Flask学习之基础知识与功能
Posted chenjunkan
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一：flask的背景介绍
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。
二：基本功能使用
1.补充：学习flask首先要了解装饰器的使用方式
a：不带参数的装饰器
1 定义一个装饰器函数： 2 def wrapper(func): 3 def inner(*args, **kwargs): 4 return func(*args, **kwargs) 5 return inner 6 7 用装饰器wrapper函数装饰index函数 8 @wrapper 9 def index(request): 10 pass 11 12 说明：执行@wrapper装饰器等价于：index = wrapper(index)，返回值是inner
b：带参数的装饰器
1 定义一个带参数的装饰器函数： 2 def route(option): 3 def inner(func,*args, **kwargs): 4 url_map[option[‘path‘]] = func 5 return inner 6 7 用route函数装饰index函数，并传入参数 8 @route({‘path‘:‘/index‘}) 9 def index(request): 10 11 说明： 12 1.首先会执行route函数，将对应的参数{‘path‘:‘/index‘}传入，得到route函数的返回值inner 13 2.执行@inner等价于：inner = inner(index),此时：inner函数中的func = index;*args, **kwarg里面的参数值等于我们传入的值{‘path‘:‘/index‘}，因为是参数是字典的格式，因此是通过**kwargs传入的。 14 3.执行url_map[option[‘path‘]] = func，等价于下面的路由关系 15 url_map = { 16 ‘/index‘: index 17 }
c：设置元信息
1 mport functools 2 3 def wapper(func): 4 5 @functools.wraps(func) # 帮助我们设置函数的元信息 6 def inner(*args,**kwargs): 7 return func(*args,**kwargs) 8 9 return inner 10 11 @wapper 12 def f1(): 13 pass 14 15 @wapper 16 def f2(): 17 pass 18 19 print(f1.__name__) 20 print(f2.__name__)
2.三大python主流的框架对比：
Django：重武器，内部包含了非常多组件：ORM、Form、ModelForm、缓存、Session、中间件、信号等...
Flask：短小精悍，内部没有太多组件。第三方组件非常丰富。路由比较特殊：基于装饰器来实现，但是究其本质还是通过add_url_rule来实现。
Tornado：异步非阻塞框架（node.js）
3.安装：pip3 install flask
4.本质：Werkzeug WSGI
1 werkzeug示例： 2 from werkzeug.wrappers import Request, Response 3 @Request.application 4 def hello(request): 5 return Response(‘Hello World!‘) 6 7 if __name__ == ‘__main__‘: 8 from werkzeug.serving import run_simple 9 run_simple(‘localhost‘, 4000, hello) 10 11 wsgiref示例： 12 from wsgiref.simple_server import make_server 13 def runserver(environ, start_response): 14 start_response(‘200 OK‘, [(‘Content-Type‘, ‘text/html‘)]) 15 return [bytes(‘<h1>Hello, web!</h1>‘,encoding=‘utf-8‘), ] 16 17 if __name__ == ‘__main__‘: 18 # obj = WSGIHandler() 19 httpd = make_server(‘‘, 8000, runserver) 20 httpd.serve_forever()
本质的本质：Werkzeug本质是Socket服务端
1 import socket 2 3 def handle_request(client): 4 buf = client.recv(1024) 5 client.send("HTTP/1.1 200 OK ") 6 client.send("Hello, Seven") 7 8 def main(): 9 sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 10 sock.bind((‘localhost‘,8000)) 11 sock.listen(5) 12 13 while True: 14 connection, address = sock.accept() 15 handle_request(connection) 16 connection.close() 17 18 if __name__ == ‘__main__‘: 19 main()
5.基本使用
1 from flask import Flask 2 3 # 实例化Flask对象app 4 5 app = Flask(__name__) 6 7 # 设置路由关系 8 9 { 10 11 ‘/‘：index 12 13 } 14 15 @app.route("/") 16 17 def hello_world(): 18 return "hello world" 19 if __name__=="__main__": 20 app.run()
6.配置文件
