Django2.1 Tutotrial Lab

Hosting:

• Read The Docs, Django2.1 Tutotrial Lab

The main purpose of this project is to practice Django 2.1 Getting started effectively.

Like Yoga’s daily practice, I need a routine to awaken my body and mind. Same as programming, I need lab to maintain skills to invoke idea.

Simple is Power

Repeat practice and find out your weakness.

You have your right to be an individual thinker.

Terminal Prompt

Before activate virtual environment:

export PS1='$ '

After activate virtual environment:

export PS1='(venv)$ '

To determine which python:

which python

Table of Contents

Writing your first Django app, part 1

• Django Getting started, part 1
• Read The Docs, part 1

1-1. Virtual Envrionment

Lab:

$ python3.6 -v venv venv
$ source venv/bin/activate
(venv)$ pip install django
(venv)$ pip freeze

Note

$ To check installed packages.

1-2. Start Project

Lab:

(venv)$ django-admin startproject mysite
(venv)$ cd mysite
(venv)$ python manage.py runserver

Note

To see a rocket!

1-3. Start App

Lab:

(venv)$ python manage.py startapp polls
*** edit mysite/urls.py
*** add polls/urls.py
*** edit polls/views.py
*** add go.py
(venv)$ . go

• mysite/urls.py:

  from django.contrib import admin
  from django.urls import path,include
  
  urlpatterns = [
      path('admin/', admin.site.urls),
      path('polls/', include('polls.urls')),
  ]
  

• polls/urls.py:

  from django.urls import path
  from . import views
  
  urlpatterns = [
    path('', views.index, name='index'),
  ]
  

• polls/views.py:

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

• go:

  python manage.py runserver
  

Note

To ensure http://127.0.0.1:8000/polls/ is working.

Warning

Be aware http://127.0.0.1:8000 is damaged!

Writing your first Django app, part 2

• Django Getting started, part 2
• Writing custom django-admin commands
• Read The Docs, part 2

2-1. Admin

Lab:

(venv)$ python manage.py migrate
(venv)$ python manage.py createsuperuser
(venv)$ . go

Note

http://127.0.0.1:8000/admin/, login to maintain user/group.

2-2. Model

Lab:

*** edit mysite/settings.py
*** edit poll/models.py
*** edit poll/admin.py
*** edit go
. go

• mysite/settings.py:

  INSTALLED_APPS = [
     'polls',
     'django.contrib.admin',
     ...
  

• 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')
      def __str__(self):
          return self.question_text
  
  class Choice(models.Model):
      question = models.ForeignKey(Question, on_delete=models.CASCADE)
      choice_text = models.CharField(max_length=200)
      votes = models.IntegerField(default=0)
      def __str__(self):
          return self.choice_text
  

• polls/admin.py:

  from django.contrib import admin
  from .models import Question,Choice
  admin.site.register(Question)
  admin.site.register(Choice)
  

• go.py:

  python manage.py makemigrations
  python manage.py migrate
  python manage.py runserver
  

Note

Able to maintain Question and Choice.

2-3. Command

Lab:

*** add polls/management/commands/initpolls.py
python manage.py
python manage.py initpolls
. go

• polls/management/commands/initpolls.py:

  from django.core.management.base import BaseCommand, CommandError
  from polls.models import Question,Choice
  from django.utils import timezone
  
  class Command(BaseCommand):
      help = 'Create sample questions and choices.'
  
      def add_arguments(self, parser):
          parser.add_argument('question_num',type=int)
  
      def handle(self, *args, **options):
          q = Question.objects.all()
          q.delete()
  
          cnt = 0
          question_num = options['question_num']
          while (cnt < question_num):
              cnt += 1
              if cnt > 12:
                  self.stdout.write(self.style.WARNING('Max number was set to 12'))
                  break
              q = Question(question_text="Question #"+str(cnt),pub_date=timezone.now())
              q.save()
              q.choice_set.create(choice_text='Choice A for Question #'+str(cnt),votes=0)
              q.choice_set.create(choice_text='Choice B for Question #'+str(cnt),votes=0)
              q.choice_set.create(choice_text='Choice C for Question #'+str(cnt),votes=0)
  
          q = Question.objects.all()
          c = Choice.objects.all()
  
          self.stdout.write(self.style.SUCCESS('Questions "%s"' % q))
          self.stdout.write(self.style.SUCCESS('Choices "%s"' % c))
  

Writing your first Django app, part 3

References:

