flask快速入门
1.1.三种框架比较
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,是基于装饰器来实现,但是本质还是通过add_url_rule来实现的
Tornado:异步非阻塞
1.2.安装和运行
(1)安装
创建虚拟环境,然后直接安装
mkvirtualenv flask_project
pip install -i https://pypi.douban.com/simple flask
(2)运行
基本使用
from flask import Flask #实例化flask对象 app = Flask(__name__) #将'/'和函数index的对应关系加到路由中 @app.route('/') def index(): return 'Hello World!' if __name__ == '__main__': #监听用户请求 #如果有用户请求到来,则执行app的__call__方法,app.__call__ app.run()
浏览器访问:http://127.0.0.1:5000/
1.3.快速入门实例
(1)view.py
from flask import Flask,render_template,request,redirect,session,url_for app = Flask(__name__) app.debug = True
app.secret_key = 'abcdef' USERS = { 1:{'name':'derek','age':18}, 2:{'name':'tom','age':20}, 3:{'name':'jack','age':22}, } @app.route('/detail/<int:nid>',methods=['GET']) def detail(nid): # 没登录不能访问 user = session.get('user_info') if not user: return redirect('/login') info = USERS.get(nid) return render_template('detail.html',info=info) @app.route('/index',methods=['GET']) def index(): #没登录不能访问 user = session.get('user_info') if not user: # return redirect('/login') #根据设置的别名反向生成url url = url_for('login11') return redirect(url) return render_template('index.html',user_dict=USERS) @app.route('/login',methods=['GET','POST'],endpoint='login11') #endpoint起别名 def login(): if request.method == 'GET': return render_template('login.html') else: user = request.form.get('user') pwd = request.form.get('pwd') if user == 'derek' and pwd == '123': #添加session值 user = session['user_info'] = user return redirect('/index') return render_template('login.html',error='用户名或密码错误') if __name__ == '__main__': app.run()
(2)templates/login.html
<h1>用户登录</h1> <form method="post"> <input type="text" name="user"> <input type="text" name="pwd"> <input type="submit" value="登录"> {{error}} </form>
(3)templates/index.html
<h1>用户登录</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>
(4)templates/detail.html
{{info.name}}
{{info.age}}
1.4.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, }
(1)方式一
app.debug = True
(2)方式二
app.config['DEBUG'] = True
(3)方式三(最常用)
app.config.from_object("settings.DevelopmentConfig")
settings.py
一个父类,其它子类继承,重写父类的某个方法
class Config(object): DEBUG = False TESTING = False DATABASE_URI = 'sqlite://:memory:' class ProductionConfig(Config): DATABASE_URI = 'mysql://user@localhost/foo' class DevelopmentConfig(Config): DEBUG = True class TestingConfig(Config): TESTING = True
1.5.路由系统本质
(1)常用路由系统有以下五种
@app.route('/user/<username>') @app.route('/post/<int:post_id>') @app.route('/post/<float:post_id>') @app.route('/post/<path:path>') @app.route('/login', methods=['GET', 'POST'])
基本上这五种方式满足大多数需求,还可以自定制正则路由
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() b. 自定制正则路由匹配
(2)路由系统的本质
from flask import Flask,render_template,request,redirect,session,url_for app = Flask(__name__) app.debug = True app.secret_key = 'abcdef' #源码分析 ''' 路由本质,通过看源码分析得出,其本质是通过add_url_rule来实现的 1.decorator = app.route('/',methods=['GET','POST'],endpoint='index') def route(self, rule, **options): #app对象(即self) #rule=/ #option = methods=['GET','POST'],endpoint='index' def decorator(f): endpoint = options.pop('endpoint', None) self.add_url_rule(rule, endpoint, f, **options) return f return decorator 2.@decorator decorator(index) ''' @app.route('/',methods=['GET','POST'],endpoint='index') def index(): return 'Hello word' def login(): return '登录' #通过分析源码,路由可以用下面这种方式实现 app.add_url_rule('/login','login11',login,methods=['GET','POST'],) #第二个参数是别名,第三个参数是视图函数,如果endpoint不写,则默认endpoint='视图函数名' if __name__ == '__main__': app.run()
1.6.flask之CBV
from flask import Flask,render_template,request,redirect,session,url_for,views app = Flask(__name__) app.debug = True app.secret_key = 'abcdef' def auth(func): def inner(*args, **kwargs): result = func(*args, **kwargs) return result return inner 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 if __name__ == '__main__': app.run()
1.7.add_url_role参数介绍
@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()
(1)最基本的url几种方式
from flask import Flask,views app = Flask(__name__) app.debug = True app.secret_key = 'abcdef' #第一种 @app.route('/',methods=['GET','POST'],endpoint='index') def index(): return 'Hello World!' def login(): return '登录' #第二种 app.add_url_rule('/login','login',login,methods=['GET','POST']) def auth(func): def inner(*args, **kwargs): result = func(*args, **kwargs) return result return inner #CBV的模式 class DetailView(views.MethodView): methods = ['GET'] decorators = [auth, ] def get(self): return 'Detail.GET' def post(self): return 'Detail.POST' #第三种 app.add_url_rule('/detail', view_func=DetailView.as_view(name='detail')) # name=endpoint if __name__ == '__main__': app.run()
(2)参数defaults
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
(3)参数strict_slashes=None
#对URL最后的 / 符号是否严格要求,默认为False,如: @app.route('/index', strict_slashes=False) #下面两种方式都可以访问 http: // www.xx.com / index / http: // www.xx.com / index #如果设为True @app.route('/index', strict_slashes=True) #只能这样访问 http: // www.xx.com / index
(4)redirect_to=None
重定向到指定地址
@app.route('/index',methods=['GET','POST'],endpoint='index1',redirect_to="/index2") def index(): return '公司旧网页' @app.route('/index2',methods=['GET','POST'],endpoint='index2',) def index(): return '公司新网页'
访问:http://127.0.0.1:5000/index会直接重定向到http://127.0.0.1:5000/index2
1.8.模板语言
flask的模板语法和Django的语法差不多,下面一个简单实例
Markup等价于Django的mark_safe
前端也是用 |safe
from flask import Flask,render_template,Markup app = Flask(__name__) app.debug = True app.secret_key = 'abcdef' def func1(arg): return Markup("<input type='text' value='%s' />"%arg) @app.route('/') def index(): return render_template('index.html',func1=func1) if __name__ == '__main__': app.run()
index.html
{{func1('zhang ')}} <!--传参数arg -->
1.9.请求与响应
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 # request.args # request.form # request.values # request.cookies # request.headers # request.path # request.full_path # request.script_root # request.url # request.base_url # request.url_root # request.host_url # request.host # 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') # 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()
1.10.flash介绍
(1)简单使用方法
from flask import Flask,flash,get_flashed_messages app = Flask(__name__) app.debug = True app.secret_key = 'abcdef' @app.route('/get') def get(): data = get_flashed_messages() print(data) return 'hello world' @app.route('/set') def set(): #向某个地方设置一个值 flash('访问一次就设置一次') return 'hello world' if __name__ == '__main__': app.run()
访问:http://127.0.0.1:5000/set 访问一个就会设置一次值
访问:http://127.0.0.1:5000/get 从某个地方获取所有的值,并清除