1 flask中的配置文件是一个flask.config.Config对象（继承字典）,默认配置为： 2 { 3 ‘DEBUG‘: get_debug_flag(default=False), 是否开启Debug模式 4 ‘TESTING‘: False, 是否开启测试模式 5 ‘PROPAGATE_EXCEPTIONS‘: None, 6 ‘PRESERVE_CONTEXT_ON_EXCEPTION‘: None, 7 ‘SECRET_KEY‘: None, 8 ‘PERMANENT_SESSION_LIFETIME‘: timedelta(days=31), 9 ‘USE_X_SENDFILE‘: False, 10 ‘LOGGER_NAME‘: None, 11 ‘LOGGER_HANDLER_POLICY‘: ‘always‘, 12 ‘SERVER_NAME‘: None, 13 ‘APPLICATION_ROOT‘: None, 14 ‘SESSION_COOKIE_NAME‘: ‘session‘, 15 ‘SESSION_COOKIE_DOMAIN‘: None, 16 ‘SESSION_COOKIE_PATH‘: None, 17 ‘SESSION_COOKIE_HTTPONLY‘: True, 18 ‘SESSION_COOKIE_SECURE‘: False, 19 ‘SESSION_REFRESH_EACH_REQUEST‘: True, 20 ‘MAX_CONTENT_LENGTH‘: None, 21 ‘SEND_FILE_MAX_AGE_DEFAULT‘: timedelta(hours=12), 22 ‘TRAP_BAD_REQUEST_ERRORS‘: False, 23 ‘TRAP_HTTP_EXCEPTIONS‘: False, 24 ‘EXPLAIN_TEMPLATE_LOADING‘: False, 25 ‘PREFERRED_URL_SCHEME‘: ‘http‘, 26 ‘JSON_AS_ASCII‘: True, 27 ‘JSON_SORT_KEYS‘: True, 28 ‘JSONIFY_PRETTYPRINT_REGULAR‘: True, 29 ‘JSONIFY_MIMETYPE‘: ‘application/json‘, 30 ‘TEMPLATES_AUTO_RELOAD‘: None, 31 } 32 33 方式一： 34 app.config[‘DEBUG‘] = True 35 36 PS： 由于Config对象本质上是字典，所以还可以使用app.config.update(...) 37 38 方式二： 39 app.config.from_pyfile("python文件名称") 40 如： 41 settings.py 42 DEBUG = True 43 44 app.config.from_pyfile("settings.py") 45 46 app.config.from_envvar("环境变量名称") 47 环境变量的值为python文件名称名称，内部调用from_pyfile方法 48 49 50 app.config.from_json("json文件名称") 51 JSON文件名称，必须是json格式，因为内部会执行json.loads 52 53 app.config.from_mapping({‘DEBUG‘:True}) 54 字典格式 55 56 一般的情况下使用对象的情况较多 57 app.config.from_object("python类或类的路径") 58 59 app.config.from_object(‘pro_flask.settings.TestingConfig‘) 60 61 settings.py 62 63 class Config(object): 64 DEBUG = False 65 TESTING = False 66 DATABASE_URI = ‘sqlite://:memory:‘ 67 68 class ProductionConfig(Config): 69 DATABASE_URI = ‘mysql://[email protected]/foo‘ 70 71 class DevelopmentConfig(Config): 72 DEBUG = True 73 74 class TestingConfig(Config): 75 TESTING = True 76 77 PS: 从sys.path中已经存在路径开始写 78 79 80 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
代码示例：
写一个setting.py的文件用来项目所需要的配置：
1 class Config(object): 2 DEBUG = False 3 TESTING = False 4 DATABASE_URI = ‘sqlite://:memory:‘ 5 6 # 生产环境 7 class ProductionConfig(Config): 8 DATABASE_URI = ‘mysql://[email protected]/foo‘ 9 10 #开发环境 11 class DevelopmentConfig(Config): 12 DEBUG = True 13 14 #测试环境 15 class TestingConfig(Config): 16 TESTING = True
使用：
1 from flask import Flask 2 3 app = Flask(__name__) 4 app.debug = True 5 app.secret_key = "asdfasdf" 6 7 # 通过app.confgi.from_object 8 app.config.from_object("settings.DevelopmentConfig") 9 10 @app.route(‘/‘) 11 def index(): 12 return ‘Hello World!‘ 13 14 if __name__ == ‘__main__‘: 15 app.run()
7.路由系统
- @app.route(‘/user/<username>‘) # 带字符串的参数
- @app.route(‘/post/<int:post_id>‘)# 带int类型的参数
- @app.route(‘/post/<float:post_id>‘)# 带float类型的参数
- @app.route(‘/post/<path:path>‘)# 带其他的路径
- @app.route(‘/login‘, methods=[‘GET‘, ‘POST‘]) # 带提交请求的方式
