用Python、Flask和MySQL进行用户登录和注册的方法

方石剑
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在本教程中，我们将解释如何用Python、Flask和MySQL实现用户登录和注册。

用户登录和注册是任何Web应用程序中用户模块的一个重要功能。用户可以创建自己的账户并登录以访问用户部分。

在本教程中，我们将实现用户登录、注销和注册的功能。我们将使用Flask 框架和Python 来创建带有登录和注册表格的Web应用程序，并使用MySQL 数据库实现功能。

因此，让我们继续使用Python、Flask和MySQL实现登录和注册。

需要的模块

我们将使用以下模块来实现登录和注册功能：

  • Flask。Flask是一个轻量级的WSGI网络应用框架，用于使用Python创建网络应用。它可以用下面的命令来安装。
pip install Flask
  • Flask-MySQLdb。Flask-MySQLdb为Flask应用程序提供MySQL连接。由于我们将使用MySQL 数据库开发功能，所以我们需要安装这个模块来连接数据库。它可以用下面的命令来安装。
pip install flask-mysqldb

创建MySQL数据库

我们需要创建MySQL数据库，然后用user 表来存储用户信息。

我们将使用下面的查询创建user 表。

CREATE TABLE `user` (
  `userid` int(11) NOT NULL,
  `name` varchar(100) NOT NULL,
  `email` varchar(100) NOT NULL,
  `password` varchar(255) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

ALTER TABLE `user`
  ADD PRIMARY KEY (`userid`);

我们还插入一些用户记录，以检查登录功能。

INSERT INTO `user` (`userid`, `name`, `email`, `password`) VALUES
(1, 'Jhon smith', 'smith@webdamn.com', '123'),
(2, 'Adam William', 'adam@webdamn.com', '123');

实现用户登录和注册

我们将创建项目目录login-register-app ，并安装所有需要的模块。

然后我们将创建app.py Python文件并导入所需的模块，如Falsk,flask-mysqldb 和辅助函数。

我们还将在proect文件夹中创建目录templates ，以保存模板文件。

然后我们将在app.py 中创建函数login() 来实现用户登录功能。

@app.route('/login', methods =['GET', 'POST'])
def login():
    mesage = ''
    if request.method == 'POST' and 'email' in request.form and 'password' in request.form:
        email = request.form['email']
        password = request.form['password']
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM user WHERE email = % s AND password = % s', (email, password, ))
        user = cursor.fetchone()
        if user:
            session['loggedin'] = True
            session['userid'] = user['userid']
            session['name'] = user['name']
            session['email'] = user['email']
            mesage = 'Logged in successfully !'
            return render_template('user.html', mesage = mesage)
        else:
            mesage = 'Please enter correct email / password !'
    return render_template('login.html', mesage = mesage)

我们将在templates 目录下创建login.html 模板文件并创建登录表单。

这里是完整的.login.html 文件。

<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>User Login Form</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css">
</head>
<body>	
<div class="container">
	<h2>User Login</h2>
	<form action="{{ url_for('login') }}" method="post">
	    {% if mesage is defined and mesage %}
			<div class="alert alert-warning">{{ mesage }}</div>
		{% endif %}
		<div class="form-group">
			<label for="email">Email:</label>
			<input type="email" class="form-control" id="email" name="email" placeholder="Enter email" name="email">
		</div>
		<div class="form-group">
			<label for="pwd">Password:</label>
			<input type="password" class="form-control" id="password" name="password" placeholder="Enter password" name="pswd">
		</div>    
		<button type="submit" class="btn btn-primary">Login</button>
		<p class="bottom">Dont't have an account?  <a class="bottom" href="{{url_for('register')}}"> Register here</a></p>
	</form>
</div>
</body>
</html>

当用户登录成功后，它将重定向到user.html ，显示登录页面。这里是完整的user.html 文件。

<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>User Account</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css">              
</head>
<body>
<div class="container">
	<div class="row">	
		<h1>User Profile</h1>
	</div>
	<br>
	<div class="row">	
		Logged in : <strong>{{session.name}} | <a href="{{ url_for('logout') }}"> Logout</a>
	</div>
	<br><br>
	<div class="row">
	    
		<h2>Welcome to the user profile page...</h2> 
	</div>		
</div>
</body>
</html>

我们将在app.py 中创建函数logout() 来实现注销功能。

@app.route('/logout')
def logout():
    session.pop('loggedin', None)
    session.pop('userid', None)
    session.pop('email', None)
    return redirect(url_for('login'))

