flask

from flask import Flask    //导入flask类

app = Flask(__name__)     

//创建实例‘app’，__name__是特殊变量，直接执行是__main__，被导入时模块名

//用来Flask是构造函数，传递这个变量是为了让Flask应用能找到这个文件

@app.route('/')       //装饰器，里面那个是url,'/'就是指网页根目录，该目录下加载该文件

def hello_world():

    return 'Hello, World!'

if __name__ == '__main__':     //在不是被导入的情况下执行debug

    app.run(debug=True)       //run方法，启动内置的开发服务器，参数表示同时启动调试

@app.route('/')

//需要导入request类

@app.route('/greet/<name>')

def greet(name):

    return f'Hello, {name}!'

//需要导入request类

@app.route('/submit', methods=['POST'])

def submit():

    username = request.form.get('username') //获取POST请求的对应字段

    return f'Hello, {username}!'

//需要导入make_response类

@app.route('/custom_response')

def custom_response():

    response = make_response('This is a custom response!') //创建自定义响应对象

    response.headers['X-Custom-Header'] = 'Value' //创建响应头

    return response

//需要导入render_template类

@app.route('/hello/<name>')

def hello(name):

    return render_template('hello.html', name=name)

//后面那个是传递给模板的变量，注意模板要在templates文件夹中

from flask import Flask

def create_app(config_name):

    app = Flask(__name__)

    app.config.from_object(config_name)    //这个方法从指定对象加载配置

    from . import routes     //从当前包中导入模块routes.py

    app.register_blueprint(routes.bp)   //把其中的蓝图注册到该应用，模块化开发用

    return app

//上面的config_name

class Config:

    DEBUG = True

    SECRET_KEY = 'mysecretkey'  //密钥，加密会话用

    SQLALCHEMY_DATABASE_URI = 'sqlite:///mydatabase.db'  //数据库url

    STATIC_FOLDER = 'static'     //静态文件存储路径

	TEMPLATE_FOLDER = 'templates'    //蓝图存储路径

//这些玩意儿可以Flask(__name__,xxx)来指定。

//需要导入Blueprint

bp = Blueprint('main', __name__)  //蓝图名+当前模块名

@bp.route('/')

def home():

    return 'Home Page'

from flask import Flask

from .routes import bp as main_bp  

//从当前包的 routes.py 模块里导入 bp 对象，并将其重命名为 main_bp。

//包是可以嵌套的..表示父包，可以认为包是一个存储模块的文件夹（所以用.或者..实际上等同于用相对路径）

def create_app():

    app = Flask(__name__)

    app.register_blueprint(main_bp)

    return app

from flask import session

#可以使用 Python 内置的 secrets 模块生成一个强随机性的密钥

#import secrets; print(secrets.token_hex())

app.secret_key = 'your_secret_key_here'

@app.route('/set_session/<username>')

def set_session(username):

    session['username'] = username  //把变量username的值存储在会话中，键为username

    return f'Session set for {username}'

@app.route('/get_session')

def get_session():

    username = session.get('username')  //读取刚刚那个键的值

    return f'Hello, {username}!' if username else 'No session data'

@app.errorhandler(404)

def page_not_found(e):

    return 'Page not found', 404

@app.errorhandler(500)

def internal_server_error(e):

    return 'Internal server error', 500

from flask import Flask, session, redirect, url_for, render_template_string

app = Flask(__name__)

app.secret_key = 'your_secret_key'

@app.route('/')    //定义首页路由

def index():        

    username = session.get('username')

    if username:

        return f'Hello, {username}!'

    else:

        return 'You are not logged in.'

@app.route('/login/<username>')   //定义登录路由

def login(username):

    session['username'] = username

    return redirect(url_for('index'))

@app.route('/logout')    //定义注销路由

def logout():

    session.pop('username', None)   //移除username键

    return redirect(url_for('index'))   //重定向回首页

if __name__ == '__main__':

    app.run(debug=True)

from app import create_app

app = create_app()

if __name__ == '__main__':

  app.run(debug=True)

from flask import Blueprint

bp = Blueprint('main', __name__)

@bp.route('/')

def home():

    return 'Hello, World!'

from flask import Flask

def create_app():

    app = Flask(__name__)

    app.config.from_object('config.Config')

    from . import routes

    app.register_blueprint(routes.bp)

    return app

@app.route('/greet/<name>')   

//这样可以将这一部分当做参数传给函数，比如：

def greet(name):

    return f'Hello, {name}!'

@app.route('/user/<int:user_id>')   //这样就不会全部都当作内容

def user_profile(user_id):

    return f'User ID: {user_id}'

@app.route('/files/<path:filename>')

def serve_file(filename):

    return f'Serving file: {filename}'

@app.route('/submit', methods=['POST'])

@app.route('/items/<int:item_id>/details')

@app.route('/greet/<name>')    #url

@app.route('/submit', methods=['POST'])   #POST

def submit():

    username = request.form.get('username')

    return f'Form submitted by {username}!'

@app.route('/search')   #GET

def search():

    query = request.args.get('query')   //获取 GET 请求中的查询参数query

    return f'Search results for: {query}'

return 'This is a simple message.'

return render_template('hello.html', name=name)  //记得导入render_template

def api_data():    //要导入jsonify

    data = {'key': 'value','key2':'value2'}

    return jsonify(data) 

//自动序列化，将 Python 数据类型（如字典、列表、字符串等，但不是全部）转换为 JSON 格式

//会自动设置Content—Type,支持多参数，自动合并为一个json对象

比如：

    return jsonify(

        message="Hello, World!",

        status=200,

        data=[1, 2, 3, 4]

    )

def info():

    user_agent = request.headers.get('User-Agent')  //有点规律，我说命名

    return f'Your user agent is {user_agent}'

def custom_header():

    response = make_response('Response with custom header')

    response.headers['X-Custom-Header'] = 'Value'

    return response

@app.route('/divide/<int:x>/<int:y>')

def divide(x, y):

    try:

        result = x / y

        return f'Result: {result}'

    except ZeroDivisionError:

        return 'Error: Division by zero', 400  //当然，状态码，可自定义

    //可以返回jsonify格式：

    return jsonify({

            'error': 'Division by zero',

            'message': 'The divisor cannot be zero.'

        }), 400

结构化响应：

def error_response(message, status_code):

    return jsonify({

        'error': {

            'message': message,

            'status_code': status_code

        }

    }), status_code

使用时：

return error_response('Invalid email format', 400, 'INVALID_EMAIL')

全局错误处理：

@app.errorhandler(404)  //定义处理404的函数

def not_found(error):

    return 'Page not found', 404

return 'Everything is OK', 200

return Response('An error occurred', status=500)

return render_template('index.html', title='Welcome Page', name='John Doe') //可以传入对象

@app.template_filter('reverse')

def reverse_filter(s):

    return s[::-1]

<!-- 模板中使用 -->

<!--swig18--> → "olleh"

from flask import Flask, request, redirect, url_for

app = Flask(__name__)

app.secret_key = 'your_secret_key'

@app.route('/upload', methods=['POST'])

def upload():

    file = request.files.get('file')  

    if file:

        filename = file.filename  //获取原始文件名

        file.save(f'uploads/{filename}')

        return f'File uploaded successfully: {filename}'

    return 'No file uploaded'

if __name__ == '__main__':

    app.run(debug=True)