Flask从入门到精通
Flask
0.Flask简介
Flask是一个基于Python开发并且依赖jinja2模板和Werkzeug WSGI服务的一个微型框架,对于Werkzeug本质是Socket服务端,其用于接收http请求并对请求进行预处理,然后触发Flask框架,开发人员基于Flask框架提供的功能对请求进行相应的处理,并返回给用户,如果要返回给用户复杂的内容时,需要借助jinja2模板来实现对模板的处理,即:将模板和数据进行渲染,将渲染后的字符串返回给用户浏览器。
“微”(micro) 并不表示你需要把整个 Web 应用塞进单个 Python 文件(虽然确实可以 ),也不意味着 Flask 在功能上有所欠缺。微框架中的“微”意味着 Flask 旨在保持核心简单而易于扩展。Flask 不会替你做出太多决策——比如使用何种数据库。而那些 Flask 所选择的——比如使用何种模板引擎——则很容易替换。除此之外的一切都由可由你掌握。如此,Flask 可以与您珠联璧合。
默认情况下,Flask 不包含数据库抽象层、表单验证,或是其它任何已有多种库可以胜任的功能。然而,Flask 支持用扩展来给应用添加这些功能,如同是 Flask 本身实现的一样。众多的扩展提供了数据库集成、表单验证、上传处理、各种各样的开放认证技术等功能。Flask 也许是“微小”的,但它已准备好在需求繁杂的生产环境中投入使用
wsgiref
最简单的Web应用就是先把HTML用文件保存好,用一个现成的HTTP服务器软件,接收用户请求,从文件中读取HTML,返回。
如果要动态生成HTML,就需要把上述步骤自己来实现。不过,接受HTTP请求、解析HTTP请求、发送HTTP响应都是苦力活,如果我们自己来写这些底层代码,还没开始写动态HTML呢,就得花个把月去读HTTP规范。
正确的做法是底层代码由专门的服务器软件实现,我们用Python专注于生成HTML文档。因为我们不希望接触到TCP连接、HTTP原始请求和响应格式,所以,需要一个统一的接口协议来实现这样的服务器软件,让我们专心用Python编写Web业务。这个接口就是WSGI:Web Server Gateway Interface。而wsgiref模块就是python基于wsgi协议开发的服务模块
from wsgiref.simple_server import make_serverdef mya(environ, start_response):print(environ)start_response('200 OK', [('Content-Type', 'text/html')])if environ.get('PATH_INFO') == '/index':with open('index.html','rb') as f:data=f.read()elif environ.get('PATH_INFO') == '/login':with open('login.html', 'rb') as f:data = f.read()else:data=b'<h1>Hello, web!</h1>'return [data]if __name__ == '__main__':myserver = make_server('', 8011, mya)print('监听8010')myserver.serve_forever()wsgiref简单应用
1.安装
pip3 install flask
2.werkzeug简介
Werkzeug是一个WSGI工具包,他可以作为一个Web框架的底层库。这里稍微说一下, werkzeug 不是一个web服务器,也不是一个web框架,而是一个工具包,官方的介绍说是一个 WSGI 工具包,它可以作为一个 Web 框架的底层库,因为它封装好了很多 Web 框架的东西,例如 Request,Response 等等
代码示例:
from werkzeug.wrappers import Request, Response@Request.application
def hello(request):return Response('Hello World!')if __name__ == '__main__':from werkzeug.serving import run_simplerun_simple('localhost', 4000, hello)
3.flask快速使用
from flask import Flask
# 实例化产生一个Flask对象
app = Flask(__name__)
# 将 '/'和视图函数hello_workd的对应关系添加到路由中
@app.route('/') # 1. v=app.route('/') 2. v(hello_world)
def hello_world():return 'Hello World!'if __name__ == '__main__':app.run() # 最终调用了run_simple()
案例:登录,显示用户信息
main.py
from flask import Flask, render_template, request, redirect, session, url_forapp = Flask(__name__)
app.debug = True
app.secret_key = 'sdfsdfsdfsdf'USERS = {1: {'name': '刘亦菲', 'age': 18, 'gender': '男', 'text': "刘亦菲,1987年8月25日出生于湖北省武汉市,华语影视女演员、歌手,毕业于北京电影学院2002级表演系本科",'img':'https://img2.woyaogexing.com/2021/10/16/e3ccba623848430ba83209c0621a2256!400x400.jpeg'},2: {'name': '彭于晏', 'age': 28, 'gender': '男', 'text': "彭于晏,1982年3月24日出生于中国台湾省澎湖县,毕业于不列颠哥伦比亚大学,华语影视男演员。。。。。。。。",'img':'https://img2.woyaogexing.com/2021/10/16/e71aa35728c34313bccb4c371192990f!400x400.jpeg'},3: {'name': '迪丽热巴', 'age': 38, 'gender': '女', 'text': "迪丽热巴(Dilraba),1992年6月3日出生于中国新疆乌鲁木齐市,毕业于上海戏剧学院,中国内地影视女演员",'img':'https://img2.woyaogexing.com/2021/10/30/6a34146dde2d4f1c832463a5be1ed027!400x400.jpeg'},4: {'name': '亚瑟', 'age': 38, 'gender': '男', 'text': "亚瑟,是腾讯手游《王者荣耀》中一名战士型英雄角色,也是《王者荣耀》的新手英雄之一,既可攻又可守",'img':'https://img2.woyaogexing.com/2021/10/30/371b2aa7a03c4f53b7b1bc86f877d7d1!400x400.jpeg'},
}@app.route('/detail/<int:nid>', methods=['GET'])
def detail(nid):user = session.get('user_info')if not user:return redirect('/login')info = USERS.get(nid)return render_template('detail.html', info=info)@app.route('/', methods=['GET'])
def index():user = session.get('user_info')if not user:return redirect('/login')# url = url_for('l1')# return redirect(url)return render_template('index.html', user_dict=USERS)@app.route('/login', methods=['GET', 'POST'], endpoint='l1')
def login():if request.method == "GET":return render_template('login.html')else:# request.query_stringusername = request.form.get('username')password = request.form.get('password')if username == 'lqz' and password == '123':session['user_info'] = passwordreturn redirect('/')return render_template('login.html', error='用户名或密码错误')if __name__ == '__main__':app.run()
detail.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/css/bootstrap.min.css"><script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/js/bootstrap.bundle.min.js"></script><title>Title</title>
</head>
<body>
