路由与视图¶

from flask import Flask, render_template

app = Flask(__name__)

# 基本路由
@app.route('/')
def index():
    return '首页'

@app.route('/hello')
def hello():
    return '你好，世界！'

# 带参数的路由
@app.route('/user/<username>')
def show_user_profile(username):
    return f'用户: {username}'

# 带类型限制的路由
@app.route('/post/<int:post_id>')
def show_post(post_id):
    return f'文章ID: {post_id}'

@app.route('/path/<path:subpath>')
def show_subpath(subpath):
    return f'子路径: {subpath}'

# 带浮点数的路由
@app.route('/price/<float:price>')
def show_price(price):
    return f'价格: ¥{price:.2f}'

# Flask内置的转换器
converters = {
    'string': '默认类型，接受任何不包含斜杠的文本',
    'int': '接受正整数',
    'float': '接受正浮点数',
    'path': '类似string，但接受斜杠',
    'uuid': '接受UUID字符串'
}

# 自定义转换器
from werkzeug.routing import BaseConverter

class ListConverter(BaseConverter):
    """自定义列表转换器"""
    def to_python(self, value):
        return value.split(',')

    def to_url(self, values):
        return ','.join(super().to_url(value) for value in values)  # super()调用父类方法

# 注册自定义转换器
app.url_map.converters['list'] = ListConverter

# 使用自定义转换器
@app.route('/tags/<list:tags>')
def show_tags(tags):
    return f'标签: {", ".join(tags)}'

from flask import request

# 指定允许的HTTP方法
@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        return '处理登录请求'
    return '显示登录表单'

# RESTful风格的路由
@app.route('/api/users', methods=['GET', 'POST'])
def users():
    if request.method == 'GET':
        return '获取用户列表'
    elif request.method == 'POST':
        return '创建新用户'

@app.route('/api/users/<int:user_id>', methods=['GET', 'PUT', 'DELETE'])
def user_detail(user_id):
    if request.method == 'GET':
        return f'获取用户 {user_id}'
    elif request.method == 'PUT':
        return f'更新用户 {user_id}'
    elif request.method == 'DELETE':
        return f'删除用户 {user_id}'

from flask import jsonify

# GET - 获取资源
@app.route('/api/products', methods=['GET'])
def get_products():
    products = [
        {'id': 1, 'name': '产品A', 'price': 100},
        {'id': 2, 'name': '产品B', 'price': 200}
    ]
    return jsonify(products)

# POST - 创建资源
@app.route('/api/products', methods=['POST'])
def create_product():
    data = request.get_json()
    # 创建产品的逻辑
    return jsonify({'message': '产品创建成功', 'product': data}), 201

# PUT - 更新资源
@app.route('/api/products/<int:product_id>', methods=['PUT'])
def update_product(product_id):
    data = request.get_json()
    # 更新产品的逻辑
    return jsonify({'message': f'产品 {product_id} 更新成功'})

# DELETE - 删除资源
@app.route('/api/products/<int:product_id>', methods=['DELETE'])
def delete_product(product_id):
    # 删除产品的逻辑
    return jsonify({'message': f'产品 {product_id} 删除成功'})

from flask import request

@app.route('/request-info')
def request_info():
    # 获取请求方法
    method = request.method

    # 获取URL参数
    name = request.args.get('name', '默认值')

    # 获取表单数据
    username = request.form.get('username')
    password = request.form.get('password')

    # 获取JSON数据
    data = request.get_json()

    # 获取请求头
    user_agent = request.headers.get('User-Agent')

    # 获取客户端IP
    ip = request.remote_addr

    # 获取上传的文件
    file = request.files.get('file')

    return {
        'method': method,
        'name': name,
        'username': username,
        'data': data,
        'user_agent': user_agent,
        'ip': ip
    }

import os
from werkzeug.utils import secure_filename

# 配置上传目录
UPLOAD_FOLDER = 'uploads'
ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'}
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

def allowed_file(filename):
    """检查文件扩展名是否允许"""
    return '.' in filename and \
           filename.rsplit('.', 1)[1].lower() in ALLOWED_EXTENSIONS

@app.route('/upload', methods=['GET', 'POST'])
def upload_file():
    if request.method == 'POST':
        # 检查是否有文件
        if 'file' not in request.files:
            return '没有文件', 400

        file = request.files['file']

        # 检查文件名是否为空
        if file.filename == '':
            return '没有选择文件', 400

        # 检查文件类型
        if file and allowed_file(file.filename):
            # 安全的文件名
            filename = secure_filename(file.filename)

            # 保存文件
            file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))

            return f'文件 {filename} 上传成功'

    return '''
    <!doctype html>
    <html>
    <head><title>上传文件</title></head>
    <body>
        <h1>上传文件</h1>
        <form method=post enctype=multipart/form-data>
            <input type=file name=file>
            <input type=submit value=上传>
        </form>
    </body>
    </html>
    '''

from flask import abort

@app.route('/user/<int:user_id>')
def get_user(user_id):
    # 验证用户ID
    if user_id <= 0:
        abort(400, description='无效的用户ID')

    # 查询用户
    user = db.session.get(User, user_id)

    if not user:
        abort(404, description='用户不存在')

    return jsonify(user.to_dict())

# 错误处理
@app.errorhandler(400)
def bad_request(error):
    return jsonify({'error': error.description}), 400

@app.errorhandler(404)
def not_found(error):
    return jsonify({'error': error.description}), 404

@app.errorhandler(500)
def internal_error(error):
    return jsonify({'error': '服务器内部错误'}), 500

from flask import Response, make_response, redirect, url_for

# 返回字符串
@app.route('/text')
def text_response():
    return '这是一个文本响应'

# 返回HTML
@app.route('/html')
def html_response():
    return '<h1>这是一个HTML响应</h1>'

# 返回JSON
@app.route('/json')
def json_response():
    data = {'message': 'Hello', 'status': 'success'}
    return jsonify(data)

