateField(blank=True, null=True)
published = models.BooleanField(default=False, verbose_name="Published")
content = models.TextField(blank=True, verbose_name="Content")
class Meta:
"""
Override Meta class.
ordering: ordering on field created_on
verbose_name: Application name is Article
"""
ordering = ['-created_on']
verbose_name = 'Post'
def __str__(self):
"""Display title in Django admin."""
return self.title
def save(self, *args, **kwargs):
"""Create a slug with slugify based on title."""
if not self.slug:
self.slug = slugify(self.title)
super().save(*args, **kwargs)
@property
def author_or_default(self) -> str:
"""Get author or return unknown."""
return self.author.username if self.author else "unknown"
¶ Set DEFAULT_AUTO_FIELD or default_auto_field
Before Django 3.2, the primary key field that Django would add was of type 'django.db.models.AutoField'. Since Django 3.2 the default has been changed to 'django.db.models.BigAutoField'.
In order to get rid of the warning you need to set the DEFAULT_AUTO_FIELD in the settings to the field you prefer for primary keys. If you rather keep the Django 3.1 default you should set the auto-field value to 'django.db.models.AutoField'. This can also prevent some unwanted migrations in the future.
You can either set the value in your settings.py:
DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'
Or set it per app in the posts/apps.py file:
from django.apps import AppConfig
class PostsConfig(AppConfig):
default_auto_field = 'django.db.models.AutoField'
name = 'posts'
¶ Display new model in Django admin
- Edit
posts/admin - Create a new class
from django.contrib import admin
from posts.models import BlogPost
class BlogPostAdmin(admin.ModelAdmin):
"""BlogPostAdmin."""
list_display = ("title", "published", "created_on", "last_updated")
list_editable = ("published", )
admin.site.register(BlogPost, BlogPostAdmin)
¶ List model in Django admin
Remember that BlogPost has been renamed with
Post
verbose_name = 'Post'
Django add asat the end ofPost
¶ Templates
¶ Create core template
At the root of project
- create
templatesdirectory - create
core.htmlfile
¶ Update TEMPLATES in settings.py
- Edit
settings.py - Update
DIRSinTEMPLATES
TEMPLATES = [
{
'BACKEND': 'django.template.backends.django.DjangoTemplates',
'DIRS': [BASE_DIR / "templates"],
'APP_DIRS': True,
'OPTIONS': {
'context_processors': [
'django.template.context_processors.debug',
'django.template.context_processors.request',
'django.contrib.auth.context_processors.auth',
'django.contrib.messages.context_processors.messages',
],
},
},
]
¶ Edit core.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
{% block title %}
{% endblock %}
</head>
<body>
<section id="blog">
{% block content %}
{% endblock %}
</section>
</body>
</html>
¶ List all posts with CRUD (Read)
¶ Create view posts/views.py to list all posts
- Edit
posts/views.py - New class ListBlogPosts
from django.shortcuts import render
from django.views.generic import ListView
from posts.models import BlogPost
class ListBlogPosts(ListView):
"""ListBlogPosts."""
model = BlogPost
context_object_name = "posts"
¶ Create urls posts/urls.py to list all posts
- Create
posts/urls.pyfile - New path
from django.urls import path
from posts.views import ListBlogPosts
app_name = "posts"
urlpatterns = [
path('', ListBlogPosts.as_view(), name="home"),
]
¶ Update blog/settings.py by including posts.urls
- Edit
blog/urls.py - Add
path('blog/', include('posts.urls'))
urlpatterns = [
path('admin/', admin.site.urls),
path('blog/', include('posts.urls'))
]
¶ Create a template to list all posts
- Create
posts/templates/postsdirectory - Create
blogpost_list.htmlfile
{% extends 'core.html' %}
{% block title %}
<title>Home blog</title>
{% endblock %}
{% block content %}
<h1>Test blog</h1>
{% for post in posts %}
<article>
<h2>{{ post.title }}</h2>
<h5>published by <i>{{ post.author_or_default }}</i> on {{ post.created_on|date:'j F Y' }}</h5>
<p>{{ post.content|safe|truncatewords:50 }}</p>
</article>
{% endfor %}
{% endblock %}
¶ Use case #1: List posts based on user (writter) or reader
If a user registered on the website is authenticated then he is able to see all post, publiched and not published.