<div class="container"><div class="sticky-top"><header class="d-flex flex-wrap justify-content-center py-3 mb-4 border-bottom"><a href="/" class="d-flex align-items-center mb-3 mb-md-0 me-md-auto text-dark text-decoration-none"><svg class="bi me-2" width="40" height="32"><use xlink:href="#bootstrap"></use></svg><span class="fs-4">交友平台</span></a><ul class="nav nav-pills"><li class="nav-item"><a href="#" class="nav-link active" aria-current="page">首页</a></li><li class="nav-item"><a href="#" class="nav-link">女生</a></li><li class="nav-item"><a href="#" class="nav-link">男生</a></li><li class="nav-item"><a href="#" class="nav-link">国产</a></li><li class="nav-item"><a href="#" class="nav-link">欧美</a></li></ul></header></div><div class="position-relative overflow-hidden p-3 p-md-5 m-md-3 text-center bg-light"><div class="col-md-5 p-lg-5 mx-auto my-5"><h1 class="display-4 fw-normal">{{info.name}}</h1><img src="{{info.img}}" alt=""width="300px" height="300px" style="margin: 20px"><p class="lead fw-normal">{{info.text}}</p><a class="btn btn-outline-secondary" href="#">收藏</a></div><div class="product-device shadow-sm d-none d-md-block"></div><div class="product-device product-device-2 shadow-sm d-none d-md-block"></div></div><div><footer class="py-3 my-4"><ul class="nav justify-content-center border-bottom pb-3 mb-3"><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">首页</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">特性</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">联系我们</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">资料获取</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">关于</a></li></ul><p class="text-center text-muted">Copyright © 1998 - 2029 liuqingzheng. All Rights Reserved. </p></footer></div></div>
</body>
</html>
index.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/css/bootstrap.min.css"><script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/js/bootstrap.bundle.min.js"></script><title>Title</title>
</head>
<body>
<div class="container"><!-- 头部--><div class="sticky-top"><header class="d-flex flex-wrap justify-content-center py-3 mb-4 border-bottom"><a href="/" class="d-flex align-items-center mb-3 mb-md-0 me-md-auto text-dark text-decoration-none"><svg class="bi me-2" width="40" height="32"><use xlink:href="#bootstrap"></use></svg><span class="fs-4">交友平台</span></a><ul class="nav nav-pills"><li class="nav-item"><a href="#" class="nav-link active" aria-current="page">首页</a></li><li class="nav-item"><a href="#" class="nav-link">女生</a></li><li class="nav-item"><a href="#" class="nav-link">男生</a></li><li class="nav-item"><a href="#" class="nav-link">国产</a></li><li class="nav-item"><a href="#" class="nav-link">欧美</a></li></ul></header></div><!--轮播图--><div><div class="bd-example-snippet bd-code-snippet"><div class="bd-example"><div id="carouselExampleCaptions" class="carousel slide" data-bs-ride="carousel"><div class="carousel-indicators"><button type="button" data-bs-target="#carouselExampleCaptions" data-bs-slide-to="0" class=""aria-label="Slide 1"></button><button type="button" data-bs-target="#carouselExampleCaptions" data-bs-slide-to="1"aria-label="Slide 2" class="active" aria-current="true"></button><button type="button" data-bs-target="#carouselExampleCaptions" data-bs-slide-to="2"aria-label="Slide 3" class=""></button></div><div class="carousel-inner"><div class="carousel-item"><img src="https://img.zcool.cn/community/01fb5458fedf57a801214550f9677a.jpg@2o.jpg" alt=""width="100%" height="300"><div class="carousel-caption d-none d-md-block"><h5>激情绿荫</h5><p>Some representative placeholder content for the first slide.</p></div></div><div class="carousel-item active"><img src="https://img2.baidu.com/it/u=2951612437,4135887500&fm=253&fmt=auto&app=138&f=JPEG"alt="" width="100%" height="300"><div class="carousel-caption d-none d-md-block"><h5>品牌雨伞</h5><p>Some representative placeholder content for the second slide.</p></div></div><div class="carousel-item"><img src="https://img1.baidu.com/it/u=1417689082,3333220267&fm=253&fmt=auto&app=138&f=JPEG"alt="" width="100%" height="300"><div class="carousel-caption d-none d-md-block"><h5>家装节</h5><p>Some representative placeholder content for the third slide.</p></div></div></div><button class="carousel-control-prev" type="button" data-bs-target="#carouselExampleCaptions"data-bs-slide="prev"><span class="carousel-control-prev-icon" aria-hidden="true"></span><span class="visually-hidden">Previous</span></button><button class="carousel-control-next" type="button" data-bs-target="#carouselExampleCaptions"data-bs-slide="next"><span class="carousel-control-next-icon" aria-hidden="true"></span><span class="visually-hidden">Next</span></button></div></div></div></div><!