# 返回元组（响应体，状态码，响应头）
@app.route('/tuple')
def tuple_response():
    return '响应内容', 201, {'X-Custom-Header': 'Custom Value'}

# 使用make_response
@app.route('/make-response')
def make_response_example():
    resp = make_response('自定义响应')
    resp.status_code = 200
    resp.headers['X-Custom'] = 'Value'
    return resp

# 重定向
@app.route('/redirect')
def redirect_example():
    return redirect(url_for('index'))

# 返回Response对象
@app.route('/response')
def response_example():
    resp = Response('自定义响应内容', mimetype='text/plain')
    return resp

from flask import render_template, render_template_string

# 渲染模板
@app.route('/')
def index():
    return render_template('index.html', title='首页')

# 传递变量到模板
@app.route('/user/<username>')
def user_profile(username):
    user = {
        'name': username,
        'email': f'{username}@example.com',
        'age': 25
    }
    return render_template('user.html', user=user)

# 渲染模板字符串
@app.route('/inline')
def inline_template():
    template = '''
    <!DOCTYPE html>
    <html>
    <head><title>{{ title }}</title></head>
    <body>
        <h1>{{ title }}</h1>
        <p>{{ content }}</p>
    </body>
    </html>
    '''
    return render_template_string(template, title='内联模板', content='这是内联渲染的内容')

from flask import make_response

# 设置Cookie
@app.route('/set-cookie')
def set_cookie():
    resp = make_response('Cookie已设置')
    resp.set_cookie('username', '张三', max_age=3600)
    resp.set_cookie('user_id', '12345', max_age=3600)
    return resp

# 读取Cookie
@app.route('/get-cookie')
def get_cookie():
    username = request.cookies.get('username')
    user_id = request.cookies.get('user_id')
    return f'用户名: {username}, 用户ID: {user_id}'

# 删除Cookie
@app.route('/delete-cookie')
def delete_cookie():
    resp = make_response('Cookie已删除')
    resp.delete_cookie('username')
    resp.delete_cookie('user_id')
    return resp

# 安全的Cookie（需要设置SECRET_KEY）
@app.route('/set-secure-cookie')
def set_secure_cookie():
    resp = make_response('安全Cookie已设置')
    resp.set_cookie('session_id', 'abc123',
                   secure=True,  # 仅HTTPS
                   httponly=True,  # 禁止JavaScript访问
                   samesite='Lax')  # 防止CSRF
    return resp

from flask import session
from functools import wraps

# 设置SECRET_KEY
app.secret_key = 'your-secret-key-here'

# 设置Session
@app.route('/login', methods=['POST'])
def login():
    username = request.form.get('username')
    password = request.form.get('password')

    # 验证用户
    if authenticate(username, password):
        session['user_id'] = user.id
        session['username'] = username
        return '登录成功'

    return '登录失败'

# 读取Session
@app.route('/profile')
def profile():
    if 'user_id' in session:
        user_id = session['user_id']
        username = session.get('username')
        return f'用户ID: {user_id}, 用户名: {username}'
    return '请先登录'

# 删除Session
@app.route('/logout')
def logout():
    session.clear()
    return '已登出'

# 检查用户是否登录
def login_required(f):
    """登录验证装饰器"""
    @wraps(f)
    def decorated_function(*args, **kwargs):  # *args接收任意位置参数；**kwargs接收任意关键字参数
        if 'user_id' not in session:
            return redirect(url_for('login'))
        return f(*args, **kwargs)
    return decorated_function

@app.route('/protected')
@login_required
def protected():
    return '这是一个需要登录的页面'

# app/main/__init__.py
from flask import Blueprint

main_bp = Blueprint('main', __name__)

from app.main import routes

# app/main/routes.py
from flask import render_template, Blueprint
from app.main import main_bp

@main_bp.route('/')
def index():
    return render_template('index.html')

@main_bp.route('/about')
def about():
    return render_template('about.html')

# app/auth/__init__.py
from flask import Blueprint

auth_bp = Blueprint('auth', __name__, url_prefix='/auth')

from app.auth import routes

# app/auth/routes.py
from flask import render_template, Blueprint
from app.auth import auth_bp

@auth_bp.route('/login')
def login():
    return render_template('auth/login.html')

@auth_bp.route('/register')
def register():
    return render_template('auth/register.html')

# app/__init__.py
from flask import Flask

def create_app():
    app = Flask(__name__)

    # 注册蓝图
    from app.main import bp as main_bp
    app.register_blueprint(main_bp)

    from app.auth import bp as auth_bp
    app.register_blueprint(auth_bp, url_prefix='/auth')

    return app

# 推荐的路由组织方式
route_organization = {
    '使用蓝图': '将相关路由组织到蓝图中',
    'RESTful设计': '遵循RESTful API设计原则',
    '命名规范': '使用有意义的路由名称',
    '版本控制': 'API使用版本号',
    '文档化': '为API编写文档'
}

# 统一错误处理
@app.errorhandler(Exception)
def handle_exception(e):
    """处理所有未捕获的异常"""
    if isinstance(e, HTTPException):  # isinstance检查对象类型
        return jsonify({'error': e.description}), e.code

    # 记录错误日志
    app.logger.error(f'未处理的异常: {str(e)}')

    return jsonify({'error': '服务器内部错误'}), 500

# 自定义异常
class ValidationError(Exception):
    """验证错误"""
    pass

@app.errorhandler(ValidationError)
def handle_validation_error(e):
    return jsonify({'error': str(e)}), 400