• Django Getting started, part 3
• Django Grils Tutorial, STATIC_ROOT
• Django , Django import / export

Hosting:

• Read The Docs, part 3

3-1. Polls Index

Lab:

*** edit polls/views.py
*** add polls/templates/polls/index.html

• polls/views.py:

  from django.shortcuts import render
  from .models import Question
  
  def index(request):
      latest_question_list = Question.objects.order_by('-pub_date')[:5]
      context = {'latest_question_list': latest_question_list}
      return render(request, 'polls/index.html', context)
  

• polls/templates/polls/index.html:

  {% if latest_question_list %}
    <ul>
    {% for question in latest_question_list %}
      <li><a href="/polls/{{ question.id }}/">{{ question.question_text }}</a></li>
    {% endfor %}
    </ul>
  {% else %}
    <p>No polls are available.</p>
  {% endif %}
  

Note

Show questions on our polls page.

3-2. Polls Detail

Lab:

*** edit polls/urls.py
*** edit polls/models.py
*** edit polls/views.py
*** edit polls/templates/polls/index.html
*** add polls/templates/polls/detail.html
. go

• polls/urls.py:

  from django.urls import path
  from . import views
  app_name = 'polls'
  
  urlpatterns = [
    path('', views.index, name='index'),
    path('<int:question_id>/', views.detail, name='detail')
  ]
  

• 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')
      def __str__(self):
          return self.question_text
  
  class Choice(models.Model):
      question = models.ForeignKey(Question, on_delete=models.CASCADE)
      choice_text = models.CharField(max_length=200)
      votes = models.IntegerField(default=0)
      def __str__(self):
          return self.question.question_text+" "+self.choice_text
  

• polls/views.py:

  from django.shortcuts import render,get_object_or_404
  from .models import Question
  
  def index(request):
      latest_question_list = Question.objects.order_by('-pub_date')[:5]
      context = {'latest_question_list': latest_question_list}
      return render(request, 'polls/index.html', context)
  
  def detail(request, question_id):
      question = get_object_or_404(Question, pk=question_id)
      return render(request, 'polls/detail.html', {'question': question})
  

• polls/templates/polls/index.html:

  {% if latest_question_list %}
    <ul>
    {% for question in latest_question_list %}
      <li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>
    {% endfor %}
    </ul>
  {% else %}
    <p>No polls are available.</p>
  {% endif %}
  

• polls/templates/polls/detail.html:

  <h1>{{ question.question_text }}</h1>
  <ul>
  {% for choice in question.choice_set.all %}
      <li>{{ choice.choice_text }}</li>
  {% endfor %}
  </ul>
  

3-3. Django import / export

Lab:

pip install django-import-export
pip freeze
*** edit mysite/setting.py
*** edit polls/admin.py
. go

• mysite/setting.py:

  INSTALLED_APPS = (
    'import_export',
    'polls',
    ...
  
  ...
  STATIC_URL = '/static/'
  # https://tutorial.djangogirls.org/en/django_start_project/
  STATIC_ROOT = os.path.join(BASE_DIR, 'static')
  

• polls/admin.py:

  from django.contrib import admin
  
  from import_export import resources
  from import_export.admin import ImportExportModelAdmin
  
  from .models import Question,Choice
  
  
  class QuestionResource(resources.ModelResource):
      class Meta:
          model = Question
  
  class QuestionAdmin(ImportExportModelAdmin):
      resource_class = QuestionResource
  
  admin.site.register(Question,QuestionAdmin)
  
  class ChoiceResource(resources.ModelResource):
      class Meta:
          model = Choice
  
  class ChoiceAdmin(ImportExportModelAdmin):
      resource_class = ChoiceResource
  
  admin.site.register(Choice,ChoiceAdmin)
  

Writing your first Django app, part 4

• Django Getting started, part 4
• Read The Docs, part 4

4-1. Forms

Lab:

*** edit polls/urls.py
*** edit polls/views.py
*** edit polls/templates/polls/detail.html
*** add polls/templates/polls/vote.html
*** add polls/templates/polls/result.html
. go

• polls/urls.py:

  from django.urls import path
  from . import views
  app_name = 'polls'
  
  urlpatterns = [
    path('', views.index, name='index'),
    path('<int:question_id>/', views.detail, name='detail'),
    path('<int:question_id>/vote/', views.vote, name='vote'),
    path('<int:question_id>/results/', views.results, name='results'),
  ]
  