-- 内容--><div class="row row-cols-md-2" style="padding: 10px">{% for k,v in user_dict.items() %}<div class="card"><div class="row " style="padding: 10px"><img src="{{v.get('img')}}" alt="" class="col-md-4"><div class="col-md-8"><div class="card-body"><h5 class="card-title">{{v['name']}}</h5><p class="card-text">{{v.text}}</p><p class="card-text"><a href="/detail/{{k}}" class="btn btn-danger">查看详细</a></p></div></div></div></div>{%endfor%}</div><!-- table--><div class="bd-example" style="margin-top: 30px"><table class="table table-hover table-striped table-bordered"><thead><tr class="table-danger"><th colspan="3" class="text-center">更多交友</th></tr></thead><tbody><tr class="table-success"><th>杨幂</th><td>女</td><td>33</td></tr><tr class="table-warning"><th scope="row">刘亦菲</th><td>未知</td><td>40</td></tr><tr class="table-success"><th scope="row">彭于晏</th><td>男</td><td>23</td></tr><tr class="table-warning"><th scope="row">陈奕迅</th><td>男</td><td>44</td></tr><tr class="table-success"><th scope="row">薛之谦</th><td>男</td><td>36</td></tr><tr class="table-warning"><th>李清照</th><td>女</td><td>未知</td></tr></tbody></table></div><!--分页--><div class="d-flex justify-content-center"><ul class="pagination pagination-lg"><li class="page-item"><a class="page-link" href="#" aria-label="Previous"><span aria-hidden="true">«</span></a></li><li class="page-item"><a class="page-link" href="#">1</a></li><li class="page-item"><a class="page-link" href="#">2</a></li><li class="page-item"><a class="page-link" href="#">3</a></li><li class="page-item"><a class="page-link" href="#">4</a></li><li class="page-item"><a class="page-link" href="#">5</a></li><li class="page-item"><a class="page-link" href="#">6</a></li><li class="page-item"><a class="page-link" href="#" aria-label="Next"><span aria-hidden="true">»</span></a></li></ul></div><!-- 尾部--><div><footer class="py-3 my-4"><ul class="nav justify-content-center border-bottom pb-3 mb-3"><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">首页</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">特性</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">联系我们</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">资料获取</a></li><li class="nav-item"><a href="#" class="nav-link px-2 text-muted">关于</a></li></ul><p class="text-center text-muted">Copyright © 1998 - 2029 liuqingzheng. All Rights Reserved. </p></footer></div>
</div>
</body>
</html>
login.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/css/bootstrap.min.css"><title>登录</title>
</head>
<body>
<div class="container col-xl-10 col-xxl-8 px-4 py-5"><div class="row align-items-center g-lg-5 py-5"><div class="col-lg-7 text-center text-lg-start"><h1 class="display-4 fw-bold lh-1 mb-3">亚洲最大交友平台</h1><p class="col-lg-10 fs-4">Bootstrap是Twitter推出的一个用于前端开发的开源工具包。它由Twitter的设计师MarkOtto和Jacob Thornton合作开发,是一个CSS/HTML框架。目前,Bootstrap最新版本为5.0</p></div><div class="col-md-10 mx-auto col-lg-5"><form class="p-4 p-md-5 border rounded-3 bg-light" method="post"><div class="form-floating mb-3"><input type="text" class="form-control" id="floatingInput" placeholder="name@example.com" name="username"><label for="floatingInput">用户名</label></div><div class="form-floating mb-3"><input type="password" class="form-control" id="floatingPassword" placeholder="Password" name="password"><label for="floatingPassword">密码</label></div><div class="checkbox mb-3"><label><input type="checkbox" value="remember-me"> 记住密码</label></div><button class="w-100 btn btn-lg btn-primary" type="submit">登录</button><hr class="my-4"><small class="text-muted">{{error}}</small></form></div></div>
</div>
</body>
</html>
4.配置文件
flask中的配置文件是一个flask.config.Config对象(继承字典),默认配置为:{'DEBUG': get_debug_flag(default=False), 是否开启Debug模式'TESTING': False, 是否开启测试模式'PROPAGATE_EXCEPTIONS': None, 'PRESERVE_CONTEXT_ON_EXCEPTION': None,'SECRET_KEY': None,'PERMANENT_SESSION_LIFETIME': timedelta(days=31),'USE_X_SENDFILE': False,'LOGGER_NAME': None,'LOGGER_HANDLER_POLICY': 'always','SERVER_NAME': None,'APPLICATION_ROOT': None,'SESSION_COOKIE_NAME': 'session','SESSION_COOKIE_DOMAIN': None,'SESSION_COOKIE_PATH': None,'SESSION_COOKIE_HTTPONLY': True,'SESSION_COOKIE_SECURE': False,'SESSION_REFRESH_EACH_REQUEST': True,'MAX_CONTENT_LENGTH': None,'SEND_FILE_MAX_AGE_DEFAULT': timedelta(hours=12),'TRAP_BAD_REQUEST_ERRORS': False,'TRAP_HTTP_EXCEPTIONS': False,'EXPLAIN_TEMPLATE_LOADING': False,'PREFERRED_URL_SCHEME': 'http','JSON_AS_ASCII': True,'JSON_SORT_KEYS': True,'JSONIFY_PRETTYPRINT_REGULAR': True,'JSONIFY_MIMETYPE': 'application/json','TEMPLATES_AUTO_RELOAD': None,}
方式一
app.config['DEBUG'] = TruePS: 由于Config对象本质上是字典,所以还可以使用app.config.update(...)