a.路由的源码：
1 源码： 2 def route(self, rule, **options): 3 def decorator(f): 4 endpoint = options.pop(‘endpoint‘, None) 5 self.add_url_rule(rule, endpoint, f, **options) 6 return f 7 return decorator 8 9 说明：1.当视图函数被app.route函数执行的时候，实际上视图函数被route装饰器装饰，返回的值为decorator;相当于decorator = app.route(‘/‘,methods=[‘GET‘,‘POST‘],endpoint=‘n1‘) 10 11 2.然后再执行@decorator，将参数传进去
b.示例代码：
1 from flask import Flask 2 3 app = Flask(__name__) 4 app.debug = True 5 app.secret_key = "asdfasdf" 6 7 """ 8 1. decorator = app.route(‘/‘,methods=[‘GET‘,‘POST‘],endpoint=‘n1‘) 9 def route(self, rule, **options): 10 # self：app对象 11 # rule= / 12 # options = {methods=[‘GET‘,‘POST‘],endpoint=‘n1‘} 13 def decorator(f): 14 endpoint = options.pop(‘endpoint‘, None) 15 self.add_url_rule(rule, endpoint, f, **options) 16 return f 17 return decorator 18 2. @decorator 19 decorator(index) 20 """ 21 @app.route(‘/‘,methods=[‘GET‘,‘POST‘],endpoint=‘n1‘) 22 def index(): 23 return ‘Hello World!‘ 24 25 26 def login(): 27 return ‘登录‘ 28 29 app.add_url_rule(‘/login‘, ‘n2‘, login, methods=[‘GET‘,"POST"]) 30 31 32 if __name__ == ‘__main__‘: 33 app.run()
c.注册路由的基本原理与路由用到的参数
1 1.基于CBV的路由： 2 def auth(func): 3 def inner(*args, **kwargs): 4 print(‘before‘) 5 result = func(*args, **kwargs) 6 print(‘after‘) 7 return result 8 9 return inner 10 11 class IndexView(views.View): 12 methods = [‘GET‘] 13 decorators = [auth, ] 14 15 def dispatch_request(self): 16 print(‘Index‘) 17 return ‘Index!‘ 18 19 app.add_url_rule(‘/index‘, view_func=IndexView.as_view(name=‘index‘)) # name=endpoint 20 21 2.路由的基本参数： 22 @app.route和app.add_url_rule参数： 23 rule, URL规则 24 view_func, 视图函数名称 25 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 26 endpoint=None, 名称，用于反向生成URL，即： url_for(‘名称‘) 27 methods=None, 允许的请求方式，如：["GET","POST"] 28 29 30 strict_slashes=None, 对URL最后的 / 符号是否严格要求， 31 如： 32 @app.route(‘/index‘,strict_slashes=False)， 33 访问 http://www.xx.com/index/ 或 http://www.xx.com/index均可 34 @app.route(‘/index‘,strict_slashes=True) 35 仅访问 http://www.xx.com/index 36 redirect_to=None, 重定向到指定地址 37 如： 38 @app.route(‘/index/<int:nid>‘, redirect_to=‘/home/<nid>‘) 39 或 40 def func(adapter, nid): 41 return "/home/888" 42 @app.route(‘/index/<int:nid>‘, redirect_to=func) 43 subdomain=None, 子域名访问 44 from flask import Flask, views, url_for 45 46 app = Flask(import_name=__name__) 47 app.config[‘SERVER_NAME‘] = ‘wupeiqi.com:5000‘ 48 49 50 @app.route("/", subdomain="admin") 51 def static_index(): 52 """Flask supports static subdomains 53 This is available at static.your-domain.tld""" 54 return "static.your-domain.tld" 55 56 57 @app.route("/dynamic", subdomain="<username>") 58 def username_index(username): 59 """Dynamic subdomains are also supported 60 Try going to user1.your-domain.tld/dynamic""" 61 return username + ".your-domain.tld" 62 63 64 if __name__ == ‘__main__‘: 65 app.run() 66