我们将在app.py 中创建函数register() ，实现注册功能。

@app.route('/register', methods =['GET', 'POST'])
def register():
    mesage = ''
    if request.method == 'POST' and 'name' in request.form and 'password' in request.form and 'email' in request.form :
        userName = request.form['name']
        password = request.form['password']
        email = request.form['email']
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM user WHERE email = % s', (email, ))
        account = cursor.fetchone()
        if account:
            mesage = 'Account already exists !'
        elif not re.match(r'[^@]+@[^@]+\.[^@]+', email):
            mesage = 'Invalid email address !'
        elif not userName or not password or not email:
            mesage = 'Please fill out the form !'
        else:
            cursor.execute('INSERT INTO user VALUES (NULL, % s, % s, % s)', (userName, email, password, ))
            mysql.connection.commit()
            mesage = 'You have successfully registered !'
    elif request.method == 'POST':
        mesage = 'Please fill out the form !'
    return render_template('register.html', mesage = mesage)

我们将在templates 目录下创建register.html 模板文件，并创建注册表格。

这里是完整的register.html 文件。

<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>User Registeration Form</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css">              
</head>
<body>
<div class="container">
	<h2>User Registration</h2>
	<form action="{{ url_for('register') }}" method="post">
        {% if mesage is defined and mesage %}
			<div class="alert alert-warning">{{ mesage }}</div>
		{% endif %}
		<div class="form-group">
			<label for="name">Name:</label>
			<input type="text" class="form-control" id="name" name="name" placeholder="Enter name" name="name">
		</div>
		<div class="form-group">
			<label for="email">Email:</label>
			<input type="email" class="form-control" id="email" name="email" placeholder="Enter email" name="email">
		</div>
		<div class="form-group">
			<label for="pwd">Password:</label>
			<input type="password" class="form-control" id="password" name="password" placeholder="Enter password" name="pswd">
		</div>    
		<button type="submit" class="btn btn-primary">Register</button>
		<p class="bottom">Already have an account?  <a class="bottom" href="{{url_for('login')}}"> Login here</a></p>
	</form>
</div>        
</body>
</html>

这里是完整的代码，从app.py ，实现登录、注销和注册功能。

from flask import Flask, render_template, request, redirect, url_for, session
from flask_mysqldb import MySQL
import MySQLdb.cursors
import re
  
  
app = Flask(__name__)
  
  
app.secret_key = 'xyzsdfg'
  
app.config['MYSQL_HOST'] = 'localhost'
app.config['MYSQL_USER'] = 'root'
app.config['MYSQL_PASSWORD'] = ''
app.config['MYSQL_DB'] = 'user-system'
  
mysql = MySQL(app)
  
@app.route('/')
@app.route('/login', methods =['GET', 'POST'])
def login():
    mesage = ''
    if request.method == 'POST' and 'email' in request.form and 'password' in request.form:
        email = request.form['email']
        password = request.form['password']
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM user WHERE email = % s AND password = % s', (email, password, ))
        user = cursor.fetchone()
        if user:
            session['loggedin'] = True
            session['userid'] = user['userid']
            session['name'] = user['name']
            session['email'] = user['email']
            mesage = 'Logged in successfully !'
            return render_template('user.html', mesage = mesage)
        else:
            mesage = 'Please enter correct email / password !'
    return render_template('login.html', mesage = mesage)
  
@app.route('/logout')
def logout():
    session.pop('loggedin', None)
    session.pop('userid', None)
    session.pop('email', None)
    return redirect(url_for('login'))
  
@app.route('/register', methods =['GET', 'POST'])
def register():
    mesage = ''
    if request.method == 'POST' and 'name' in request.form and 'password' in request.form and 'email' in request.form :
        userName = request.form['name']
        password = request.form['password']
        email = request.form['email']
        cursor = mysql.connection.cursor(MySQLdb.cursors.DictCursor)
        cursor.execute('SELECT * FROM user WHERE email = % s', (email, ))
        account = cursor.fetchone()
        if account:
            mesage = 'Account already exists !'
        elif not re.match(r'[^@]+@[^@]+\.[^@]+', email):
            mesage = 'Invalid email address !'
        elif not userName or not password or not email:
            mesage = 'Please fill out the form !'
        else:
            cursor.execute('INSERT INTO user VALUES (NULL, % s, % s, % s)', (userName, email, password, ))
            mysql.connection.commit()
            mesage = 'You have successfully registered !'
    elif request.method == 'POST':
        mesage = 'Please fill out the form !'
    return render_template('register.html', mesage = mesage)
    
if __name__ == "__main__":
    app.run()
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