Minimum viable product

flaskr/__init__.py

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+import os
+from flask import Flask
+
+def create_app(test_config=None):
+    # create and configure the app
+    app = Flask(__name__,instance_relative_config=True)
+    app.config.from_mapping(
+        SECRET_KEY='dev',
+        DATABASE=os.path.join(app.instance_path, 'flaskr.sqlite'),
+    )
+
+    if test_config is None:
+        # load the instance config, if it exists, when not testing
+        app.config.from_pyfile('config.py', silent=True)
+    else:
+        # load the test config if passed in
+        app.config.from_mapping(test_config)
+
+    # ensure the instance folder exists
+    try:
+        os.makedirs(app.instance_path)
+    except OSError:
+        pass
+
+    # a simple page that says hello
+    @app.route('/hello')
+    def hello():
+        return 'Hello, World!'
+
+    from . import db
+    db.init_app(app)
+
+    from . import auth
+    app.register_blueprint(auth.bp)
+
+    from . import blog
+    app.register_blueprint(blog.bp)
+    app.add_url_rule('/', endpoint='index')
+
+    return app

flaskr/auth.py

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+import functools
+
+from flask import (
+    Blueprint, flash, g, redirect, render_template, request, session, url_for
+)
+from werkzeug.security import check_password_hash, generate_password_hash
+
+from flaskr.db import get_db
+
+bp = Blueprint('auth', __name__, url_prefix='/auth')
+
+@bp.route('/register', methods=('GET', 'POST'))
+def register():
+    if request.method == 'POST':
+        username = request.form['username']
+        password = request.form['password']
+        db = get_db()
+        error = None
+
+        if not username:
+            error = "Username is required."
+        elif not password:
+            error = "Password is required."
+
+        if error is None:
+            try:
+                db.execute(
+                    "INSERT INTO user (username, password) VALUES (?, ?)",
+                    (username, generate_password_hash(password)),
+                )
+                db.commit()
+            except db.IntegrityError:
+                error = f"User {username} is already registered."
+            else:
+                return redirect(url_for("auth.login"))
+
+        flash(error)
+
+    return render_template('auth/register.html')
+
+@bp.route('/login', methods=('GET', 'POST'))
+def login():
+    if request.method == 'POST':
+        username = request.form['username']
+        password = request.form['password']
+        db = get_db()
+        error = None
+        user = db.execute(
+            'SELECT * FROM user WHERE username = ?', (username,)
+        ).fetchone()
+
+        if user is None:
+            error = 'Incorrect username.'
+        elif not check_password_hash(user['password'], password):
+            error = 'Incorrect password.'
+
+        if error is None:
+            session.clear()
+            session['user_id'] = user['id']
+            return redirect(url_for('index'))
+
+        flash(error)
+
+    return render_template('auth/login.html')
+
+@bp.before_app_request
+def load_logged_in_user():
+    user_id = session.get('user_id')
+
+    if user_id is None:
+        g.user = None
+    else:
+        g.user = get_db().execute(
+            'SELECT * FROM user WHERE id = ?', (user_id,)
+        ).fetchone()
+
+@bp.route('/logout')
+def logout():
+    session.clear()
+    return redirect(url_for('index'))
+
+def login_required(view):
+    @functools.wraps(view)
+    def wrapped_view(**kwargs):
+        if g.user is None:
+            return redirect(url_for('auth.login'))
+
+        return view(**kwargs)
+
+    return wrapped_view