d.CVB示例代码：
1 from flask import Flask,views 2 3 app = Flask(__name__) 4 app.debug = True 5 app.secret_key = "asdfasdf" 6 7 8 def auth(func): 9 def inner(*args, **kwargs): 10 result = func(*args, **kwargs) 11 return result 12 return inner 13 14 class IndexView(views.MethodView): 15 methods = [‘GET‘] 16 decorators = [auth, ] 17 18 def get(self): 19 return ‘Index.GET‘ 20 21 def post(self): 22 return ‘Index.POST‘ 23 24 app.add_url_rule(‘/index‘, view_func=IndexView.as_view(name=‘index‘)) # name=endpoint 25 26 27 if __name__ == ‘__main__‘: 28 app.run()
e.路由参数中redirect_to与defaults的示例代码：
1 from flask import Flask 2 3 app = Flask(__name__) 4 app.debug = True 5 app.secret_key = "asdfasdf" 6 7 8 # @app.route(‘/‘,methods=[‘GET‘,‘POST‘],endpoint=‘n1‘,defaults={‘nid‘:888}) 9 # def index(nid): 10 # print(nid) 11 # return ‘Hello World!‘ 12 # 13 # 14 # def login(): 15 # return ‘登录‘ 16 # app.add_url_rule(‘/login‘, ‘n2‘, login, methods=[‘GET‘,"POST"]) 17 18 19 @app.route(‘/index‘, methods=[‘GET‘, ‘POST‘], endpoint=‘n1‘, redirect_to="/index2") 20 def index(): 21 return ‘公司老首页‘ 22 23 24 @app.route(‘/index2‘, methods=[‘GET‘, ‘POST‘], endpoint=‘n2‘) 25 def index2(): 26 return ‘公司新首页‘ 27 28 29 if __name__ == ‘__main__‘: 30 app.run()
f：路由参数中subdomain的示例代码：
1 from flask import Flask, views, url_for 2 3 app = Flask(import_name=__name__) 4 app.config[‘SERVER_NAME‘] = ‘chenjunkan.com:5000‘ 5 6 7 @app.route("/", subdomain="admin") 8 def static_index(): 9 """Flask supports static subdomains 10 This is available at static.your-domain.tld""" 11 return "xxxxxx.your-domain.tld" 12 13 14 @app.route("/dynamic", subdomain="<username>") 15 def username_index(username): 16 """Dynamic subdomains are also supported 17 Try going to user1.your-domain.tld/dynamic""" 18 return username + ".your-domain.tld" 19 20 21 if __name__ == ‘__main__‘: 22 app.run()
g：自定义正则路由匹配
1 from flask import Flask, views, url_for 2 from werkzeug.routing import BaseConverter 3 4 app = Flask(import_name=__name__) 5 6 7 class RegexConverter(BaseConverter): 8 """ 9 自定义URL匹配正则表达式 10 """ 11 def __init__(self, map, regex): 12 super(RegexConverter, self).__init__(map) 13 self.regex = regex 14 15 def to_python(self, value): 16 """ 17 路由匹配时，匹配成功后传递给视图函数中参数的值 18 :param value: 19 :return: 20 """ 21 return int(value) 22 23 def to_url(self, value): 24 """ 25 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 26 :param value: 27 :return: 28 """ 29 val = super(RegexConverter, self).to_url(value) 30 return val 31 32 # 添加到flask中 33 app.url_map.converters[‘regex‘] = RegexConverter 34 35 36 @app.route(‘/index/<regex("d+"):nid>‘) 37 def index(nid): 38 print(url_for(‘index‘, nid=‘888‘)) 39 return ‘Index‘ 40 41 42 if __name__ == ‘__main__‘: 43 app.run()
8.模板
1、模板的使用
Flask使用的是Jinja2模板，所以其语法和Django无差别
2、自定义模板方法
Flask中自定义模板方法的方式和Bottle相似，创建一个函数并通过参数的形式传入render_template
