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# Flask + SQLite 简单案例
下面是一个使用Flask和SQLite的完整案例，实现一个简单的用户管理后台系统。
## 项目结构
```
flask_sqlite_demo/
├── app.py # 主应用文件
├── models.py # 数据库模型
├── templates/ # 模板文件夹
│ ├── base.html # 基础模板
│ ├── index.html # 首页
│ ├── add_user.html # 添加用户页面
│ └── edit_user.html # 编辑用户页面
└── instance/ # 实例文件夹(SQLite数据库将创建在这里)
└── app.db # SQLite数据库文件
```
## 代码实现
### 1. app.py
```python
from flask import Flask, render_template, request, redirect, url_for, flash
from models import db, User
app = Flask(__name__)
app.config['SECRET_KEY'] = 'your-secret-key'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///app.db'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
# 初始化数据库
db.init_app(app)
# 创建数据库表
@app.before_first_request
def create_tables():
db.create_all()
@app.route('/')
def index():
users = User.query.all()
return render_template('index.html', users=users)
@app.route('/add', methods=['GET', 'POST'])
def add_user():
if request.method == 'POST':
username = request.form['username']
email = request.form['email']
# 检查用户名是否已存在
if User.query.filter_by(username=username).first():
flash('用户名已存在!', 'error')
return redirect(url_for('add_user'))
# 创建新用户
new_user = User(username=username, email=email)
db.session.add(new_user)
db.session.commit()
flash('用户添加成功!', 'success')
return redirect(url_for('index'))
return render_template('add_user.html')
@app.route('/edit/<int:user_id>', methods=['GET', 'POST'])
def edit_user(user_id):
user = User.query.get_or_404(user_id)
if request.method == 'POST':
user.username = request.form['username']
user.email = request.form['email']
db.session.commit()
flash('用户信息更新成功!', 'success')
return redirect(url_for('index'))
return render_template('edit_user.html', user=user)
@app.route('/delete/<int:user_id>')
def delete_user(user_id):
user = User.query.get_or_404(user_id)
db.session.delete(user)
db.session.commit()
flash('用户删除成功!', 'success')
return redirect(url_for('index'))
if __name__ == '__main__':
app.run(debug=True)
```
### 2. models.py
```python
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()
class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True, nullable=False)
email = db.Column(db.String(120), unique=True, nullable=False)
def __repr__(self):
return f'<User {self.username}>'
```
### 3. templates/base.html
```html
<!DOCTYPE html>
<html>
<head>
<title>Flask SQLite Demo</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
</head>
<body>
<div class="container mt-4">
{% with messages = get_flashed_messages(with_categories=true) %}
{% if messages %}
{% for category, message in messages %}
<div class="alert alert-{{ category }}">{{ message }}</div>
{% endfor %}
{% endif %}
{% endwith %}
{% block content %}{% endblock %}
</div>
</body>
</html>
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