Flask详解
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。
pip3 install flask
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from werkzeug.wrappers import Request, Response @Request.application def hello(request): return Response('Hello World!') if __name__ == '__main__': from werkzeug.serving import run_simple run_simple('localhost', 4000, hello)
一. 基本使用
from flask import Flask app = Flask(__name__) @app.route('/') def hello_world(): return 'Hello World!' if __name__ == '__main__': app.run()
flask添加装饰器
from flask import Flask import functools def auth(func): @functools.wraps(func) # 保留函数的元信息 def inner(*args,**kwargs): print('before') ret = func(*args,**kwargs) print('after') return ret return inner app = Flask(__name__) @app.route('/index') @auth def index(): print('index') return 'index' if __name__ == '__main__': app.run()
指定端口号
from werkzeug.wrappers import Request, Response from werkzeug.serving import run_simple @Request.application def hello(request): # ... # Flask框架 # return Response('Hello World!') if __name__ == '__main__': run_simple('localhost', 4000, hello) # hello()
示例:before_request和after_request
from flask import Flask,render_template,request,redirect,session app = Flask(__name__) app.secret_key = '39jrlasdfoajslfu8af' # [b1,b2] @app.before_request def b1(): print('b1') return 'gun' @app.before_request def b2(): print('b2') # [a1,a2] -> [a2,a1] @app.after_request def a1(response): print('a1') return response @app.after_request def a2(response): print('a2') return response @app.route('/index') def index(): print('index') return 'index' if __name__ == '__main__': app.run()
基于装饰器做用户认证
from flask import Flask,render_template,request,redirect,session app = Flask(__name__) app.secret_key = '39jrlasdfoajslfu8af' import functools def auth(func): @functools.wraps(func) # 保留函数的元信息 一定要记得添加这行代码 def inner(*args,**kwargs): if not session.get('user_info'): return redirect('/login') ret = func(*args,**kwargs) return ret return inner @app.route('/login',methods=['GET','POST']) def login(): if request.method == 'GET': return render_template('login.html') user = request.form.get('user') pwd = request.form.get('pwd') if user == 'xiao' and pwd == 'xiao': session['user_info'] = user return redirect('/index') return render_template('login.html',msg="用户名或密码错误") @app.route('/index') @auth def index(): kuang_list = [ {'id':1,'name':'name1','address':'昌平'}, {'id':2,'name':'name2','address':'昌平'}, {'id':3,'name':'name3','address':'昌平'}, ] return render_template('index.html',klist=kuang_list) # return render_template('index.html',**{'klist':kuang_list}) @app.route('/detail') @auth def detail(): nid = request.args.get('nid') return render_template('detail.html') @app.route('/logout') def logout(): del session['user_info'] return redirect('/login') if __name__ == '__main__': app.run()
基于before_request实现用户认证
from flask import Flask,render_template,request,redirect,session app = Flask(__name__) app.secret_key = '39jrlasdfoajslfu8af' @app.before_request def xxxxxxxxxxxxxx(): if request.path == '/login': return None if not session.get('user_info'): return redirect('/login') @app.route('/login',methods=['GET','POST']) def login(): print('我是login') if request.method == 'GET': return render_template('login.html') user = request.form.get('user') pwd = request.form.get('pwd') if user == 'xiao' and pwd == 'xiao': session['user_info'] = user return redirect('/index') return render_template('login.html',msg="用户名或密码错误") @app.route('/index') def index(): print('我是index') kuang_list = [ {'id':1,'name':'name1','address':'昌平'}, {'id':2,'name':'name2','address':'昌平'}, {'id':3,'name':'name3','address':'昌平'}, ] return render_template('index.html',klist=kuang_list) # 这种传参方式,要注意 # return render_template('index.html',**{'klist':kuang_list}) # 这种传参方式,要加**打散 @app.route('/detail') def detail(): nid = request.args.get('nid') return render_template('detail.html') @app.route('/logout') def logout(): del session['user_info'] return redirect('/login') if __name__ == '__main__': app.run()
二、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'] = True PS: 由于Config对象本质上是字典,所以还可以使用app.config.update(...) 方式二: app.config.from_pyfile("python文件名称") 如: settings.py DEBUG = True app.config.from_pyfile("settings.py") app.config.from_envvar("环境变量名称") 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.loads app.config.from_mapping({'DEBUG':True}) 字典格式 app.config.from_object("python类或类的路径") # 写在flask启动的py文件里面进行配置版本 app.config.from_object('pro_flask.settings.TestingConfig') settings.py class Config(object): # 基础版本 DEBUG = False TESTING = False DATABASE_URI = 'sqlite://:memory:' class ProductionConfig(Config): # 生产环境,线下环境 DATABASE_URI = 'mysql://user@localhost/foo' class DevelopmentConfig(Config): # 开发环境 DEBUG = True class TestingConfig(Config): # 测试环境 各个环境下连接的数据库是不一样的 TESTING = True PS: 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