方式二
#通过py文件配置
app.config.from_pyfile("python文件名称")
如:
settings.py
DEBUG = Trueapp.config.from_pyfile("settings.py")
#通过环境变量配置
app.config.from_envvar("环境变量名称")
#app.config.from_pyfile(os.environ['YOURAPPLICATION_SETTINGS'])
环境变量的值为python文件名称名称,内部调用from_pyfile方法app.config.from_json("json文件名称")
JSON文件名称,必须是json格式,因为内部会执行json.loadsapp.config.from_mapping({'DEBUG': True})
字典格式app.config.from_object("python类或类的路径")app.config.from_object('pro_flask.settings.TestingConfig')settings.pyclass Config(object):DEBUG = FalseTESTING = FalseDATABASE_URI = 'sqlite://:memory:'class ProductionConfig(Config):DATABASE_URI = 'mysql://user@localhost/foo'class DevelopmentConfig(Config):DEBUG = Trueclass TestingConfig(Config):TESTING = TruePS: 从sys.path中已经存在路径开始写PS: settings.py文件默认路径要放在程序root_path目录,如果instance_relative_config为True,则就是instance_path目录(Flask对象init方法的参数)
5.路由系统
典型写法
@app.route('/detail/<int:nid>',methods=['GET'],endpoint='detail')
默认转换器
DEFAULT_CONVERTERS = {'default': UnicodeConverter,'string': UnicodeConverter,'any': AnyConverter,'path': PathConverter,'int': IntegerConverter,'float': FloatConverter,'uuid': UUIDConverter,
}
路由系统本质
"""
1. decorator = app.route('/',methods=['GET','POST'],endpoint='n1')def route(self, rule, **options):# app对象# rule= /# options = {methods=['GET','POST'],endpoint='n1'}def decorator(f):endpoint = options.pop('endpoint', None)self.add_url_rule(rule, endpoint, f, **options)return freturn decorator
2. @decoratordecorator(index)
"""
#同理
def login():return '登录'
app.add_url_rule('/login', 'n2', login, methods=['GET',"POST"])
#与django路由类似
#django与flask路由:flask路由基于装饰器,本质是基于:add_url_rule
#add_url_rule 源码中,endpoint如果为空,endpoint = _endpoint_from_view_func(view_func),最终取view_func.__name__(函数名)
CBV(源码分析)
def auth(func):def inner(*args, **kwargs):print('before')result = func(*args, **kwargs)print('after')return resultreturn innerclass IndexView(views.View):methods = ['GET']decorators = [auth, ]def dispatch_request(self):print('Index')return 'Index!'app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint
#或者,通常用此方式class IndexView(views.MethodView):methods = ['GET']decorators = [auth, ]def get(self):return 'Index.GET'def post(self):return 'Index.POST'app.add_url_rule('/index', view_func=IndexView.as_view(name='index')) # name=endpoint
app.add_url_rule参数
@app.route和app.add_url_rule参数:
rule, URL规则
view_func, 视图函数名称
defaults = None, 默认值, 当URL中无参数,函数需要参数时,使用defaults = {'k': 'v'}
为函数提供参数
endpoint = None, 名称,用于反向生成URL,即: url_for('名称')
methods = None, 允许的请求方式,如:["GET", "POST"]
#对URL最后的 / 符号是否严格要求
strict_slashes = None'''@app.route('/index', strict_slashes=False)#访问http://www.xx.com/index/ 或http://www.xx.com/index均可@app.route('/index', strict_slashes=True)#仅访问http://www.xx.com/index'''
#重定向到指定地址
redirect_to = None, '''@app.route('/index/<int:nid>', redirect_to='/home/<nid>')'''#子域名访问
subdomain = None, '''#C:\Windows\System32\drivers\etc\hosts127.0.0.1 www.liuqingzheng.com127.0.0.1 admin.liuqingzheng.com127.0.0.1 buy.liuqingzheng.comfrom flask import Flask, views, url_forapp = Flask(import_name=__name__)app.config['SERVER_NAME'] = 'liuqingzheng.com:5000'@app.route("/", subdomain="admin")def static_index():"""Flask supports static subdomainsThis is available at static.your-domain.tld"""return "static.your-domain.tld"#可以传入任意的字符串,如传入的字符串为aa,显示为 aa.liuqingzheng.com@app.route("/dynamic", subdomain="<username>")def username_index(username):"""Dynamic subdomains are also supportedTry going to user1.your-domain.tld/dynamic"""return username + ".your-domain.tld"if __name__ == '__main__':app.run()访问:http://www.liuqingzheng.com:5000/dynamichttp://admin.liuqingzheng.com:5000/dynamichttp://buy.liuqingzheng.com:5000/dynamic'''
支持正则
#1 写类,继承BaseConverter
#2 注册:app.url_map.converters['regex'] = RegexConverter
# 3 使用:@app.route('/index/<regex("\d+"):nid>') 正则表达式会当作第二个参数传递到类中
from flask import Flask, views, url_for
from werkzeug.routing import BaseConverterapp = Flask(import_name=__name__)class RegexConverter(BaseConverter):"""自定义URL匹配正则表达式"""def __init__(self, map, regex):super(RegexConverter, self).__init__(map)self.regex = regexdef to_python(self, value):"""路由匹配时,匹配成功后传递给视图函数中参数的值"""return int(value)def to_url(self, value):"""使用url_for反向生成URL时,传递的参数经过该方法处理,返回的值用于生成URL中的参数"""val = super(RegexConverter, self).to_url(value)return val
# 添加到flask中
app.url_map.converters['regex'] = RegexConverter
@app.route('/index/<regex("\d+"):nid>')
def index(nid):print(url_for('index', nid='888'))return 'Index'if __name__ == '__main__':app.run()
6.模版
6.1渲染变量
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><h1>用户列表</h1><table>{% for k,v in user_dict.items() %}<tr><td>{{k}}</td><td>{{v.name}}</td><td>{{v['name']}}</td><td>{{v.get('name')}}</td><td><a href="/detail/{{k}}">查看详细</a></td></tr>{% endfor %}</table>
</body>
</html>
6.2变量的循环