• polls/views.py:

  from django.http import HttpResponse, HttpResponseRedirect
  from django.shortcuts import get_object_or_404, render
  from django.urls import reverse
  
  from .models import Choice, Question
  
  def index(request):
      latest_question_list = Question.objects.order_by('-pub_date')[:5]
      context = {'latest_question_list': latest_question_list}
      return render(request, 'polls/index.html', context)
  
  def detail(request, question_id):
      question = get_object_or_404(Question, pk=question_id)
      return render(request, 'polls/detail.html', {'question': question})
  
  def vote(request, question_id):
      question = get_object_or_404(Question, pk=question_id)
      try:
          selected_choice = question.choice_set.get(pk=request.POST['choice'])
      except (KeyError, Choice.DoesNotExist):
          # Redisplay the question voting form.
          return render(request, 'polls/detail.html', {
              'question': question,
              'error_message': "You didn't select a choice.",
          })
      else:
          selected_choice.votes += 1
          selected_choice.save()
          # Always return an HttpResponseRedirect after successfully dealing
          # with POST data. This prevents data from being posted twice if a
          # user hits the Back button.
          return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))
  
  def results(request, question_id):
      question = get_object_or_404(Question, pk=question_id)
      return render(request, 'polls/results.html', {'question': question})
  

• polls/templates/polls/detail.html:

  <h1>{{ question.question_text }}</h1>
  
  {% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}
  
  <form action="{% url 'polls:vote' question.id %}" method="post">
  {% csrf_token %}
  {% for choice in question.choice_set.all %}
      <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}">
      <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br>
  {% endfor %}
  <input type="submit" value="Vote">
  </form>
  

• polls/templates/polls/results.html:

  <h1>{{ question.question_text }}</h1>
  
  <ul>
  {% for choice in question.choice_set.all %}
      <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
  {% endfor %}
  </ul>
  
  <a href="{% url 'polls:detail' question.id %}">Vote again?</a>
  

Note

Able to vote

Writing your first Django app, part 5

• Django Getting started, part 5
• Read The Docs, part 5

5-1. Test

Lab:

*** edit mysite/urls.py
*** edit polls/tests.py
*** add polls/templates/index.html
(venv)$ python manage.py test

• polls/urls.py:

  from django.contrib import admin
  from django.urls import path,include
  from django.views.generic import TemplateView
  
  urlpatterns = [
      path('admin/', admin.site.urls),
      path('polls/', include('polls.urls')),
      path('', TemplateView.as_view(template_name="index.html"),name='index'),
  ]
  

• polls/tests.py:

  from django.test import TestCase
  from django.utils import timezone
  from django.urls import reverse
  import datetime
  
  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)
  
      def test_hello_world(self):
          response = self.client.get(reverse('index'))
          self.assertEqual(response.status_code, 200)
          self.assertContains(response, "Hello World!")
  

• polls/templates/index.html:

  Hello World!
  

Note

Fix / with ‘Hello World!’ using CBV.

Writing your first Django app, part 6

• Django Getting started, part 6
• Django Girls Tutorials, Template extending
• Boostrap v4.2, Starter template
• Read The Docs, part 6

6-1. Template Extending

Lab:

*** edit polls/static/polls/style.css
*** add polls/templates/base.html
*** edit polls/templates/index.html
*** edit polls/templates/detail.html
*** edit polls/templates/results.html
(venv)$ python manage.py test

• polls/static/polls/style.css:

  body{
    margin-top: 12px;
  }
  
  li a {
      color: black;
  }
  

• polls/templates/base.html:

  {% load static %}
  <!doctype html>
  <html lang="en">
    <head>
      <!-- Required meta tags -->
      <meta charset="utf-8">
      <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
  
      <!-- Bootstrap CSS -->
      <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css" integrity="sha384-GJzZqFGwb1QTTN6wy59ffF1BuGJpLSa9DkKMp0DgiMDm4iYMj70gZWKYbI706tWS" crossorigin="anonymous">
      <link rel="stylesheet" type="text/css" href="{% static 'polls/style.css' %}">
      <title>Lab</title>
    </head>
    <body>
      <div class="container">
        <h1><a href='/polls/'>Django2.1 Tutotrial Lab</a></h1>
            <div class="row">
              <div class="col-md-8">
              {% block content %}
              {% endblock %}
              </div>
          </div>
      </div>
      <!-- Optional JavaScript -->
      <!-- jQuery first, then Popper.js, then Bootstrap JS -->
      <script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
      <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.6/umd/popper.min.js" integrity="sha384-wHAiFfRlMFy6i5SRaxvfOCifBUQy1xHdJ/yoi7FRNXMRBu5WHdZYu1hA6ZOblgut" crossorigin="anonymous"></script>
      <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js" integrity="sha384-B0UglyR+jN6CkvvICOB2joaf5I4l3gm9GU6Hc1og6Ls7i6U/mkkaduKaBhlAXv9k" crossorigin="anonymous"></script>
    </body>
  </html>
  