三、路由系统
- @app.route('/user/<username>') # 传字符串 他们的内部都对应一个转换器
- @app.route('/post/<int:post_id>') # 传数字
- @app.route('/post/<float:post_id>') # 浮点数
- @app.route('/post/<path:path>') # 路径,拼url
- @app.route('/login', methods=['GET', 'POST']),method列表里面添加的允许的请求方式,如果不添加method列表,则只允许GET请求。
常用路由系统有以上五种,所有的路由系统都是基于一下对应关系来处理:
DEFAULT_CONVERTERS = { 'default': UnicodeConverter, 'string': UnicodeConverter, 'any': AnyConverter, 'path': PathConverter, 'int': IntegerConverter, 'float': FloatConverter, 'uuid': UUIDConverter, }
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def auth(func): def inner(*args, **kwargs): print('before') result = func(*args, **kwargs) print('after') return result return inner @app.route('/index.html',methods=['GET','POST'],endpoint='index') @auth def index(): return 'Index' 或 def index(): return "Index" self.add_url_rule(rule='/index.html', endpoint="index", view_func=index, methods=["GET","POST"]) or app.add_url_rule(rule='/index.html', endpoint="index", view_func=index, methods=["GET","POST"]) app.view_functions['index'] = index 或 def auth(func): def inner(*args, **kwargs): print('before') result = func(*args, **kwargs) print('after') return result return inner class 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 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.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"] strict_slashes=None, 对URL最后的 / 符号是否严格要求, 如: @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 redirect_to=None, 重定向到指定地址 如: @app.route('/index/<int:nid>', redirect_to='/home/<nid>') 或 def func(adapter, nid): return "/home/888" @app.route('/index/<int:nid>', redirect_to=func) subdomain=None, 子域名访问 from flask import Flask, views, url_for app = Flask(import_name=__name__) app.config['SERVER_NAME'] = 'wupeiqi.com:5000' @app.route("/", subdomain="admin") def static_index(): """Flask supports static subdomains This is available at static.your-domain.tld""" return "static.your-domain.tld" @app.route("/dynamic", subdomain="<username>") def username_index(username): """Dynamic subdomains are also supported Try going to user1.your-domain.tld/dynamic""" return username + ".your-domain.tld" if __name__ == '__main__': app.run()
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from flask import Flask, views, url_for from werkzeug.routing import BaseConverter app = 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 = regex def 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 :param value: :return: """ 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 :param value: :return: """ 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()
app.url_map.converters['regex'] = RegexConverter # 这个写在启动py文件里,告诉flask我自己要定义一个路由转换器啦,名字叫regex # 转换器对应的类就是RegexConverter class RegexConverter(BaseConverter): """ 自定义URL匹配正则表达式 """ def __init__(self, map, regex):# 参数regex接收传过来的nid参数 super(RegexConverter, self).__init__(map) self.regex = regex def 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 :param value: :return: """ 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 :param value: :return: """ val = super(RegexConverter, self).to_url(value) return val app.url_map.converters['xxx'] = RegexConverter @app.route('/index/<xxx("\d+"):nid>',methods=['GET','POST']) # 定义好转换器之后,就这样写了。 def index(nid): print(nid,type(nid)) v = url_for('index',nid=999) # /index/999 print(v) return "Index"
添加路由的两种方式
# 路由方式一(*): @app.route('/index',methods=['GET','POST']) def index(): return "Index" # 路由方式二: def order(): return 'Order' app.add_url_rule('/order',view_func=order)
反向生成url
@app.route('/index',methods=['GET','POST'],endpoint='n1') # endpoint 给路由起别名。如果不起别名,就用函数名 def index(): v1 = url_for('n1') v2 = url_for('login') # url_for 反向生成url v3 = url_for('logout') print(v1,v2,v3) return "Index" @app.route('/login',methods=['GET','POST']) def login(): return "login" @app.route('/logout',methods=['GET','POST']) def logout(): return "logout"
四、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,如:
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<!DOCTYPE html> <html> <head lang="en"> <meta charset="UTF-8"> <title></title> </head> <body> <h1>自定义函数</h1> {{ww()|safe}} </body> </html>