flaskr/blog.py

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+from flask import (
+    Blueprint, flash, g, redirect, render_template, request, url_for
+)
+from werkzeug.exceptions import abort
+
+from flaskr.auth import login_required
+from flaskr.db import get_db
+
+import markdown
+
+bp = Blueprint('blog', __name__)
+
+@bp.route('/')
+def index():
+    db = get_db()
+    db_posts = db.execute(
+        'SELECT p.id, title, body, created, author_id, username'
+        ' FROM post p JOIN user u ON p.author_id = u.id'
+        ' ORDER BY created DESC'
+    ).fetchall()
+    posts = []
+    for post in db_posts:
+        post = dict(post)
+        post['body'] = markdown.markdown(post['body'])
+        posts.append(post)
+    return render_template('blog/index.html', posts=posts)
+
+@bp.route('/create',methods=('GET', 'POST'))
+@login_required
+def create():
+    if request.method == 'POST':
+        title = request.form['title']
+        body = request.form['body']
+        error = None
+
+        if not title:
+            error = 'Title is required.'
+
+        if error is not None:
+            flash(error)
+        else:
+            db = get_db()
+            db.execute(
+                'INSERT INTO post (title,  body, author_id)'
+                ' VALUES (?, ?, ?)',
+                (title, body, g.user['id'])
+            )
+            db.commit()
+            return redirect(url_for('blog.index'))
+
+    return render_template('blog/create.html')
+
+def get_post(id, check_author=True):
+    post = get_db().execute(
+        'SELECT p.id, title, body, created, author_id, username'
+        ' FROM post p JOIN user u ON p.author_id = u.id'
+        ' WHERE p.id = ?',
+        (id,)
+    ).fetchone()
+
+    if post is None:
+        abort(404, f"Post id {id} doesn't exist.")
+
+    if check_author and post['author_id'] != g.user['id']:
+        abort(403)
+
+    return post
+
+@bp.route('/<int:id>/update', methods=('GET', 'POST'))
+@login_required
+def update(id):
+    post = get_post(id)
+
+    if request.method == 'POST':
+        title = request.form['title']
+        body = request.form['body']
+        error = None
+
+        if not title:
+            error = 'Title is required.'
+
+        if error is not None:
+            flash(error)
+        else:
+            db = get_db()
+            db.execute(
+                'UPDATE post SET title = ?, body = ?'
+                ' WHERE id = ?',
+                (title, body, id)
+            )
+            db.commit()
+            return redirect(url_for('blog.index'))
+
+    return render_template('blog/update.html', post=post)
+
+@bp.route('/<int:id>/delete', methods=('POST',))
+@login_required
+def delete(id):
+    get_post(id)
+    db = get_db()
+    db.execute('DELETE FROM post WHERE id = ?',(id,))
+    db.commit()
+    return redirect(url_for('blog.index'))

flaskr/db.py

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+import sqlite3
+
+import click
+from flask import current_app, g
+
+def get_db():
+    if 'db' not in g:
+        g.db = sqlite3.connect(
+            current_app.config['DATABASE'],
+            detect_types=sqlite3.PARSE_DECLTYPES
+        )
+        g.db.row_factory = sqlite3.Row
+
+    return g.db
+
+def close_db(e=None):
+    db = g.pop('db', None)
+
+    if db is not None:
+        db.close()
+def init_db():
+    db = get_db()
+
+    with current_app.open_resource('schema.sql') as f:
+        db.executescript(f.read().decode('utf-8'))
+
+@click.command('init-db')
+def init_db_command():
+    """Clear the existing data and create new tables."""
+    init_db()
+    click.echo("Initialized the database.")
+
+def init_app(app):
+    app.teardown_appcontext(close_db)
+    app.cli.add_command(init_db_command)

flaskr/schema.sql

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+DROP TABLE IF EXISTS user;
+DROP TABLE IF EXISTS post;
+
+CREATE TABLE user (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  username TEXT UNIQUE NOT NULL,
+  password TEXT NOT NULL
+);
+
+CREATE TABLE post (
+  id INTEGER PRIMARY KEY AUTOINCREMENT,
+  author_id INTEGER NOT NULL,
+  created TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  title TEXT NOT NULL,
+  body TEXT NOT NULL,
+  FOREIGN KEY (author_id) REFERENCES user (id)
+);

flaskr/static/style.css

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+html { font-family: sans-serif; background: #eee; padding: 1rem; }
+body { max-width: 960px; margin: 0 auto; background: white; }
+h1 { font-family: serif; color: #377ba8; margin: 1rem 0; }
+a { color: #377ba8; }
+hr { border: none; border-top: 1px solid lightgray; }
+nav { background: lightgray; display: flex; align-items: center; padding: 0 0.5rem; }
+nav h1 { flex: auto; margin: 0; }
+nav h1 a { text-decoration: none; padding: 0.25rem 0.5rem; }
+nav ul  { display: flex; list-style: none; margin: 0; padding: 0; }
+nav ul li a, nav ul li span, header .action { display: block; padding: 0.5rem; }
+.content { padding: 0 1rem 1rem; }
+.content > header { border-bottom: 1px solid lightgray; display: flex; align-items: flex-end; }
+.content > header h1 { flex: auto; margin: 1rem 0 0.25rem 0; }
+.flash { margin: 1em 0; padding: 1em; background: #cae6f6; border: 1px solid #377ba8; }
+.post > header { display: flex; align-items: flex-end; font-size: 0.85em; }
+.post > header > div:first-of-type { flex: auto; }
+.post > header h1 { font-size: 1.5em; margin-bottom: 0; }
+.post .about { color: slategray; font-style: italic; }
+.post .body { white-space: pre-line; }
+.content:last-child { margin-bottom: 0; }
+.content form { margin: 1em 0; display: flex; flex-direction: column; }
+.content label { font-weight: bold; margin-bottom: 0.5em; }
+.content input, .content textarea { margin-bottom: 1em; }
+.content textarea { min-height: 12em; resize: vertical; }
+input.danger { color: #cc2f2e; }
+input[type=submit] { align-self: start; min-width: 10em; }

