francoiducat/django-tutorial

Django app tutorial which walks through creating a basic poll application

Django-tutorial

Django app tutorial which walks through creating a basic poll application

Set up default python version with oh-my-zsh

~ vi .zshrc
~ alias python=/usr/local/bin/python3

Install Django

~ python -m pip install Django

Check Django version

Option 1

~ python
>>> import django
>>> print(django.get_version())
>>> 3.2.5

Option 2

~ python -m django --version
> 3.2.5

Create Django project

django-admin startproject app

Run Django Development Server

~ python manage.py runserver 8000

Create Postgresql Database

CREATE DATABASE polls
    WITH
    OWNER = polls
    ENCODING = 'UTF8';

Setup Database ENGINE

In settings.py edit this bloc :

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'HOST': 'localhost',
        'NAME': 'polls',
    }
}

Run migration to create the tables

➜  django-project git:(main) ✗ 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

Create models

Add this to polls/models.py

from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)

Add the polls app to the project

In project/settings.py edit this bloc:

INSTALLED_APPS = [
    'polls.apps.PollsConfig',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

Include the polls app

Run this command :

➜  django-project git:(main) ✗ python manage.py makemigrations polls
Migrations for 'polls':
  polls/migrations/0001_initial.py
    - Create model Question
    - Create model Choice

Check Sqlmigrate command

The sqlmigrate command takes migration names and returns their SQL:

➜  django-project git:(main) ✗ python manage.py sqlmigrate polls 0002
BEGIN;
--
-- Alter field choice_text on choice
--
ALTER TABLE "polls_choice" ALTER COLUMN "choice_text" TYPE varchar(250);
--
-- Alter field question_text on question
--
ALTER TABLE "polls_question" ALTER COLUMN "question_text" TYPE varchar(250);
COMMIT;

Optionally, perform system check:

➜  django-project git:(main) ✗ python manage.py check;
System check identified no issues (0 silenced).

Create model tables

Run migrate again to create model tables in database:

➜  django-project git:(main) ✗ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, polls, sessions
Running migrations:
  Applying polls.0001_initial... OK
  Applying polls.0002_auto_20210713_1558... OK

Sum up :

1. Change your models (in models.py).
2. Run python manage.py makemigrations to create migrations for those changes
3. Run python manage.py migrate to apply those changes to the database.

Play with python api

See https://docs.djangoproject.com/en/3.2/intro/tutorial02/

python manage.py shell

Django Admin

Create admin User

python manage.py createsuperuser

Add first views

Edit polls/views.py

from django.http import HttpResponse

def index(request):
    return HttpResponse("Hello, world. You're at the polls index.")

def detail(request, question_id):
    return HttpResponse("You're looking at question %s." % question_id)

def results(request, question_id):
    response = "You're looking at the results of question %s."
    return HttpResponse(response % question_id)

def vote(request, question_id):
    return HttpResponse("You're voting on question %s." % question_id)

Wire first views to urls

Edit polls/urls.py

from django.urls import path

from . import views

urlpatterns = [
    # ex: /polls/
    path('', views.index, name='index'),
    # ex: /polls/5/
    path('<int:question_id>/', views.detail, name='detail'),
    # ex: /polls/5/results/
    path('<int:question_id>/results/', views.results, name='results'),
    # ex: /polls/5/vote/
    path('<int:question_id>/vote/', views.vote, name='vote'),
]

Unit Test

Write

Create tests.py file in the polls folder:

import datetime

from django.test import TestCase
from django.utils import timezone

from .models import Question


class QuestionModelTests(TestCase):

    def test_was_published_recently_with_future_question(self):
        """
        was_published_recently() returns False for questions whose pub_date
        is in the future.
        """
        time = timezone.now() + datetime.timedelta(days=30)
        future_question = Question(pub_date=time)
        self.assertIs(future_question.was_published_recently(), False)

Run

python manage.py test polls