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#!/usr/bin/env python # -*- coding:utf-8 -*- from flask import Flask,render_template app = Flask(__name__) def wupeiqi(): return '<h1>Wupeiqi</h1>' @app.route('/login', methods=['GET', 'POST']) def login(): return render_template('login.html', ww=wupeiqi) app.run()
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<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> {% macro input(name, type='text', value='') %} <input type="{{ type }}" name="{{ name }}" value="{{ value }}"> {% endmacro %} {{ input('n1') }} {% include 'tp.html' %} <h1>asdf{{ v.k1}}</h1> </body> </html>
注意:Markup等价django的mark_safe
五、请求和响应
from flask import Flask from flask import request from flask import render_template from flask import redirect from flask import make_response app = Flask(__name__) @app.route('/login.html', methods=['GET', "POST"]) def login(): # 请求相关信息 # request.method 请求的方法 # request.args 获取GET请求的内容 # request.args.get("id") 获取id的值 # request.args。getlist('ids') 获取多个值 # data = request.args # data_dict = data.to_dict() 通过to_dict()方法转化成字典 # request.remote_addr 获取ip # request.form 获取POST请求的值,获取form表单里面的内容 # request.values 所有的请求参数 # request.cookies 获取cookies # request.headers 获取headers信息,是个list # request.path 仅获取端口号和参数中间的路由 /testrequest # request.full_path # request.script_root 什么都没获取到 # request.url 获取完整的url,带参数 http://192.168.1.183:5000/testrequest?a&b # request.base_url 获取除参数外的url部分 http://192.168.1.183:5000/testrequest # request.url_root 仅获取地址和端口号 http://192.168.1.183:5000/ # request.host_url # request.host # request.files 随请求上传的文件 # obj = request.files['the_file_name'] # obj.save('/var/www/uploads/' + secure_filename(f.filename)) # request.data 是请求的数据 # 响应相关信息 # return "字符串" 实际上是调用make_response # return render_template('html模板路径',**{}) **{'obj':obj}形式 # return render_template('html模板路径',obj=obj) # return redirect('/index.html') # return jsonify(**{'obj':obj}) 返回json数据 from flask import jsonify # 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 response return "内容" if __name__ == '__main__': app.run()
六、Session
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)
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from flask import Flask, session, redirect, url_for, escape, request app = Flask(__name__) @app.route('/') def index(): if 'username' in session: return 'Logged in as %s' % escape(session['username']) return 'You are not logged in' @app.route('/login', methods=['GET', 'POST']) def login(): if request.method == 'POST': session['username'] = request.form['username'] return redirect(url_for('index')) return ''' <form action="" method="post"> <p><input type=text name=username> <p><input type=submit value=Login> </form> ''' @app.route('/logout') def logout(): # remove the username from the session if it's there session.pop('username', None) return redirect(url_for('index')) # set the secret key. keep this really secret: app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
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pip3 install Flask-Session run.py from flask import Flask from flask import session from pro_flask.utils.session import MySessionInterface app = Flask(__name__) app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT' app.session_interface = MySessionInterface() @app.route('/login.html', methods=['GET', "POST"]) def login(): print(session) session['user1'] = 'alex' session['user2'] = 'alex' del session['user2'] return "内容" if __name__ == '__main__': app.run() session.py #!/usr/bin/env python # -*- coding:utf-8 -*- import uuid import json from flask.sessions import SessionInterface from flask.sessions import SessionMixin from itsdangerous import Signer, BadSignature, want_bytes class MySession(dict, SessionMixin): def __init__(self, initial=None, sid=None): self.sid = sid self.initial = initial super(MySession, self).__init__(initial or ()) def __setitem__(self, key, value): super(MySession, self).__setitem__(key, value) def __getitem__(self, item): return super(MySession, self).__getitem__(item) def __delitem__(self, key): super(MySession, self).