Flask 系列之 LoginManager

说明

• 操作系统：Windows 10
• Python 版本：3.7x
• 虚拟环境管理器：virtualenv
• 代码编辑器：VS Code

实验目标

通过使用 flask-login 进行会话管理的相关操作，并完成用户合法性登陆和退出。

安装

pip install flask-login

使用

首先，在 todlist\app\__init__.py 中创建 login_manager，并进行相关配置，示例代码如下所示：

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bootstrap import Bootstrap
from flask_login import LoginManager
from config import Config

app = Flask(__name__)
app.config.from_object(Config)

db = SQLAlchemy(app)
bootstrap = Bootstrap(app)

login_manager = LoginManager(app)
login_manager.login_view = 'login'
login_manager.login_message = '你必须登陆后才能访问该页面'
login_manager.login_message_category = "info"

from app import views

然后，完善我们 todolist\models.py 中关于用户密码校验部分的逻辑处理，示例代码如下所示：

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

@login_manager.user_loader
def load_user(user_id):
    user = User.query.get(user_id)
    return user

class User(db.Model, UserMixin):
    __tablename__ = 'users'
    # __table_args__ = {"useexisting": True}

    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(20), nullable=False, unique=True)
    email = db.Column(db.String(120), nullable=False, unique=True)
    pwd = db.Column(db.String(120), nullable=False)

    things = db.relationship('Thing', backref='User', lazy='dynamic')

    def __repr__(self):
        return "<User %r>" % self.name

    def generate_password_hash(self, pwd):
        self.pwd = generate_password_hash(pwd)

    def check_password_hash(self, pwd):
        return check_password_hash(self.pwd, pwd)

class Thing(db.Model):
    __tablename__ = 'things'
    # __table_args__ = {"useexisting": True}

    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
    title = db.Column(db.String(20), nullable=False)
    text = db.Column(db.Text, nullable=False)
    add_date = db.Column(db.DateTime, default=datetime.now)

    def __repr__(self):
        return "<Todo %r>" % self.id

然后在 todolist\forms.py 中添加一个用于处理用户登陆的表单提交类，示例代码如下所示：

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

class RegisterForm(FlaskForm):
    username = StringField('用户名：', validators=[
                           DataRequired(), Length(min=6, max=20)])
    email = StringField('邮箱：', validators=[DataRequired(), Email()])
    pwd = PasswordField('密码：', validators=[
        DataRequired(), Length(min=8, max=120)])
    confirm = PasswordField('确认密码：', validators=[
                            DataRequired(), EqualTo('pwd')])
    submit = SubmitField('提交')

    def validate_username(self, username):
        user = User.query.filter_by(name=username.data).first()
        if user:
            raise ValidationError("用户昵称已存在。")

    def validate_email(self, email):
        user = User.query.filter_by(email=email.data).first()
        if user:
            raise ValidationError('邮箱已存在.')

class LoginForm(FlaskForm):
    username = StringField('用户名：', validators=[
                           DataRequired(), Length(min=6, max=20)])
    password = PasswordField('密码：', validators=[DataRequired()])
    submit = SubmitField('登陆')

    def validate_username(self, username):
        user = User.query.filter_by(name=username.data)
        if not user:
            raise ValidationError('用户名不存在。')

然后修改我们的 todolist\app\views.py ，添加用户登陆和登出的路由处理函数，示例代码如下所示：

from flask import render_template, redirect, url_for, flash
from flask_login import login_user, login_required, current_user, logout_user
from app import app, db
from forms import RegisterForm, LoginForm
from models import User

@app.context_processor
def inject_user():
    user = User.query.first()
    return dict(user=user)

@app.route('/')
@app.route('/index')
def index():
    if not current_user.is_authenticated:
        return redirect(url_for('login'))
    return render_template('index.html', title="首页")

@app.route('/login', methods=['POST', 'GET'])
def login():
    form = LoginForm()
    if form.validate_on_submit():
        name = form.username.data
        pwd = form.password.data
        user = User.query.filter_by(name=name).first()
        if user and user.check_password_hash(pwd):
            login_user(user)
            flash('登陆成功。', category='info')
            return redirect(url_for('index'))
        else:
            flash("密码或账户错误。", category='error')
    return render_template('login.html', title='登录', form=form)

@app.route('/logout')
@login_required
def logout():
    logout_user()
    flash('再见！')
    return redirect(url_for('login'))

@app.route('/register', methods=['POST', 'GET'])
def register():
    form = RegisterForm()
    if form.validate_on_submit():
        username = form.username.data
        email = form.email.data
        pwd = form.pwd.data
        user = User(name=username, email=email)
        user.generate_password_hash(pwd)
        db.session.add(user)
        db.session.commit()
        flash('注册成功', category='info')
        return redirect(url_for('login'))
    return render_template('register.html', title='注册', form=form)

接着，修改我们 todolist\app\templates\login.html 页面，添加用户登陆的表单，示例代码如下所示：

{% extends 'base.html' %} {% block content %}
<h1>登录页面</h1>
{% from 'bootstrap/form.html' import render_form %} {{ render_form(form) }}
{% endblock %}

修改我们的 todolist\app\templates\nav.html 页面，完善菜单栏的逻辑控制，示例代码如下所示：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
    <div class="container">
        <a class="navbar-brand" href="#">愿望清单</a>

        <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent"
            aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
            <span class="navbar-toggler-icon"></span>
        </button>

        <div class="collapse navbar-collapse" id="navbarSupportedContent">
            <ul class="navbar-nav mr-auto">
                <li class="nav-item {% if request.endpoint == 'index' %} active {% endif %}">
                    <a class="nav-link" href="{{ url_for('index') }}">首页<span class="sr-only">(current)</span></a>
                </li>
            </ul>

            <ul class="navbar-nav">
                {% if current_user.is_authenticated and user %}
                <li class="nav-item {% if request.endpoint == 'logout' %} active {% endif %}">
                    <a class="nav-link" href="{{ url_for('logout') }}">登出</a>
                </li>
                {% else %}
                <li class="nav-item {% if request.endpoint == 'login' %} active {% endif %}">
                    <a class="nav-link" href="{{ url_for('login') }}">登录</a>
                </li>
                <li class="nav-item {% if request.endpoint == 'register' %} active {% endif %}">
                    <a class="nav-link" href="{{ url_for('register') }}">注册</a>
                </li>
                {% endif %}
            </ul>
        </div>
    </div>
</nav>

修改我们的 todolist\app\templates\index.html 页面，显示当前登陆的用户，示例代码如下所示：

{% extends 'base.html' %} {% block content %}

{% if current_user.is_authenticated and user %}
<h1>{{ current_user.name }},欢迎回来</h1>
{% else %}
<h1>首页</h1>
{% endif %}

{% endblock %}

此时，当我们运行起我们的网站后进入注册页面 http://127.0.0.1:5000 就可以进行用户的注册、登陆和登出了。

参考连接

• Flask-Login