Flask-Login

Flask-Login 提供用戶會話管理，處理常見的登錄、退出和註冊的任務。

Flask-Login 沒有綁定數據庫,可以從數據庫回調用戶對象。

安裝flask-login

pip install flask-login

結構

|-- app/
|   |-- __init__.py
|   |-- forms.py
|   |-- models.py
|   |-- routes.py
|   `-- templates/
|       |-- base.html
|       |-- index.html
|       |-- login.html
|       `-- register.html
|-- app.db
|-- config.py
`-- microblog.py
 

環境變量

安裝python-dotenv，避免了每次運行代碼都要定義環境變量

pip install python-dotenv

根目錄新建.flaskenv環境變量文件
.flaskenv：

FLASK_APP=microblog.py

microblog.py:

from app import app, db
from app.models import User, Post


@app.shell_context_processor
def make_shell_context():
    return {‘db‘: db, ‘User‘: User, ‘Post‘: Post}
 

配置項

import os
basedir = os.path.abspath(os.path.dirname(__file__))


class Config(object):
    SECRET_KEY = os.environ.get(‘SECRET_KEY‘) or ‘you-will-never-guess‘
    SQLALCHEMY_DATABASE_URI = os.environ.get(‘DATABASE_URL‘) or         ‘sqlite:///‘ + os.path.join(basedir, ‘app.db‘)
    SQLALCHEMY_TRACK_MODIFICATIONS = False
 

app.dp項目運行後產生

初始化模塊

app/__init__.py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_migrate import Migrate
from config import Config
from flask_login import LoginManager

app = Flask(__name__)
app.config.from_object(Config)
db = SQLAlchemy(app)
migrate = Migrate(app, db)
login = LoginManager(app)
login.login_view = ‘login‘

from app import routes, models

用戶加載模塊

用戶加載模塊,完成如下2個功能：

1. 定義用戶數據庫模型
2. 加載數據庫匹配用戶

註意事項：

使用Flask-Login的user類必須實現下列屬性方法：

如果繼承UserMixin類，則默認實現了上述方法；

app/models.py

from datetime import datetime
from app import db, login
from werkzeug.security import generate_password_hash, check_password_hash
from flask_login import UserMixin


class User(UserMixin,db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), index=True, unique=True)
    email = db.Column(db.String(120), index=True, unique=True)
    password_hash = db.Column(db.String(128))
    posts = db.relationship(‘Post‘, backref=‘author‘, lazy=‘dynamic‘)

    def __repr__(self):
        return ‘<User {}>‘.format(self.username)

    def set_password(self, password):
        self.password_hash = generate_password_hash(password)

    def check_password(self, password):
        return check_password_hash(self.password_hash, password)

@login.user_loader
def load_user(id):
    return User.query.get(int(id))

class Post(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    body = db.Column(db.String(140))
    timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
    user_id = db.Column(db.Integer, db.ForeignKey(‘user.id‘))

    def __repr__(self):
        return ‘<Post {}>‘.format(self.body)

路由和視圖函數

• 用戶登陸
• 用戶註銷
• 用戶註冊

app/routes.py

from flask import render_template, flash, redirect, url_for, request
from flask_login import login_user, logout_user, current_user, login_required
from werkzeug.urls import url_parse
from app import app, db
from app.forms import LoginForm, RegistrationForm
from app.models import User


@app.route(‘/‘)
@app.route(‘/index‘)
@login_required
def index():
    posts = [
        {
            ‘author‘: {‘username‘: ‘John‘},
            ‘body‘: ‘Beautiful day in Portland!‘
        },
        {
            ‘author‘: {‘username‘: ‘Susan‘},
            ‘body‘: ‘The Avengers movie was so cool!‘
        }
    ]
    return render_template(‘index.html‘, title=‘Home‘, posts=posts)


@app.route(‘/login‘, methods=[‘GET‘, ‘POST‘])
def login():
    if current_user.is_authenticated:
        return redirect(url_for(‘index‘))
    form = LoginForm()
    if form.validate_on_submit():
        user = User.query.filter_by(username=form.username.data).first()
        if user is None or not user.check_password(form.password.data):
            flash(‘Invalid username or password‘)
            return redirect(url_for(‘login‘))
        login_user(user, remember=form.remember_me.data)
        next_page = request.args.get(‘next‘)
        if not next_page or url_parse(next_page).netloc != ‘‘:
            next_page = url_for(‘index‘)
        return redirect(next_page)
    return render_template(‘login.html‘, title=‘Sign In‘, form=form)


@app.route(‘/logout‘)
def logout():
    logout_user()
    return redirect(url_for(‘index‘))