All other users will only see published posts.
- Update ListBlogPosts with get_queryset
- filter on published = True
class ListBlogPosts(ListView):
"""ListBlogPosts."""
model = BlogPost
context_object_name = "posts"
def get_queryset(self):
queryset = super().get_queryset()
if self.request.user.is_authenticated:
return queryset
return queryset.filter(published=True)
¶ Create a post with CRUD (Create)
¶ Edit view posts/views.py to create a post
- Edit
posts/views.py - Use of CreateView
class CreateBlogPost(CreateView):
"""CreateBlogPost."""
model = BlogPost
template_name = "posts/blogpost_create.html"
fields = ["title", "content"]
¶ Edit urls posts/urls.py to create a post
- Edit
posts/urls.pyfile - New path to create a post
from django.urls import path
from posts.views import ListBlogPosts, CreateBlogPost
app_name = "posts"
urlpatterns = [
path('', ListBlogPosts.as_view(), name="home"),
path('create/', CreateBlogPost.as_view(), name="create-post"),
]
¶ Create a template to create a post
- Use
posts/templates/postsdirectory - Create
blogpost_create.htmlfile
{% extends 'core.html' %}
{% block title %}
<title>Create a post</title>
{% endblock %}
{% block content %}
<h1>Create a post</h1>
<form method="POST">
{% csrf_token %}
{{ form }}
<input type="submit" value="Create">
</form>
{% endblock %}
¶ Define url redirection
- Edit model
posts.models.py - Add method to BlogPost
class BlogPost(models.Model):
"""New BlogPost model."""
...
@staticmethod
def get_absolute_url() -> Optional[str]:
"""
Get the absolute url for redirection.
see: posts.urls.py
app_name:name => posts:home
"""
return reverse("posts:home")
¶ Update a post with CRUD (Update)
url: http://127.0.0.1:8000/blog/update/<post.slug>
¶ Edit view posts/views.py to update a post
- Edit
posts/views.py - Use of UpdateView
class UpdateBlogPost(UpdateView):
"""UpdateBlogPost."""
model = BlogPost
template_name = "posts/blogpost_update.html"
fields = ["title", "content", "published"]
¶ Edit urls posts/urls.py to update a post
- Edit
posts/urls.pyfile - New path to update a post
from django.urls import path
from posts.views import ListBlogPosts, CreateBlogPost, UpdateBlogPost
app_name = "posts"
urlpatterns = [
path('', ListBlogPosts.as_view(), name="home"),
path('create/', CreateBlogPost.as_view(), name="create-post"),
path('update/<str:slug>/', UpdateBlogPost.as_view(), name="update-post"),
]
¶ Create a template to update a post
- Use
posts/templates/postsdirectory - Create
blogpost_update.htmlfile
{% extends 'core.html' %}
{% block title %}
<title>Update a post</title>
{% endblock %}
{% block content %}
<h1>Update a post</h1>
<form method="POST">
{% csrf_token %}
{{ form }}
<input type="submit" value="Update">
</form>
{% endblock %}
¶ Show a post with CRUD (Read)
url: http://127.0.0.1:8000/blog/<post.slug>
¶ Edit view posts/views.py to show a post
- Edit
posts/views.py - Use of DetailView
class ShowBlogPost(DetailView):
"""ShowBlogPost."""
model = BlogPost
context_object_name = "post"
template_name = "posts/blogpost_show.html"
¶ Edit urls posts/urls.py to show a post
- Edit
posts/urls.pyfile - New path to show a post
from django.urls import path
from posts.views import ListBlogPosts, CreateBlogPost, UpdateBlogPost, \
ShowBlogPost
app_name = "posts"
urlpatterns = [
path('', ListBlogPosts.as_view(), name="home"),
path('create/', CreateBlogPost.as_view(), name="create-post"),
path('update/<str:slug>/', UpdateBlogPost.as_view(), name="update-post"),
path('<str:slug>/', ShowBlogPost.as_view(), name="show-post"),
]
¶ Create a template to show a post
- Use
posts/templates/postsdirectory - Create
blogpost_show.htmlfile
{% extends 'core.html' %}
{% block title %}
<title>{{ post.title }} </title>
{% endblock %}
{% block content %}
<article>
<h1>{{ post.title }}</h1>
<h5>published by <i>{{ post.author_or_default }}</i> on {{ post.created_on|date:'j F Y' }}</h5>
<br>
<div>{{ post.content|linebreaks|safe }}</div>
</article>
{% endblock %}
¶ Delete a post with CRUD (Delete)
url: http://127.0.0.1:8000/blog/delete/<post.slug>
¶ Edit view posts/views.py to delete a post
- Edit
posts/views.py - Use of DeleteView
class DeleteBlogPost(DeleteView):
"""ShowBlogPost."""