• polls/templates/index.html:

  {% extends 'polls/base.html' %}
  {% block content %}
  
  {% if latest_question_list %}
    <h3><ul>
    {% for question in latest_question_list %}
      <li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>
    {% endfor %}
  </ul></h3>
  {% else %}
    <p>No polls are available.</p>
  {% endif %}
  {% endblock %}
  

• polls/templates/detail.html:

  {% extends 'polls/base.html' %}
  {% block content %}
  <h3>{{ question.question_text }}</h3>
  
  {% if error_message %}<p><strong>{{ error_message }}</strong></p>{% endif %}
  
  <form action="{% url 'polls:vote' question.id %}" method="post">
  {% csrf_token %}
  {% for choice in question.choice_set.all %}
      <input type="radio" name="choice" id="choice{{ forloop.counter }}" value="{{ choice.id }}">
      <label for="choice{{ forloop.counter }}">{{ choice.choice_text }}</label><br>
  {% endfor %}
  <input class='btn btn-success' type="submit" value="Vote">
  </form>
  {% endblock %}
  

• polls/templates/results.html:

  {% extends 'polls/base.html' %}
  {% block content %}
  <h2>{{ question.question_text }}</h2>
  
  <ul>
  {% for choice in question.choice_set.all %}
      <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
  {% endfor %}
  </ul>
  
  <a class='btn btn-success' href="{% url 'polls:detail' question.id %}">Vote again?</a>
  {% endblock %}
  

Warning

You might need to ‘Clear Browsing Data’ to let css working during development.

Want List

Hosting:

• Read The Docs, Want List

Why?

From Django tutorial, we learned

python manage.py startapp polls

Later on we still need to create urls.py for route. And, to be production ready, we also need to have templates/polls/base.html, as well as static/polls/style.css. Why not to provide a much ready templates for startapp?

Learn lower level python

Something we need to guess to assume first. Then to verify and to adjust.

My desired startapp

References:

• Django ref, django-admin and manage.py

python manage.py startapp

根據個人的開發經驗，urls.py, templates/{{app_name}}/base.html, 總是會用到的，為什麼不預設就有呢？

從文檔和代碼看目前做法

模版

What’s standard startapp doing?

111

create the folder

222

copy files

333

replace variable with app name

To understand Django

Prepare envrionment to study Django:

$ pwd
/Users/pinglingchen/ksndjs/django001/django
$ ls
django
$ cd django
$ git remote -v
origin      https://github.com/twoutlook/django.git (fetch)
origin      https://github.com/twoutlook/django.git (push)
$ cd ..
$ ls
django
$ python3.6 -m venv venv
$ . venv/bin/activate
(venv) $ pip freeze
(venv) $ pip install -e django
Obtaining file:///Users/pinglingchen/ksndjs/django001/django/django
Collecting pytz (from Django==2.2.dev20190102231945)
  Using cached https://files.pythonhosted.org/packages/f8/0e/2365ddc010afb3d79147f1dd544e5ee24bf4ece58ab99b16fbb465ce6dc0/pytz-2018.7-py2.py3-none-any.whl
Collecting sqlparse (from Django==2.2.dev20190102231945)
  Using cached https://files.pythonhosted.org/packages/65/85/20bdd72f4537cf2c4d5d005368d502b2f464ede22982e724a82c86268eda/sqlparse-0.2.4-py2.py3-none-any.whl
Installing collected packages: pytz, sqlparse, Django
  Running setup.py develop for Django
Successfully installed Django pytz-2018.7 sqlparse-0.2.4
You are using pip version 10.0.1, however version 18.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
(venv) $ pip freeze
-e git+https://github.com/twoutlook/django.git@b5fe97a34ea527d4254b58c2e828450e7c32157f#egg=Django
pytz==2018.7
sqlparse==0.2.4
You are using pip version 10.0.1, however version 18.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
(venv) $

python manage.py startapp having urls.py