注意：Markup等价django的mark_safe
9.请求跟响应
1 from flask import Flask 2 from flask import request 3 from flask import render_template 4 from flask import redirect 5 from flask import make_response 6 7 app = Flask(__name__) 8 9 10 @app.route(‘/login.html‘, methods=[‘GET‘, "POST"]) 11 def login(): 12 13 # 请求相关信息 14 # request.method 15 # request.args 16 # request.form 17 # request.values 18 # request.cookies 19 # request.headers 20 # request.path 21 # request.full_path 22 # request.script_root 23 # request.url 24 # request.base_url 25 # request.url_root 26 # request.host_url 27 # request.host 28 # request.files 29 # obj = request.files[‘the_file_name‘] 30 # obj.save(‘/var/www/uploads/‘ + secure_filename(f.filename)) 31 32 # 响应相关信息 33 # return "字符串" 34 # return render_template(‘html模板路径‘,**{}) 35 # return redirect(‘/index.html‘) 36 37 # response = make_response(render_template(‘index.html‘)) 38 # response是flask.wrappers.Response类型 39 # response.delete_cookie(‘key‘) 40 # response.set_cookie(‘key‘, ‘value‘) 41 # response.headers[‘X-Something‘] = ‘A value‘ 42 # return response 43 44 45 return "内容" 46 47 if __name__ == ‘__main__‘: 48 app.run()
10：session的使用
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。
-
设置：session[‘username‘] ＝ ‘xxx‘
- 删除：session.pop(‘username‘, None)
a.基本使用
1 from flask import Flask, session, redirect, url_for, escape, request 2 3 app = Flask(__name__) 4 5 @app.route(‘/‘) 6 def index(): 7 if ‘username‘ in session: 8 return ‘Logged in as %s‘ % escape(session[‘username‘]) 9 return ‘You are not logged in‘ 10 11 @app.route(‘/login‘, methods=[‘GET‘, ‘POST‘]) 12 def login(): 13 if request.method == ‘POST‘: 14 session[‘username‘] = request.form[‘username‘] 15 return redirect(url_for(‘index‘)) 16 return ‘‘‘ 17 <form action="" method="post"> 18 <p><input type=text name=username> 19 <p><input type=submit value=Login> 20 </form> 21 ‘‘‘ 22 23 @app.route(‘/logout‘) 24 def logout(): 25 # remove the username from the session if it‘s there 26 session.pop(‘username‘, None) 27 return redirect(url_for(‘index‘)) 28 29 # set the secret key. keep this really secret: 30 app.secret_key = ‘A0Zr98j/3yX R~XHH!jmN]LWX/,?RT‘
b.自定义session，后续的请求上下文中会详细介绍Flask-Session
1 pip3 install Flask-Session 2 3 run.py 4 from flask import Flask 5 from flask import session 6 from pro_flask.utils.session import MySessionInterface 7 app = Flask(__name__) 8 9 app.secret_key = ‘A0Zr98j/3yX R~XHH!jmN]LWX/,?RT‘ 10 app.session_interface = MySessionInterface() 11 12 @app.route(‘/login.html‘, methods=[‘GET‘, "POST"]) 13 def login(): 14 print(session) 15 session[‘user1‘] = ‘alex‘ 16 session[‘user2‘] = ‘alex‘ 17 del session[‘user2‘] 18 19 return "内容" 20 21 if __name__ == ‘__main__‘: 22 app.run() 23 24 session.py 25 #!