Djangoのチュートリアルを読んでいく！【その２ Django初心者】

はじめに

私はプログラミング歴１年の初心者です。
実務でWebサイトのコーディングを１年間行ってきました。
そろそろシステム開発もできるようになりたいということで
LaravelやReactをこれから勉強していこうと思っております。

今回の目的

Djangoでアプリを実際に作っていく流れを学ぼうと思います。
公式チュートリアルを読んでいきます。

目次

1. オーバービュー
2. 簡単なフォーム
3. テスト
4. モデル
5. アプリ公開

実践

オーバービュー

一覧ビューを実装

polls/views.py

# ビューを追加
def detail(request, question_id):
  return HttpResponse("You7re 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)

polls/urls.py

# Routingを追加
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'),
]

polls/views.py

# 動的なサイトを作ってみる(index()を変更)
from django.http import HttpResponse
from .models import Question

def index(request):
  latest_question_list = Question.objects.order_by('-pub_date')[:5]
  output = ', '.join([q.question_text for q in latest_question_list])
  return HttpResponse(output)

polls/templates/polls/index.html

# テンプレートフォルダを作成してビューを作成する(不完全HTML)
{% if latest_question_list %}
  <ul>
    {% for question in latest_question_list %}
      <li><a href="/polls/{{ quetsion.id }}/">{{ question.question_text }}</a></li>
    {% endfor %}
  </ul>
{% else %}
  <p>No polls are available.</p>
{% endif %}

polls/views.py

# indexビューを変更する
from django.template import loader

def index(request):
  latest_question_list = Question.objects.order_by('-pub_date')[:5]
  template = loader.get_template('polls/index.html')
  context = {
    'latest_question_list': latest_question_list,
  }
  return HttpResponse(template.render(context, request))

polls/view.py

# renderショートカットを使う(リファクタリング)
→こうすることでloaderやHttpResponseは必要なくなる
from django.shortcuts import render

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)

詳細ビューを実装

polls/views.py

# 詳細ビューを実装(404エラー画面)
from django.http import Http404

def detail(request, question_id):
  try:
    question = Question.objects.get(pk=question_id)
  except Question.DoesNotExist:
    raise Http404("Question does not exist")
  return render(request, 'polls/detail.html', {'question': question})

polls/templates/polls/detail.html

# とりあえず簡単に実装
{{ question }}

polls/views.py

# 404エラーショートカットを使う(リファクタリング)
from django.shortcuts import get_object_or_404, render

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/detail.html

# 詳細画面を実装する
<h1>{{ question.questionn_text }}</h1>
<ul>
  {% for choice in question.choice_set.all %}
    <li>{{ choice.choice_text }}</li>
  {% endfor %}
</ul>

ハードコードされているindexのURLを変更

polls/templates/polls/index.html

# 今までの書き方だと変更に強くない(テンプレートを直す必要あり)
<li><a href="/polls/{{ quetsion.id }}/">{{ question.question_text }}</a></li>

↓↓↓↓ 変更 ↓↓↓↓

# 変更に強くする(urlsモジュールを変更すればいい)
<li><a href="{% url 'detail' question_id %}">{{ question.question_text }}</a></li>

名前空間を使ってリファクタリング

polls/urls.py

# 名前空間を追加する
app_name = 'polls'

polls/templates/polls/index.html

# 名前空間のついた記述に変更する
<li><a href="{% url 'detail' question.id %}">{{ question.question_text }}</a></li>

↓↓↓↓ 以下のように変更 ↓↓↓↓
<li><a href="{% url 'polls:detail' question.id %}">{{ question.question_text }}</a></li>

作成保存機能

簡単なフォーム実装

polls/templates/polls/details.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/views.py

# urlsにはvoteを作成してあるので、vote()を実装
from django.http import HttpResponse, HttpResponseRedirect
from django.urls import reverse
from .models import Choice, 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):
    return render(request, 'polls/details.html', {
      'question': question,
      'error_message': "You didn't select a choice.",
    })
  else:
    selected_choice.votes += 1
    selected_choice.save()
    return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

結果画面を実装する

polls/views.py

# 結果画面ビューを編集する
from django.shortcuts import get_object_or_404, render

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/results.html

# 結果画面の実装
<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>

リファクタリング

polls/urls.py

# indexとdetailとresultのRoutingを変更する
urlpatterns = [
    # ex: /polls/
    path('', views.IndexView.as_view(), name='index'),
    # ex: /polls/5/
    path('<int:pk>/', views.DetailView.as_view(), name='detail'),
    # ex: /polls/5/results/
    path('<int:pk>/results/', views.ResultsView.as_view(), name='results'),
    # ex: /polls/5/vote/
    path('<int:question_id>/vote/', views.vote, name='vote'),
]

polls/views.py

# index,detail,resultsのビューをDjangoの汎用ビューに変更する
from django.http import HttpResponseRedirect
from django.urls import reverse
from django.views import generic

class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

    def get_queryset(self):
        """Return the last five published questions."""
        return Question.objects.order_by('-pub_date')[:5]


class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'


class ResultsView(generic.DetailView):
    model = Question
    template_name = 'polls/results.html'

テスト

プログラムが正しく動くことは先に確認しておくべき。
のちのち動かないことがわかったときに困る。

テストの無いコードは、デザインとして壊れている。

テスト駆動開発
→コードを書く前にテストを書く

テストコードは長くなってしまってもいいので
何をしているのかをわかりやすく

テスト作成

# shellでバグを確認する
$ python manage.py shell

>>> import datetime
>>> from django.utils import timezone
>>> from polls.models import Question
>>> future_question = Question(pub_date=timezone.now() + datetime.timedelta(days=30))
>>> future_question.was_published_recently()

polls/tests.py

# コメントも書きつつ、テストコードを書く
# テスト用のメソッドはtestから始まる
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_questions(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)

