【初心者】Djangoで作ったToDoアプリを改良してみた

ブラウザ
  ↓ リクエスト（URLにアクセス）
config/urls.py     → どのアプリのurls.pyに渡すか振り分ける
  ↓
アプリのurls.py    → そのアプリの中でどのViewを呼ぶか振り分ける
  ↓
views.py           → 処理ロジック（必要に応じてModelを呼ぶ）
  ↓
models.py          → DBからデータを取得・更新
  ↓
views.py           → 取得したデータをTemplateに渡す
  ↓
templates/         → HTMLを生成
  ↓ レスポンス
ブラウザ

django_todo/
├── config/                     ← プロジェクト設定
│   ├── settings.py
│   ├── urls.py
│   └── templates/
│       └── base.html           ← 共通レイアウト
├── accounts/                   ← ユーザー認証アプリ
│   ├── views.py
│   ├── urls.py
│   └── templates/
│       ├── registration/
│       │   └── login.html
│       └── register.html
├── todo/                       ← タスク管理アプリ
│   ├── models.py
│   ├── views.py
│   ├── urls.py
│   └── templates/
│       └── index.html
├── create_tasks_table.py       ← タスクテーブル作成スクリプト
├── db.sqlite3                  ← 自動生成される
└── manage.py

django-admin startproject config . 
python manage.py startapp accounts
python manage.py startapp todo

INSTALLED_APPS = [
    ...
    'accounts.apps.AccountsConfig',  # 追加
    'todo.apps.TodoConfig',          # 追加
]

'DIRS': [BASE_DIR / 'config' / 'templates'],

LOGIN_REDIRECT_URL  = '/'                   # ログイン後、タスク一覧ページに遷移
LOGOUT_REDIRECT_URL = '/accounts/login/'    # ログアウト後、ログイン画面に遷移
LOGIN_URL           = '/accounts/login/'    # 未ログインで認証が必要な画面にアクセスした際、ログイン画面に遷移

python manage.py migrate

import sqlite3

db = sqlite3.connect("db.sqlite3", isolation_level=None) 

create_sql = """
    CREATE TABLE IF NOT EXISTS tasks (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        user_id INTEGER NOT NULL,
        title VARCHAR(200) NOT NULL,
        due_date DATE,
        priority VARCHAR(6) DEFAULT 'medium',
        completed INTEGER DEFAULT 0,
        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
        FOREIGN KEY (user_id) REFERENCES auth_user(id)
    );
"""

db.execute("PRAGMA foreign_keys = ON") 
db.execute(create_sql)
db.close()

python create_tasks_table.py

from django.db import connection

def dictfetchall(cursor):
    columns = [col[0] for col in cursor.description]
    return [dict(zip(columns, row)) for row in cursor.fetchall()]

class TaskManager:

    @classmethod
    def get_tasks_by_user(cls, user_id):
        with connection.cursor() as cursor:
            cursor.execute("""
                SELECT id, title, due_date, priority, completed, created_at
                FROM tasks
                WHERE user_id = %s
                ORDER BY
                    CASE priority WHEN 'high' THEN 1 WHEN 'medium' THEN 2 ELSE 3 END,
                    created_at DESC
            """, [user_id])
            return dictfetchall(cursor)

    @classmethod
    def create_task(cls, user_id, title, due_date, priority):
        with connection.cursor() as cursor:
            cursor.execute("""
                INSERT INTO tasks (user_id, title, due_date, priority)
                VALUES (%s, %s, %s, %s)
            """, [user_id, title, due_date or None, priority])

    @classmethod
    def toggle_complete(cls, task_id, user_id):
        with connection.cursor() as cursor:
            cursor.execute("""
                UPDATE tasks
                SET completed = CASE WHEN completed = 0 THEN 1 ELSE 0 END
                WHERE id = %s AND user_id = %s
            """, [task_id, user_id])

    @classmethod
    def get_task_by_id(cls, task_id, user_id):
        with connection.cursor() as cursor:
            cursor.execute("""
                SELECT id, title, user_id FROM tasks
                WHERE id = %s AND user_id = %s
            """, [task_id, user_id])
            results = dictfetchall(cursor)
            return results[0] if results else None

    @classmethod
    def delete_task(cls, task_id, user_id):
        with connection.cursor() as cursor:
            cursor.execute("""
                DELETE FROM tasks WHERE id = %s AND user_id = %s
            """, [task_id, user_id])

from django.shortcuts import render, redirect
from django.contrib.auth.forms import UserCreationForm

def register(request):
    if request.method == 'POST':
        form = UserCreationForm(request.POST)
        if form.is_valid():
            form.save()
            return redirect('login')
    else:
        form = UserCreationForm()
    return render(request, 'register.html', {'form': form})

from django.urls import path
from .views import register

urlpatterns = [
    path('register/', register, name='register'),
]

from django.shortcuts import render, redirect
from django.contrib.auth.decorators import login_required
from .models import TaskManager

@login_required
def todo_list(request):
    user_id = request.user.id  # Django標準認証ではrequest.userでユーザー情報を取得できる

    if request.method == 'POST':
        title    = request.POST.get('title', '').strip()
        due_date = request.POST.get('due_date') or None
        priority = request.POST.get('priority') or 'medium'

        if priority not in ['high', 'medium', 'low']:
            priority = 'medium'

        if not title:
            tasks = TaskManager.get_tasks_by_user(user_id)
            return render(request, 'index.html', {'tasks': tasks, 'error': 'タイトルを入力してください'})

        TaskManager.create_task(user_id, title, due_date, priority)
        return redirect('todo_list')

    tasks = TaskManager.get_tasks_by_user(user_id)
    return render(request, 'index.html', {'tasks': tasks})