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><h1>用户列表</h1><table>{% for k,v in user_dict.items() %}<tr><td>{{k}}</td><td>{{v.name}}</td><td>{{v['name']}}</td><td>{{v.get('name')}}</td><td><a href="/detail/{{k}}">查看详细</a></td></tr>{% endfor %}</table>
</body>
</html>
6.3逻辑判断
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><h1>用户列表</h1><table>{% if name %}<h1>Hello {{ name }}!</h1>{% else %}<h1>Hello World!</h1>{% endif %}</table>
</body>
</html>
比django中多可以加括号,执行函数,传参数
from flask import Flask,render_template,Markup,jsonify,make_response
app = Flask(__name__)def func1(arg):return Markup("<input type='text' value='%s' />" %(arg,))
@app.route('/')
def index():return render_template('index.html',ff = func1)if __name__ == '__main__':app.run()
index.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>{{ff('六五')}}{{ff('六五')|safe}}</body>
</html>
注意:
1.Markup等价django的mark_safe ,
2.extends,include一模一样
7.请求响应
from flask import Flaskfrom flask import requestfrom flask import render_templatefrom flask import redirectfrom flask import make_responseapp = Flask(__name__)@app.route('/login.html', methods=['GET', "POST"])def login():# 请求相关信息# request.method 提交的方法# request.args get请求提及的数据# request.form post请求提交的数据# request.values post和get提交的数据总和# request.cookies 客户端所带的cookie# request.headers 请求头# request.path 不带域名,请求路径# request.full_path 不带域名,带参数的请求路径# request.script_root # request.url 带域名带参数的请求路径# request.base_url 带域名请求路径# request.url_root 域名# request.host_url 域名# request.host 127.0.0.1:500# request.files# obj = request.files['the_file_name']# obj.save('/var/www/uploads/' + secure_filename(f.filename))# 响应相关信息# return "字符串"# return render_template('html模板路径',**{})# return redirect('/index.html')#return jsonify({'k1':'v1'})# response = make_response(render_template('index.html'))# response是flask.wrappers.Response类型# response.delete_cookie('key')# response.set_cookie('key', 'value')# response.headers['X-Something'] = 'A value'# return responsereturn "内容"if __name__ == '__main__':app.run()
8.session
cookie:存放在客户端的键值对
session:存放在客户端的键值对
token:存放在客户端,通过算法来校验
在使用session之前必须现在设置一下密钥
app.secret_key="asdas" #值随便
除请求对象之外,还有一个 session 对象。它允许你在不同请求间存储特定用户的信息。它是在 Cookies 的基础上实现的,并且对 Cookies 进行密钥签名要使用会话,你需要设置一个密钥。 (app.session_interface对象)
设置:session['username'] = 'xxx'
#在django中发什么三件事,1,生成一个随机的字符串 2 往数据库存 3 写入cookie返回浏览器
#在flask中他没有数据库,但session是怎样实现的?# 生成一个密钥写入这个cookie,然后下次请求的时候,通过这个cookie解密,然后赋值给session#我们通过app.session_interface来查看删除:session.pop('username', None)
app.session_interface中save_session的参数(设置cookie的参数)
key, 键
value='', 值
max_age=None, 超时时间 cookie需要延续的时间(以秒为单位)如果参数是\ None`` ,这个cookie会延续到浏览器关闭为止
expires=None, 超时时间(IE requires expires, so set it if hasn't been already.)
path='/', Cookie生效的路径,/ 表示根路径,特殊的:根路径的cookie可以被任何url的页面访问,浏览器只会把cookie回传给带有该路径的页面,这样可以避免将cookie传给站点中的其他的应用。
domain=None, Cookie生效的域名 你可用这个参数来构造一个跨站cookie。如, domain=".example.com"所构造的cookie对下面这些站点都是可读的:www.example.com 、 www2.example.com 和an.other.sub.domain.example.com 。如果该参数设置为 None ,cookie只能由设置它的站点读取
secure=False, 浏览器将通过HTTPS来回传cookie
httponly=False 只能http协议传输,无法被JavaScript获取(不是绝对,底层抓包可以获取到也可以被覆盖)
session源码的执行流程
-save_seesion-响应的时候,把session中的值加密序列化放大到了cookie中,返回到浏览器中
-open_session-请求来了,从cookie中取出值,反解,生成session对象,以后再视图函数中直接用sessoin就可以了。
9.闪现(message)
-设置:flash('aaa')
-取值:get_flashed_message()
-
-假设在a页面操作出错,跳转到b页面,在b页面显示a页面的错误信息
示例:
from flask import Flask,flash,get_flashed_messages,request,redirectapp = Flask(__name__)
app.secret_key = 'asdfasdf'@app.route('/index')
def index():# 从某个地方获取设置过的所有值,并清除。val = request.args.get('v')if val == 'oldboy':return 'Hello World!'flash('超时错误',category="x1")return "ssdsdsdfsd"# return redirect('/error')@app.route('/error')
def error():"""展示错误信息:return:如果get_flashed_messages(with_category=True)"""data = get_flashed_messages(category_filter=['x1'])if data:msg = data[0]else:msg = "..."return "错误信息:%s" %(msg,)if __name__ == '__main__':app.run()
10.请求扩展
1 before_request
类比django中间件中的process_request,在请求收到之前绑定一个函数做一些事情
#基于它做用户登录认证
@app.before_request
def process_request(*args,**kwargs):if request.path == '/login':return Noneuser = session.get('user_info')if user:return Nonereturn redirect('/login')
2 after_request
类比django中间件中的process_response,每一个请求之后绑定一个函数,如果请求没有异常
@app.after_request
def process_response1(response):print('process_response1 走了')return response
3 before_first_request
第一次请求时,跟浏览器无关
@app.before_first_request
def first():pass
4 teardown_request
每一个请求之后绑定一个函数,即使遇到了异常
@app.teardown_request
def ter(e):pass
5 errorhandler
路径不存在时404,服务器内部错误500
@app.errorhandler(404)
def error_404(arg):return "404错误了"
6 template_global
标签
@app.template_global()
def sb(a1, a2):return a1 + a2
#{{sb(1,2)}}
7 template_filter
过滤器
@app.template_filter()
def db(a1, a2, a3):return a1 + a2 + a3
#{{ 1|db(2,3)}}
总结:
1 重点掌握before_request和after_request,
2 注意有多个的情况,执行顺序
3 before_request请求拦截后(也就是有return值),response所有都执行
11 中间件(了解)
from flask import Flaskapp = Flask(__name__)@app.route('/')
def index():return 'Hello World!'