# テスト実行
$ python3 manage.py test polls

バグ修正

polls/models.py

# バグ修正をする
  def was_published_recently(self):
        return self.pub_date >= timezone.now() - datetime.timedelta(days=1)

↓↓↓↓ 変更する ↓↓↓↓

def was_published_recently(self):
        now = timezone.now()
        return now - datetime.timedelta(days=1) <= self.pub_date <= now

他のテストも追加する

polls/tests.py

# 他の包括的なテストも同じクラスに追加する
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_questions(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_was_published_recently_with_old_question(self):
    """
    was_published_recently() returns False for questions whose pub_date
    is older than 1 day.
    """
    time = timezone.now() - datetime.timedelta(days=1, seconds=1)
    old_question = Question(pub_date=time)
    self.assertIs(old_question.was_published_recently(), False)

  def test_was_published_recently_with_recent_question(self):
    """
    was_published_recently() returns True for questions whose pub_date
    is within the last day.
    """
    time = timezone.now() - datetime.timedelta(hours=23, minutes=59, seconds=59)
    recent_question = Question(pub_date=time)
    self.assertIs(recent_question.was_published_recently(), True)

ビューに関するテストも行う

ユーザーがブラウザを通して経験する動作をチェックする

# shellを使って確認する
$ python3 manage.py shell

>>> from django.test.utils import setup_test_environment
>>> setup_test_environment()
>>> from django.test import Client
>>> client = Client()
>>> response = client.get('/')
>>> response.status_code
>>> from django.urls import reverse
>>> response = client.get(reverse('polls:index'))
>>> response.status_code
>>> response.content
>>> response.context['latest_question_list']

polls/views.py

# get_querysetを修正する
class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

    def get_queryset(self):
        """Return the last five published questions."""
        return Question.objects.order_by('-pub_date')[:5]

↓↓↓↓ 以下のように変更する ↓↓↓↓
from django.utils import timezone

def get_queryset(self):
      """
      Return the last five published questions (not including those set to be
      published in the future).
      """
      return Question.objects.filter(
          pub_date__lte=timezone.now()
      ).order_by('-pub_date')[:5]

polls/tests.py

# 以下のビューのテストコードを追記する
from django.urls import reverse

def create_question(question_text, days):
  """
  Create a question with the given `question_text` and published the
  given number of `days` offset to now (negative for questions published
  in the past, positive for questions that have yet to be published).
  """
  time = timezone.now() + datetime.timedelta(days=days)
  return Question.objects.create(question_text=question_text, pub_date=time)


class QuestionIndexViewTests(TestCase):
  def test_no_questions(self):
      """
      If no questions exist, an appropriate message is displayed.
      """
      response = self.client.get(reverse('polls:index'))
      self.assertEqual(response.status_code, 200)
      self.assertContains(response, "No polls are available.")
      self.assertQuerysetEqual(response.context['latest_question_list'], [])

  def test_past_question(self):
      """
      Questions with a pub_date in the past are displayed on the
      index page.
      """
      question = create_question(question_text="Past question.", days=-30)
      response = self.client.get(reverse('polls:index'))
      self.assertQuerysetEqual(
          response.context['latest_question_list'],
          [question],
      )

  def test_future_question(self):
      """
      Questions with a pub_date in the future aren't displayed on
      the index page.
      """
      create_question(question_text="Future question.", days=30)
      response = self.client.get(reverse('polls:index'))
      self.assertContains(response, "No polls are available.")
      self.assertQuerysetEqual(response.context['latest_question_list'], [])

  def test_future_question_and_past_question(self):
      """
      Even if both past and future questions exist, only past questions
      are displayed.
      """
      question = create_question(question_text="Past question.", days=-30)
      create_question(question_text="Future question.", days=30)
      response = self.client.get(reverse('polls:index'))
      self.assertQuerysetEqual(
          response.context['latest_question_list'],
          [question],
      )

  def test_two_past_questions(self):
      """
      The questions index page may display multiple questions.
      """
      question1 = create_question(question_text="Past question 1.", days=-30)
      question2 = create_question(question_text="Past question 2.", days=-5)
      response = self.client.get(reverse('polls:index'))
      self.assertQuerysetEqual(
          response.context['latest_question_list'],
          [question2, question1],
      )

詳細ビューのテスト

polls/views.py

# 以下のget_queryset()を追加する
class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'

    def get_queryset(self):
      """
      Excludes any questions that aren't published yet.
      """
      return Question.objects.filter(pub_date__lte=timezone.now())

polls/test.py

# 以下のテストを追加する
class QuestionDetailViewTests(TestCase):
    def test_future_question(self):
        """
        The detail view of a question with a pub_date in the future
        returns a 404 not found.
        """
        future_question = create_question(question_text='Future question.', days=5)
        url = reverse('polls:detail', args=(future_question.id,))
        response = self.client.get(url)
        self.assertEqual(response.status_code, 404)

    def test_past_question(self):
        """
        The detail view of a question with a pub_date in the past
        displays the question's text.
        """
        past_question = create_question(question_text='Past Question.', days=-5)
        url = reverse('polls:detail', args=(past_question.id,))
        response = self.client.get(url)
        self.assertContains(response, past_question.question_text)

モデル

アプリ公開

さいごに

views.pyは
ビューコントローラみたいなものか？

チュートリアルを読むと
実際にPythonってこうやって使うのかというのがわかる

postメソッドというのは
サーバー側のデータの更新につながるものに使う