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  • Flask快速入门

    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,
        }
    flask配置文件

    (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
    自定制正则路由

    (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()
            
    所有参数

    (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()
    请求与响应

    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

     
     
     
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  • 原文地址:https://www.cnblogs.com/gaidy/p/12105657.html
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