# 模拟中间件
class Md(object):def __init__(self,old_wsgi_app):self.old_wsgi_app = old_wsgi_appdef __call__(self, environ, start_response):print('开始之前')ret = self.old_wsgi_app(environ, start_response)print('结束之后')return retif __name__ == '__main__':#1我们发现当执行app.run方法的时候,最终执行run_simple,最后执行app(),也就是在执行app.__call__方法 #2 在__call__里面,执行的是self.wsgi_app().那我们希望在执行他本身的wsgi之前做点事情。#3 所以我们先用Md类中__init__,保存之前的wsgi,然后我们用将app.wsgi转化成Md的对象。#4 那执行新的的app.wsgi_app,就是执行Md的__call__方法。#把原来的wsgi_app替换为自定义的,app.wsgi_app = Md(app.wsgi_app)app.run()
请求所有的流程
ctx = self.request_context(environ)error = Nonetry:try:ctx.push()#根据路径去执行视图函数,视图类response = self.full_dispatch_request()except Exception as e:error = eresponse = self.handle_exception(e)except: # noqa: B001error = sys.exc_info()[1]raisereturn response(environ, start_response)finally:#不管出不出异常,都会走这里if self.should_ignore_error(error):error = Nonectx.auto_pop(error)
12.蓝图
对程序进行目录结构划分
不使用蓝图,自己分文件
目录结构:
-templates
-views-__init__.py-user.py-order.py
-app.py
app.py
from views import app
if __name__ == '__main__':app.run()
init.py
from flask import Flask,request
app = Flask(__name__)
#不导入这个不行
from . import account
from . import order
from . import user
user.py
from . import app
@app.route('/user')
def user():return 'user'
order.py
from . import app
@app.route('/order')
def order():return 'order'
使用蓝图之中小型系统
详见代码:pro_flask_简单应用程序目录示例.zip
目录结构:
-flask_pro-flask_test-__init__.py-static-templates-views-order.py-user.py-manage.py
_init.py
from flask import Flask
app=Flask(__name__)
from flask_test.views import user
from flask_test.views import order
app.register_blueprint(user.us)
app.register_blueprint(order.ord)
manage.py
from flask_test import app
if __name__ == '__main__':app.run(port=8008)
user.py
from flask import Blueprint
us=Blueprint('user',__name__)@us.route('/login')
def login():return 'login'
order.py
from flask import Blueprint
ord=Blueprint('order',__name__)@ord.route('/test')
def test():return 'order test'
使用蓝图之大型系统
详见代码:pro_flask_大型应用目录示例.zip
总结:
1 xxx = Blueprint('account', name,url_prefix='/xxx') :蓝图URL前缀,表示url的前缀,在该蓝图下所有url都加前缀
2 xxx = Blueprint('account', name,url_prefix='/xxx',template_folder='tpls'):给当前蓝图单独使用templates,向上查找,当前找不到,会找总templates
3 蓝图的befort_request,对当前蓝图有效
4 大型项目,可以模拟出类似于django中app的概念
13.请求上下文源码分析
第一阶段:将ctx(request,session)放到Local对象上第二阶段:视图函数导入:request/session
request.method-LocalProxy对象.method,执行getattr方法,getattr(self._get_current_object(), name)-self._get_current_object()返回return self.__local(),self.__local(),在LocakProxy实例化的时候,object.__setattr__(self, '_LocalProxy__local', local),此处local就是:partial(_lookup_req_object, 'request')-def _lookup_req_object(name):top = _request_ctx_stack.top #_request_ctx_stack 就是LocalStack()对象,top方法把ctx取出来if top is None:raise RuntimeError(_request_ctx_err_msg)return getattr(top, name)#获取ctx中的request或session对象第三阶段:请求处理完毕- 获取session并保存到cookie- 将ctx删除
程序运行,两个LocalStack()对象,一个里面放request和session,另一个放g和current_app
14.g对象
专门用来存储用户信息的g对象,g的全称的为global
g对象在一次请求中的所有的代码的地方,都是可以使用的
g对象和session的区别
session对象是可以跨request的,只要session还未失效,不同的request的请求会获取到同一个session,但是g对象不是,g对象不需要管过期时间,请求一次就g对象就改变了一次,或者重新赋值了一次
15.flask-session
作用:将默认保存的签名cookie中的值 保存到 redis/memcached/file/Mongodb/SQLAlchemy
安装:pip3 install flask-session
使用1:
from flask import Flask,session
from flask_session import RedisSessionInterface
import redis
app = Flask(__name__)
conn=redis.Redis(host='127.0.0.1',port=6379)
#use_signer是否对key签名
app.session_interface=RedisSessionInterface(conn,key_prefix='lqz')
@app.route('/')
def hello_world():session['name']='lqz'return 'Hello World!'if __name__ == '__main__':app.run()
使用2:
from redis import Redis
from flask.ext.session import Session
app.config['SESSION_TYPE'] = 'redis'
app.config['SESSION_REDIS'] = Redis(host='192.168.0.94',port='6379')
Session(app)
问题:设置cookie时,如何设定关闭浏览器则cookie失效。
response.set_cookie('k','v',exipre=None)#这样设置即可
#在session中设置
app.session_interface=RedisSessionInterface(conn,key_prefix='lqz',permanent=False)
#一般不用,我们一般都设置超时时间,多长时间后失效
问题:cookie默认超时时间是多少?如何设置超时时间
#源码expires = self.get_expiration_time(app, session)
'PERMANENT_SESSION_LIFETIME': timedelta(days=31),#这个配置文件控制
16.数据库连接池
pymsql链接数据库
import pymysqlconn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123456', db='s8day127db')
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
# cursor.execute("select id,name from users where name=%s and pwd=%s",['lqz','123',])
cursor.execute("select id,name from users where name=%(user)s and pwd=%(pwd)s",{'user':'lqz','pwd':'123'})
obj = cursor.fetchone()
conn.commit()
cursor.close()
conn.close()print(obj)
数据库连接池版
setting.py
from datetime import timedelta
from redis import Redis
import pymysql