flaskr/templates/auth/login.html

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+{% extends 'base.html' %}
+
+{% block header %}
+  <h1>{% block title %}Log In{% endblock%}</h1>
+{% endblock %}
+
+{% block content %}
+  <form method="post">
+    <label for="username">Username</label>
+    <input name="username" id="username" required>
+    <label for="password">Password</label>
+    <input type="password" name="password" id="password" required>
+    <input type="submit" value="Log In">
+  </form>
+{% endblock %}

flaskr/templates/auth/register.html

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+{% extends 'base.html' %}
+
+{% block header %}
+  <h1>{% block title %}Register{% endblock%}</h1>
+{% endblock %}
+
+{% block content %}
+  <form method="post">
+    <label for="username">Username</label>
+    <input name="username" id="username" required>
+    <label for="password">Password</label>
+    <input type="password" name="password" id="password" required>
+    <input type="submit" value="Register">
+  </form>
+{% endblock %}

flaskr/templates/base.html

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+<!doctype html>
+<title>{% block title %}{% endblock %} - Flaskr</title>
+<link rel="stylesheet" href="{{ url_for('static', filename='style.css') }}">
+<link rel="icon" type="image/png" href="{{ url_for('static', filename='favicon.png') }}">
+<nav>
+  <h1>Flaskr</h1>
+  <ul>
+    {% if g.user %}
+      <li><span>{{ g.user['username'] }}</span>
+      <li><a href="{{ url_for('auth.logout') }}">Log Out</a>
+    {% else %}
+      <li><a href="{{ url_for('auth.register') }}">Register</a>
+      <li><a href="{{ url_for('auth.login') }}">Log In</a>
+    {% endif %}
+  </ul>
+</nav>
+<section class="content">
+  <header>
+    {% block header %}{% endblock %}
+  </header>
+  {% for message in get_flashed_messages() %}
+    <div class="flash">{{ message }}</div>
+  {% endfor %}
+  {% block content %}{% endblock %}
+</section>

flaskr/templates/blog/create.html

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+{% extends 'base.html' %}
+
+{% block header %}
+  <h1>{% block title %}New Post{% endblock %}</h1>
+{% endblock %}
+
+{% block content %}
+  <form method="post">
+    <label for="title">Title</label>
+    <input name="title" id="title" value="{{ request.form['title'] }}" required>
+    <label for="body">Body</label>
+    <textarea name="body" id="body">{{ request.form['body'] }}</textarea>
+    <input type="submit" value="Save">
+  </form>
+{% endblock %}

flaskr/templates/blog/index.html

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+{% extends 'base.html' %}
+
+{% block header %}
+  <h1>{% block title %}Posts{% endblock %}</h1>
+  {% if g.user %}
+    <a class="action" href="{{ url_for('blog.create') }}">New</a>
+  {% endif %}
+{% endblock %}
+
+{% block content %}
+  {% for post in posts %}
+    <article class="post">
+      <header>
+	<div>
+	  <h1>{{ post['title'] }}</h1>
+	  <div class="about">by {{ post['username'] }} on {{ post['created'].strftime('%Y-%m-%d') }}</div>
+	</div>
+	{% if g.user['id'] == post['author_id'] %}
+	  <a class="action" href="{{ url_for('blog.update', id=post['id']) }}">Edit</a>
+	  {% endif %}
+      </header>
+      <p class="body">{{ post['body']|safe }}</p>
+    </article>
+    {% if not loop.last %}
+      <hr>
+    {% endif %}
+  {% endfor %}
+{% endblock %}    

flaskr/templates/blog/update.html

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+{% extends 'base.html' %}
+
+{% block header %}
+  <h1>{% block title %}Edit "{{ post['title'] }}"{% endblock %}</h1>
+{% endblock %}
+
+{% block content %}
+  <form method="post">
+    <label for="title">Title</label>
+    <input name="title" id="title"
+      value="{{ request.form['title'] or post['title'] }}" required>
+    <label for="body">Body</label>
+    <textarea name="body" id="body">{{ request.form['body'] or post['body'] }}</textarea>
+    <input type="submit" value="Save">
+  </form>
+  <hr>
+  <form action="{{ url_for('blog.delete', id=post['id']) }}" method="post">
+    <input class="danger" type="submit" value="Delete" onclick="return confirm('Are you sure?');">
+  </form>
+{% endblock %}

flaskr/templates/hello.html

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+<!doctype html>
+<title>Hello from Flask</title>
+{% if name %}
+  <h1>Hello {{ name }}!</h1>
+{% else %}
+  <h1>Hello, World!</h1>
+{% endif %}