__delitem__(key) class MySessionInterface(SessionInterface): session_class = MySession container = {} def __init__(self): import redis self.redis = redis.Redis() def _generate_sid(self): return str(uuid.uuid4()) def _get_signer(self, app): if not app.secret_key: return None return Signer(app.secret_key, salt='flask-session', key_derivation='hmac') def open_session(self, app, request): """ 程序刚启动时执行,需要返回一个session对象 """ sid = request.cookies.get(app.session_cookie_name) if not sid: sid = self._generate_sid() return self.session_class(sid=sid) signer = self._get_signer(app) try: sid_as_bytes = signer.unsign(sid) sid = sid_as_bytes.decode() except BadSignature: sid = self._generate_sid() return self.session_class(sid=sid) # session保存在redis中 # val = self.redis.get(sid) # session保存在内存中 val = self.container.get(sid) if val is not None: try: data = json.loads(val) return self.session_class(data, sid=sid) except: return self.session_class(sid=sid) return self.session_class(sid=sid) def save_session(self, app, session, response): """ 程序结束前执行,可以保存session中所有的值 如: 保存到resit 写入到用户cookie """ domain = self.get_cookie_domain(app) path = self.get_cookie_path(app) httponly = self.get_cookie_httponly(app) secure = self.get_cookie_secure(app) expires = self.get_expiration_time(app, session) val = json.dumps(dict(session)) # session保存在redis中 # self.redis.setex(name=session.sid, value=val, time=app.permanent_session_lifetime) # session保存在内存中 self.container.setdefault(session.sid, val) session_id = self._get_signer(app).sign(want_bytes(session.sid)) response.set_cookie(app.session_cookie_name, session_id, expires=expires, httponly=httponly, domain=domain, path=path, secure=secure)
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#!/usr/bin/env python # -*- coding:utf-8 -*- """ pip3 install redis pip3 install flask-session """ from flask import Flask, session, redirect from flask.ext.session import Session app = Flask(__name__) app.debug = True app.secret_key = 'asdfasdfasd' app.config['SESSION_TYPE'] = 'redis' from redis import Redis app.config['SESSION_REDIS'] = Redis(host='192.168.0.94',port='6379') Session(app) @app.route('/login') def login(): session['username'] = 'alex' return redirect('/index') @app.route('/index') def index(): name = session['username'] return name if __name__ == '__main__': app.run()
七、蓝图
蓝图用于为应用提供目录划分:
小型应用程序:示例
大型应用程序:示例
其他:
- 蓝图URL前缀:xxx = Blueprint('account', __name__,url_prefix='/xxx')
- 蓝图子域名:xxx = Blueprint('account', __name__,subdomain='admin')
# 前提需要给配置SERVER_NAME: app.config['SERVER_NAME'] = 'wupeiqi.com:5000'
# 访问时:admin.wupeiqi.com:5000/login.html
八、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。闪现
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from flask import Flask, flash, redirect, render_template, request, get_flashed_messages app = Flask(__name__) app.secret_key = 'some_secret' @app.route('/') def index1(): messages = get_flashed_messages() print(messages) return "Index1" @app.route('/set') def index2(): v = request.args.get('p') flash(v) return 'ok' if __name__ == "__main__": app.run()
九、中间件
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from flask import Flask, flash, redirect, render_template, request app = Flask(__name__) app.secret_key = 'some_secret' @app.route('/') def index1(): return render_template('index.html') @app.route('/set') def index2(): v = request.args.get('p') flash(v) return 'ok' class MiddleWare: def __init__(self,wsgi_app): self.wsgi_app = wsgi_app def __call__(self, *args, **kwargs): return self.wsgi_app(*args, **kwargs) if __name__ == "__main__": app.wsgi_app = MiddleWare(app.wsgi_app) app.run(port=9999)
十、请求扩展
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#!/usr/bin/env python # -*- coding:utf-8 -*- from flask import Flask, Request, render_template app = Flask(__name__, template_folder='templates') app.debug = True @app.before_first_request def before_first_request1(): print('before_first_request1') @app.before_first_request def before_first_request2(): print('before_first_request2') @app.before_request def before_request1(): Request.nnn = 123 print('before_request1') @app.before_request def before_request2(): print('before_request2') @app.after_request def after_request1(response): print('before_request1', response) return response @app.after_request def after_request2(response): print('before_request2', response) return response @app.errorhandler(404) def page_not_found(error): return 'This page does not exist', 404 @app.template_global() def sb(a1, a2): return a1 + a2 @app.template_filter() def db(a1, a2, a3): return a1 + a2 + a3 @app.route('/') def hello_world(): return render_template('hello.html') if __name__ == '__main__': app.run()
调用方式:{{sb(1,2)}} {{ 1|db(2,3)}}
十一、Flask插件
- WTForms
- SQLAchemy
- 等... http://flask.pocoo.org/extensions/
补充:
pip install pipreqs
安装这个模块之后项目里会自动生成一个requirements.txt文件,里面显示的是这个项目安装的模块及其版本信息。
生成依赖文件requirements.txt 命令: pipreqs ./ (./表示当前文件)
安装依赖文件requirements.txt 命令: pip install -r requirements.txt