/usr/bin/env python 26 # -*- coding:utf-8 -*- 27 import uuid 28 import json 29 from flask.sessions import SessionInterface 30 from flask.sessions import SessionMixin 31 from itsdangerous import Signer, BadSignature, want_bytes 32 33 34 class MySession(dict, SessionMixin): 35 def __init__(self, initial=None, sid=None): 36 self.sid = sid 37 self.initial = initial 38 super(MySession, self).__init__(initial or ()) 39 40 41 def __setitem__(self, key, value): 42 super(MySession, self).__setitem__(key, value) 43 44 def __getitem__(self, item): 45 return super(MySession, self).__getitem__(item) 46 47 def __delitem__(self, key): 48 super(MySession, self).__delitem__(key) 49 50 51 52 class MySessionInterface(SessionInterface): 53 session_class = MySession 54 container = {} 55 56 def __init__(self): 57 import redis 58 self.redis = redis.Redis() 59 60 def _generate_sid(self): 61 return str(uuid.uuid4()) 62 63 def _get_signer(self, app): 64 if not app.secret_key: 65 return None 66 return Signer(app.secret_key, salt=‘flask-session‘, 67 key_derivation=‘hmac‘) 68 69 def open_session(self, app, request): 70 """ 71 程序刚启动时执行，需要返回一个session对象 72 """ 73 sid = request.cookies.get(app.session_cookie_name) 74 if not sid: 75 sid = self._generate_sid() 76 return self.session_class(sid=sid) 77 78 signer = self._get_signer(app) 79 try: 80 sid_as_bytes = signer.unsign(sid) 81 sid = sid_as_bytes.decode() 82 except BadSignature: 83 sid = self._generate_sid() 84 return self.session_class(sid=sid) 85 86 # session保存在redis中 87 # val = self.redis.get(sid) 88 # session保存在内存中 89 val = self.container.get(sid) 90 91 if val is not None: 92 try: 93 data = json.loads(val) 94 return self.session_class(data, sid=sid) 95 except: 96 return self.session_class(sid=sid) 97 return self.session_class(sid=sid) 98 99 def save_session(self, app, session, response): 100 """ 101 程序结束前执行，可以保存session中所有的值 102 如： 103 保存到resit 104 写入到用户cookie 105 """ 106 domain = self.get_cookie_domain(app) 107 path = self.get_cookie_path(app) 108 httponly = self.get_cookie_httponly(app) 109 secure = self.get_cookie_secure(app) 110 expires = self.get_expiration_time(app, session) 111 112 val = json.dumps(dict(session)) 113 114 # session保存在redis中 115 # self.redis.setex(name=session.sid, value=val, time=app.permanent_session_lifetime) 116 # session保存在内存中 117 self.container.setdefault(session.sid, val) 118 119 session_id = self._get_signer(app).sign(want_bytes(session.sid)) 120 121 response.set_cookie(app.session_cookie_name, session_id, 122 expires=expires, httponly=httponly, 123 domain=domain, path=path, secure=secure)
c：第三方的session