@login_required
def toggle_complete(request, task_id):
    if request.method == 'POST':
        TaskManager.toggle_complete(task_id, request.user.id)  # ← toggle_complete を呼ぶ
    return redirect('todo_list')

@login_required
def todo_delete(request, task_id):
    if request.method == 'POST':
        TaskManager.delete_task(task_id, request.user.id)
    return redirect('todo_list')

from django.urls import path
from .views import todo_list, toggle_complete, todo_delete

urlpatterns = [
    path('',                        todo_list,       name='todo_list'),
    path('complete/<int:task_id>/', toggle_complete, name='toggle_complete'),
    path('delete/<int:task_id>/',   todo_delete,     name='todo_delete'),
]

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

urlpatterns = [
    path('admin/', admin.site.urls),
    path('accounts/', include('django.contrib.auth.urls')),  # ログイン・ログアウト
    path('accounts/', include('accounts.urls')),             # ユーザー登録
    path('', include('todo.urls')),
]

<!DOCTYPE html>
<html lang="ja">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/css/bootstrap.min.css" rel="stylesheet">
  <title>{% block title %}{% endblock %} | ToDoリスト</title>
</head>
<body>
  <nav class="navbar navbar-expand-lg bg-body-tertiary">
    <div class="container-fluid">
      <a class="navbar-brand" href="{% url 'todo_list' %}">📝 ToDoリスト</a>
      <ul class="navbar-nav ms-auto">
        {% if user.is_authenticated %}
          <li class="nav-item"><span class="nav-link">{{ user.username }}</span></li>
          <li class="nav-item">
            <form method="POST" action="{% url 'logout' %}">
              {% csrf_token %}
              <button type="submit" class="nav-link btn btn-link border-0 bg-transparent">
                ログアウト
              </button>
            </form>
          </li>
        {% else %}
          <li class="nav-item"><a class="nav-link" href="{% url 'login' %}">ログイン</a></li>
          <li class="nav-item"><a class="nav-link" href="{% url 'register' %}">ユーザー登録</a></li>
        {% endif %}
      </ul>
    </div>
  </nav>
  <div class="container mt-4">
    {% block content %}{% endblock %}
  </div>
  <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0/dist/js/bootstrap.bundle.min.js"></script>
</body>
</html>

{% extends 'base.html' %}
{% block title %}ログイン{% endblock %}
{% block content %}
<h2>ログイン</h2>
{% if form.errors %}<p class="text-danger">ユーザー名またはパスワードが正しくありません</p>{% endif %}
<form method="POST">
  {% csrf_token %}
  <div class="mb-3">
    <label>ユーザー名</label>
    <input type="text" name="username" class="form-control" required>
  </div>
  <div class="mb-3">
    <label>パスワード</label>
    <input type="password" name="password" class="form-control" required>
  </div>
  <button type="submit" class="btn btn-primary">ログイン</button>
  <a href="{% url 'register' %}" class="btn btn-outline-secondary ms-2">ユーザー登録はこちら</a>
</form>
{% endblock %}

{% extends 'base.html' %}
{% block title %}ユーザー登録{% endblock %}
{% block content %}
<h2>ユーザー登録</h2>
<form method="POST">
  {% csrf_token %}
  {{ form.as_p }}
  <button type="submit" class="btn btn-primary">登録</button>
  <a href="{% url 'login' %}" class="btn btn-outline-secondary ms-2">ログインはこちら</a>
</form>
{% endblock %}

{% extends 'base.html' %}
{% block title %}タスク一覧{% endblock %}
{% block content %}

<h2>タスク一覧</h2>
{% if error %}<p class="text-danger">{{ error }}</p>{% endif %}

<form method="POST" class="mb-4">
  {% csrf_token %}
  <div class="row g-2 align-items-end">
    <div class="col-md-4">
      <label>タイトル</label>
      <input type="text" name="title" class="form-control" placeholder="タスクを入力" required>
    </div>
    <div class="col-md-3">
      <label>期限</label>
      <input type="date" name="due_date" class="form-control">
    </div>
    <div class="col-md-3">
      <label>優先度</label>
      <select name="priority" class="form-select">
        <option value="high">高</option>
        <option value="medium" selected>中</option>
        <option value="low">低</option>
      </select>
    </div>
    <div class="col-md-2">
      <button type="submit" class="btn btn-primary w-100">追加</button>
    </div>
  </div>
</form>

<table class="table table-hover">
  <thead class="table-dark">
    <tr><th>完了</th><th>タイトル</th><th>期限</th><th>優先度</th><th></th></tr>
  </thead>
  <tbody>
    {% for task in tasks %}
    <tr>
      <td>
        <form method="POST" action="{% url 'toggle_complete' task.id %}">
          {% csrf_token %}
          <button type="submit" class="btn btn-sm btn-outline-secondary">
            {% if task.completed %}✅{% else %}⬜{% endif %}
          </button>
        </form>
      </td>
      <td {% if task.completed %}style="text-decoration: line-through; color: gray;"{% endif %}>
        {{ task.title }}
      </td>
      <td>{{ task.due_date|default:"-" }}</td>
      <td>
        {% if task.priority == 'high' %}<span class="badge bg-danger">高</span>
        {% elif task.priority == 'medium' %}<span class="badge bg-warning text-dark">中</span>
        {% else %}<span class="badge bg-success">低</span>{% endif %}
      </td>
      <td>
        <form method="POST" action="{% url 'todo_delete' task.id %}">
          {% csrf_token %}
          <button type="submit" class="btn btn-sm btn-outline-danger">削除</button>
        </form>
      </td>
    </tr>
    {% empty %}
    <tr><td colspan="5" class="text-center">タスクはありません</td></tr>
    {% endfor %}
  </tbody>
</table>

{% endblock %}

python manage.py runserver