model = BlogPost
context_object_name = "post"
template_name = "posts/blogpost_delete.html"
success_url = reverse_lazy("posts:home")
¶ Edit urls posts/urls.py to delete a post
- Edit
posts/urls.pyfile - New path to delete a post
from django.urls import path
from posts.views import ListBlogPosts, CreateBlogPost, UpdateBlogPost, \
ShowBlogPost, DeleteBlogPost
app_name = "posts"
urlpatterns = [
path('', ListBlogPosts.as_view(), name="home"),
path('create/', CreateBlogPost.as_view(), name="create-post"),
path('update/<str:slug>/', UpdateBlogPost.as_view(), name="update-post"),
path('delete/<str:slug>/', DeleteBlogPost.as_view(), name="delete-post"),
path('<str:slug>/', ShowBlogPost.as_view(), name="show-post"),
]
¶ Create a template to delete a post
- Use
posts/templates/postsdirectory - Create
blogpost_delete.htmlfile
{% extends 'core.html' %}
{% block title %}
<title>{{ post.title }}</title>
{% endblock %}
{% block content %}
<h1>Delete {{ post.title }}</h1>
<form method="POST">
{% csrf_token %}
<p>Are you sure you want to delete "{{ post.title }}"?</p>
<input type="submit" value="Yes, Delete">
</form>
{% endblock %}
¶ Restrict access for authenticated users
¶ Decorate class CreateBlogPost
- Allow authenticated users to access to create post
@method_decorator(login_required, name='dispatch')
class CreateBlogPost(CreateView):
"""CreateBlogPost."""
model = BlogPost
template_name = "posts/blogpost_create.html"
fields = ["title", "content"]
@method_decorator(login_required, name='dispatch')
class UpdateBlogPost(UpdateView):
"""UpdateBlogPost."""
model = BlogPost
template_name = "posts/blogpost_update.html"
fields = ["title", "content", "published"]
@method_decorator(login_required, name='dispatch')
class DeleteBlogPost(DeleteView):
"""ShowBlogPost."""
model = BlogPost
context_object_name = "post"
template_name = "posts/blogpost_delete.html"
success_url = reverse_lazy("posts:home")
¶ Navigation link
¶ Nav home and create post
- Edit
posts.templates.core.html - Add
<nav>section
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
{% block title %}
{% endblock %}
</head>
<body>
<nav>
<a href="{% url 'posts:home' %}">Home</a>
{% if request.user.is_authenticated %}
<a href="{% url 'posts:create-post' %}">Create a post</a>
{% endif %}
</nav>
<section id="blog">
{% block content %}
{% endblock %}
</section>
</body>
</html>
¶ Nav update post and delete post
- Edit
posts.templates.posts.blogpost_list.html
{% extends 'core.html' %}
{% block title %}
<title>Home blog</title>
{% endblock %}
{% block content %}
<h1>Test blog</h1>
{% for post in posts %}
<article>
<h2>{{ post.title }}</h2>
{% if request.user.is_authenticated %}
<div>
<a href="{% url 'posts:update-post' slug=post.slug %}">Update post</a>
<a href="{% url 'posts:delete-post' slug=post.slug %}">Delete post</a>
</div>
{% endif %}
<h5>published by <i>{{ post.author_or_default }}</i> on {{ post.created_on|date:'j F Y' }}</h5>
<p>{{ post.content|safe|truncatewords:50 }}</p>
<form action="{% url 'posts:show-post' slug=post.slug %}">
<button>Read post</button>
</form>
</article>
{% endfor %}
{% endblock %}