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Zhang_derek

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

 

posted on 2018-05-12 13:27 zhang_derek 阅读(...) 评论(...) 编辑 收藏

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