@app.route(‘/register‘, methods=[‘GET‘, ‘POST‘])
def register():
    if current_user.is_authenticated:
        return redirect(url_for(‘index‘))
    form = RegistrationForm()
    if form.validate_on_submit():
        user = User(username=form.username.data, email=form.email.data)
        user.set_password(form.password.data)
        db.session.add(user)
        db.session.commit()
        flash(‘Congratulations, you are now a registered user!‘)
        return redirect(url_for(‘login‘))
    return render_template(‘register.html‘, title=‘Register‘, form=form)

表單

實現2個功能：

• 登陸驗證
• 用戶註冊

app/forms.py：

from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, BooleanField, SubmitField
from wtforms.validators import ValidationError, DataRequired, Email, EqualTo
from app.models import User


class LoginForm(FlaskForm):
    username = StringField(‘Username‘, validators=[DataRequired()])
    password = PasswordField(‘Password‘, validators=[DataRequired()])
    remember_me = BooleanField(‘Remember Me‘)
    submit = SubmitField(‘Sign In‘)


class RegistrationForm(FlaskForm):
    username = StringField(‘Username‘, validators=[DataRequired()])
    email = StringField(‘Email‘, validators=[DataRequired(), Email()])
    password = PasswordField(‘Password‘, validators=[DataRequired()])
    password2 = PasswordField(
        ‘Repeat Password‘, validators=[DataRequired(), EqualTo(‘password‘)])
    submit = SubmitField(‘Register‘)

    def validate_username(self, username):
        user = User.query.filter_by(username=username.data).first()
        if user is not None:
            raise ValidationError(‘Please use a different username.‘)

    def validate_email(self, email):
        user = User.query.filter_by(email=email.data).first()
        if user is not None:
            raise ValidationError(‘Please use a different email address.‘)

模板

app/templates/base.html：基本模板，用於做父類提供繼承

<html>
    <head>
        {% if title %}
        <title>{{ title }} - Microblog</title>
        {% else %}
        <title>Welcome to Microblog</title>
        {% endif %}
    </head>
    <body>
        <div>
            Microblog:
            <a href="{{ url_for(‘index‘) }}">Home</a>
            {% if current_user.is_anonymous %}
            <a href="{{ url_for(‘login‘) }}">Login</a>
            {% else %}
            <a href="{{ url_for(‘logout‘) }}">Logout</a>
            {% endif %}
        </div>
        <hr>
        {% with messages = get_flashed_messages() %}
        {% if messages %}
        <ul>
            {% for message in messages %}
            <li>{{ message }}</li>
            {% endfor %}
        </ul>
        {% endif %}
        {% endwith %}
        {% block content %}{% endblock %}
    </body>
</html>

app/templates/index.html：起始頁面

{% extends "base.html" %}

{% block content %}
    <h1>Hi, {{ current_user.username }}!</h1>
    {% for post in posts %}
    <div><p>{{ post.author.username }} says: <b>{{ post.body }}</b></p></div>
    {% endfor %}
{% endblock %}

app/templates/register.html：用戶註冊

{% extends "base.html" %}

{% block content %}
    <h1>Register</h1>
    <form action="" method="post">
        {{ form.hidden_tag() }}
        <p>
            {{ form.username.label }}<br>
            {{ form.username(size=32) }}<br>
            {% for error in form.username.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>
            {{ form.email.label }}<br>
            {{ form.email(size=64) }}<br>
            {% for error in form.email.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>
            {{ form.password.label }}<br>
            {{ form.password(size=32) }}<br>
            {% for error in form.password.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>
            {{ form.password2.label }}<br>
            {{ form.password2(size=32) }}<br>
            {% for error in form.password2.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.submit() }}</p>
    </form>
{% endblock %}

app/templates/login.html：遊客請登陸

{% extends "base.html" %}

{% block content %}
    <h1>Sign In</h1>
    <form action="" method="post" novalidate>
        {{ form.hidden_tag() }}
        <p>
            {{ form.username.label }}<br>
            {{ form.username(size=32) }}<br>
            {% for error in form.username.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>
            {{ form.password.label }}<br>
            {{ form.password(size=32) }}<br>
            {% for error in form.password.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.remember_me() }} {{ form.remember_me.label }}</p>
        <p>{{ form.submit() }}</p>
    </form>

    <p>New User? <a href="{{ url_for(‘register‘) }}">Click to Register!</a></p>
{% endblock %}

項目運行

到項目根目錄

PS D:\Days\Flask-Login> flask run
 * Serving Flask-SocketIO app "microblog.py"
 * Forcing debug mode off
 * Serving Flask app "microblog.py"
 * Environment: production
   WARNING: Do not use the development server in a production environment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
127.0.0.1 - - [30/Nov/2018 11:22:44] "GET /login?next=%2F HTTP/1.1" 200 -

瀏覽器打開：http://localhost:5000

Flask-Login用戶登陸