1 """ 2 pip3 install redis 3 pip3 install flask-session 4 5 """ 6 7 8 from flask import Flask, session, redirect 9 from flask.ext.session import Session 10 11 12 app = Flask(__name__) 13 app.debug = True 14 app.secret_key = ‘asdfasdfasd‘ 15 16 17 app.config[‘SESSION_TYPE‘] = ‘redis‘ 18 from redis import Redis 19 app.config[‘SESSION_REDIS‘] = Redis(host=‘192.168.0.94‘,port=‘6379‘) 20 Session(app) 21 22 23 @app.route(‘/login‘) 24 def login(): 25 session[‘username‘] = ‘alex‘ 26 return redirect(‘/index‘) 27 28 29 @app.route(‘/index‘) 30 def index(): 31 name = session[‘username‘] 32 return name 33 34 35 if __name__ == ‘__main__‘: 36 app.run()
11：Blueprint
- 蓝图URL前缀：xxx = Blueprint(‘account‘, __name__,url_prefix=‘/xxx‘)
- 蓝图子域名：xxx = Blueprint(‘account‘, __name__,subdomain=‘admin‘)
示例代码：
12：message
message是一个基于Session实现的用于保存数据的集合，其特点是：使用一次就删除。
1 from flask import Flask, flash, redirect, render_template, request, get_flashed_messages 2 3 app = Flask(__name__) 4 app.secret_key = ‘some_secret‘ 5 6 7 @app.route(‘/‘) 8 def index1(): 9 messages = get_flashed_messages() 10 print(messages) 11 return "Index1" 12 13 14 @app.route(‘/set‘) 15 def index2(): 16 v = request.args.get(‘p‘) 17 flash(v) 18 return ‘ok‘ 19 20 21 if __name__ == "__main__": 22 app.run()
13：中间件
1 from flask import Flask, flash, redirect, render_template, request 2 3 app = Flask(__name__) 4 app.secret_key = ‘some_secret‘ 5 6 @app.route(‘/‘) 7 def index1(): 8 return render_template(‘index.html‘) 9 10 @app.route(‘/set‘) 11 def index2(): 12 v = request.args.get(‘p‘) 13 flash(v) 14 return ‘ok‘ 15 16 class MiddleWare: 17 def __init__(self,wsgi_app): 18 self.wsgi_app = wsgi_app 19 20 def __call__(self, *args, **kwargs): 21 22 return self.wsgi_app(*args, **kwargs) 23 24 if __name__ == "__main__": 25 app.wsgi_app = MiddleWare(app.wsgi_app) 26 app.run(port=9999)
14：请求扩展
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 from flask import Flask, Request, render_template 4 5 app = Flask(__name__, template_folder=‘templates‘) 6 app.debug = True 7 8 9 @app.before_first_request 10 def before_first_request1(): 11 print(‘before_first_request1‘) 12 13 14 @app.before_first_request 15 def before_first_request2(): 16 print(‘before_first_request2‘) 17 18 19 @app.before_request 20 def before_request1(): 21 Request.nnn = 123 22 print(‘before_request1‘) 23 24 25 @app.before_request 26 def before_request2(): 27 print(‘before_request2‘) 28 29 30 @app.after_request 31 def after_request1(response): 32 print(‘before_request1‘, response) 33 return response 34 35 36 @app.after_request 37 def after_request2(response): 38 print(‘before_request2‘, response) 39 return response 40 41 42 @app.errorhandler(404) 43 def page_not_found(error): 44 return ‘This page does not exist‘, 404 45 46 47 @app.template_global() 48 def sb(a1, a2): 49 return a1 + a2 50 51 52 @app.template_filter() 53 def db(a1, a2, a3): 54 return a1 + a2 + a3 55 56 57 @app.route(‘/‘) 58 def hello_world(): 59 return render_template(‘hello.html‘) 60 61 62 if __name__ == ‘__main__‘: 63 app.run()
15：flask插件
http://flask.pocoo.org/extensions/
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