from DBUtils.PooledDB import PooledDB, SharedDBConnectionclass Config(object):DEBUG = TrueSECRET_KEY = "umsuldfsdflskjdf"PERMANENT_SESSION_LIFETIME = timedelta(minutes=20)SESSION_REFRESH_EACH_REQUEST= TrueSESSION_TYPE = "redis"PYMYSQL_POOL = PooledDB(creator=pymysql, # 使用链接数据库的模块maxconnections=6, # 连接池允许的最大连接数,0和None表示不限制连接数mincached=2, # 初始化时,链接池中至少创建的空闲的链接,0表示不创建maxcached=5, # 链接池中最多闲置的链接,0和None不限制maxshared=3,# 链接池中最多共享的链接数量,0和None表示全部共享。PS: 无用,因为pymysql和MySQLdb等模块的 threadsafety都为1,所有值无论设置为多少,_maxcached永远为0,所以永远是所有链接都共享。blocking=True, # 连接池中如果没有可用连接后,是否阻塞等待。True,等待;False,不等待然后报错maxusage=None, # 一个链接最多被重复使用的次数,None表示无限制setsession=[], # 开始会话前执行的命令列表。如:["set datestyle to ...", "set time zone ..."]ping=0,# ping MySQL服务端,检查是否服务可用。# 如:0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = alwayshost='127.0.0.1',port=3306,user='root',password='123456',database='s8day127db',charset='utf8')class ProductionConfig(Config):SESSION_REDIS = Redis(host='192.168.0.94', port='6379')class DevelopmentConfig(Config):SESSION_REDIS = Redis(host='127.0.0.1', port='6379')class TestingConfig(Config):pass
utils/sql.py
import pymysql
from settings import Config
class SQLHelper(object):@staticmethoddef open(cursor):POOL = Config.PYMYSQL_POOLconn = POOL.connection()cursor = conn.cursor(cursor=cursor)return conn,cursor@staticmethoddef close(conn,cursor):conn.commit()cursor.close()conn.close()@classmethoddef fetch_one(cls,sql,args,cursor =pymysql.cursors.DictCursor):conn,cursor = cls.open(cursor)cursor.execute(sql, args)obj = cursor.fetchone()cls.close(conn,cursor)return obj@classmethoddef fetch_all(cls,sql, args,cursor =pymysql.cursors.DictCursor):conn, cursor = cls.open(cursor)cursor.execute(sql, args)obj = cursor.fetchall()cls.close(conn, cursor)return obj
使用:
obj = SQLHelper.fetch_one("select id,name from users where name=%(user)s and pwd=%(pwd)s", form.data)
17.wtforms
安装:pip3 install wtforms
使用1:
from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgetsapp = Flask(__name__, template_folder='templates')app.debug = Trueclass LoginForm(Form):# 字段(内部包含正则表达式)name = simple.StringField(label='用户名',validators=[validators.DataRequired(message='用户名不能为空.'),validators.Length(min=6, max=18, message='用户名长度必须大于%(min)d且小于%(max)d')],widget=widgets.TextInput(), # 页面上显示的插件render_kw={'class': 'form-control'})# 字段(内部包含正则表达式)pwd = simple.PasswordField(label='密码',validators=[validators.DataRequired(message='密码不能为空.'),validators.Length(min=8, message='用户名长度必须大于%(min)d'),validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,}",message='密码至少8个字符,至少1个大写字母,1个小写字母,1个数字和1个特殊字符')],widget=widgets.PasswordInput(),render_kw={'class': 'form-control'})@app.route('/login', methods=['GET', 'POST'])
def login():if request.method == 'GET':form = LoginForm()return render_template('login.html', form=form)else:form = LoginForm(formdata=request.form)if form.validate():print('用户提交数据通过格式验证,提交的值为:', form.data)else:print(form.errors)return render_template('login.html', form=form)if __name__ == '__main__':app.run()
login.html
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<h1>登录</h1>
<form method="post"><p>{{form.name.label}} {{form.name}} {{form.name.errors[0] }}</p><p>{{form.pwd.label}} {{form.pwd}} {{form.pwd.errors[0] }}</p><input type="submit" value="提交">
</form>
</body>
</html>
使用2:
from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import core
from wtforms.fields import html5
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgetsapp = Flask(__name__, template_folder='templates')
app.debug = Trueclass RegisterForm(Form):name = simple.StringField(label='用户名',validators=[validators.DataRequired()],widget=widgets.TextInput(),render_kw={'class': 'form-control'},default='alex')pwd = simple.PasswordField(label='密码',validators=[validators.DataRequired(message='密码不能为空.')],widget=widgets.PasswordInput(),render_kw={'class': 'form-control'})pwd_confirm = simple.PasswordField(label='重复密码',validators=[validators.DataRequired(message='重复密码不能为空.'),validators.EqualTo('pwd', message="两次密码输入不一致")],widget=widgets.PasswordInput(),render_kw={'class': 'form-control'})email = html5.EmailField(label='邮箱',validators=[validators.DataRequired(message='邮箱不能为空.'),validators.Email(message='邮箱格式错误')],widget=widgets.TextInput(input_type='email'),render_kw={'class': 'form-control'})gender = core.RadioField(label='性别',choices=((1, '男'),(2, '女'),),coerce=int # “1” “2”)city = core.SelectField(label='城市',choices=(('bj', '北京'),('sh', '上海'),))hobby = core.SelectMultipleField(label='爱好',choices=((1, '篮球'),(2, '足球'),),coerce=int)favor = core.SelectMultipleField(label='喜好',choices=((1, '篮球'),(2, '足球'),),widget=widgets.ListWidget(prefix_label=False),option_widget=widgets.CheckboxInput(),coerce=int,default=[1, 2])def __init__(self, *args, **kwargs):super(RegisterForm, self).__init__(*args, **kwargs)self.favor.choices = ((1, '篮球'), (2, '足球'), (3, '羽毛球'))def validate_pwd_confirm(self, field):"""自定义pwd_confirm字段规则,例:与pwd字段是否一致:param field::return:"""# 最开始初始化时,self.data中已经有所有的值if field.data != self.data['pwd']:# raise validators.ValidationError("密码不一致") # 继续后续验证raise validators.StopValidation("密码不一致") # 不再继续后续验证@app.route('/register', methods=['GET', 'POST'])
def register():if request.method == 'GET':form = RegisterForm(data={'gender': 2,'hobby':[1,]}) # initialreturn render_template('register.html', form=form)else:form = RegisterForm(formdata=request.form)if form.validate():print('用户提交数据通过格式验证,提交的值为:', form.data)else:print(form.errors)return render_template('register.html', form=form)if __name__ == '__main__':app.run()
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body>
<h1>用户注册</h1>
<form method="post" novalidate style="padding:0 50px">{% for field in form %}<p>{{field.label}}: {{field}} {{field.errors[0] }}</p>{% endfor %}<input type="submit" value="提交">
</form>
</body>
</html>
18.信号
Flask框架中的信号基于blinker,其主要就是让开发者可是在flask请求过程中定制一些用户行为
安装:pip3 install blinker
内置信号:
request_started = _signals.signal('request-started') # 请求到来前执行
request_finished = _signals.signal('request-finished') # 请求结束后执行before_render_template = _signals.signal('before-render-template') # 模板渲染前执行
template_rendered = _signals.signal('template-rendered') # 模板渲染后执行got_request_exception = _signals.signal('got-request-exception') # 请求执行出现异常时执行request_tearing_down = _signals.signal('request-tearing-down') # 请求执行完毕后自动执行(无论成功与否)
appcontext_tearing_down = _signals.signal('appcontext-tearing-down')# 应用上下文执行完毕后自动执行(无论成功与否)appcontext_pushed = _signals.signal('appcontext-pushed') # 应用上下文push时执行
appcontext_popped = _signals.signal('appcontext-popped') # 应用上下文pop时执行
message_flashed = _signals.signal('message-flashed') # 调用flask在其中添加数据时,自动触发
使用信号:
from flask import Flask,signals,render_templateapp = Flask(__name__)# 往信号中注册函数
def func(*args,**kwargs):print('触发型号',args,kwargs)
signals.request_started.connect(func)# 触发信号: signals.request_started.send()
@app.before_first_request
def before_first1(*args,**kwargs):pass
@app.before_first_request
def before_first2(*args,**kwargs):pass@app.before_request
def before_first3(*args,**kwargs):pass@app.route('/',methods=['GET',"POST"])
def index():print('视图')return render_template('index.html')if __name__ == '__main__':app.wsgi_appapp.run()
一个流程中的信号触发点(了解)
a. before_first_request
b. 触发 request_started 信号
c. before_request
d. 模板渲染渲染前的信号 before_render_template.send(app, template=template, context=context)rv = template.render(context) # 模板渲染渲染后的信号 template_rendered.send(app, template=template, context=context)
e. after_request
f. session.save_session()
g. 触发 request_finished信号 如果上述过程出错:触发错误处理信号 got_request_exception.send(self, exception=e)h. 触发信号 request_tearing_down
自定义信号(了解):
from flask import Flask, current_app, flash, render_template
from flask.signals import _signals
app = Flask(import_name=__name__)# 自定义信号
xxxxx = _signals.signal('xxxxx')def func(sender, *args, **kwargs):print(sender)
# 自定义信号中注册函数
xxxxx.connect(func)
@app.route("/x")
def index():# 触发信号xxxxx.send('123123', k1='v1')return 'Index' if __name__ == '__main__':app.run()
19.多app应用
from werkzeug.wsgi import DispatcherMiddleware
from werkzeug.serving import run_simple
from flask import Flask, current_app
app1 = Flask('app01')
app2 = Flask('app02')@app1.route('/index')
def index():return "app01"@app2.route('/index2')
def index2():return "app2"# http://www.oldboyedu.com/index
# http://www.oldboyedu.com/sec/index2
dm = DispatcherMiddleware(app1, {'/sec': app2,
})if __name__ == "__main__":run_simple('localhost', 5000, dm)
20.flask-script
用于实现类似于django中 python3 manage.py runserver ...类似的命令
安装:pip3 install flask-script
使用
from flask_script import Manager
app = Flask(__name__)
manager=Manager(app)
...
if __name__ == '__main__':manager.run()
#以后在执行,直接:python3 manage.py runserver
#python3 manage.py runserver --help
自定制命令
@manager.command
def custom(arg):"""自定义命令python manage.py custom 123:param arg::return:"""print(arg)@manager.option('-n', '--name', dest='name')
#@manager.option('-u', '--url', dest='url')
def cmd(name, url):"""自定义命令(-n也可以写成--name)执行: python manage.py cmd -n lqz -u http://www.oldboyedu.com执行: python manage.py cmd --name lqz --url http://www.oldboyedu.com:param name::param url::return:"""print(name, url)
#有什么用?
#把excel的数据导入数据库,定制个命令,去执行
21flask-admin
安装
pip3 install flask_admin
简单使用
from flask import Flask
from flask_admin import Adminapp = Flask(__name__)
#将app注册到adminzhong
admin = Admin(app)if __name__=="mian":app.run()
#访问
#127.0.0.1:5000/admin端口,会得到一个空白的页面
将表模型注册到admin中
#在将表注册之前应该对app进行配置
SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:@127.0.0.1:3307/py9api?charset=utf8mb4"
SQLALCHEMY_POOL_SIZE = 5
SQLALCHEMY_POOL_TIMEOUT = 30
SQLALCHEMY_POOL_RECYCLE = -1#导入models文件的中的表模型
from flask_admin.contrib.sqla import ModelView
from api.models import Stock,Product,Images,Category,Wxuser,Banneradmin.add_view(ModelView(Stock, db.session))
admin.add_view(ModelView(Product, db.session))admin.add_view(ModelView(Category, db.session))
如果有个字段是图片指端
#配置上传文件的路径
#导入from flask_admin.contrib.fileadmin import FileAdmin
from flask_admin.contrib.fileadmin import FileAdmin,form
file_path = op.join(op.dirname(__file__), 'static')
admin = Admin(app)
admin.add_view(FileAdmin(file_path, '/static/', name='文件'))#如果有个字段要是上传文件重写该方法的modleView类,假设imgae_url是文件图片的字段
class ImagesView(ModelView):form_extra_fields = {'image_url': form.ImageUploadField('Image',base_path=file_path,relative_path='uploadFile/')}admin.add_view(ImagesView(Images, db.session))