Flask

時間 2019-11-18

標籤 flask 欄目 Python 简体版

原文原文鏈接

Flask是一個基於Python開發而且依賴jinja2模板和Werkzeug WSGI服務的一個微型框架，對於Werkzeug本質是Socket服務端，其用於接收http請求並對請求進行預處理，而後觸發Flask框架，開發人員基於Flask框架提供的功能對請求進行相應的處理，並返回給用戶，若是要返回給用戶複雜的內容時，須要藉助jinja2模板來實現對模板的處理，即：將模板和數據進行渲染，將渲染後的字符串返回給用戶瀏覽器。html

談談python，web框架

django框架：大而全，內部提供：ORM、Admin、中間件、From、ModelForm、Sessssion、rest_frmarword、緩存、信號、CSRF等
flask框架： 小而精，可擴展性強，第三方組件豐富（django中的幾乎都有）
tornado框架：小而精，實現異步非阻塞
其餘框架：
　　　　web.py
　　　　bottle.py

a. django和flask都依賴wsgi
- django 依賴 wsgiref
- flask 依賴 werkzeugpython

基本使用：

from werkzeug.wrappers import Response,Request
from werkzeug.serving import run_simple

@Request.application
def index(request):
    return Response("hello world")

if __name__ == '__main__':
    run_simple("localhost",4000,index)

werkzeug

from flask import Flask
app=Flask(__name__)  #Flask類對象

@app.route('/index')
def index():
    return "hello world"

if __name__ == '__main__':
    app.run()

練習：mysql

from flask import Flask,Response,render_template,request,redirect,session

api=Flask("__name__")

# 由於是將session寫入到cookie中，必須加密(密鑰)
api.secret_key="kjabbgajdvv"

USER_INFO={
    "1":{"name":"曹超","age":18},
    "2":{"name":"曹大超","age":28},
    "3":{"name":"曹小超","age":38}
}


@api.route("/login",methods=["GET","POST"])
def login():
    if request.method=="POST":
        # post請求（request.values==request.body）
        user=request.form.get("user")
        pwd=request.form.get("pwd")
        if user=="cao"and pwd=="123":
            # 將user寫如seesion中
            session["user_info"]=user
            return redirect("index")

    return render_template('login.html')


@api.route("/index")
def index():
    user=session.get("user_info")
    if not user:
        return redirect("login")
    return render_template("index.html" ,user_dict=USER_INFO)  #模板中取k,v時須要items()
    # return render_template("index.html" ,**{"user_dict":USER_INFO})

@api.route("/detail")
def detail():
    user = session.get("user_info")
    if not user:
        return redirect("login")
    # get請求
    uid=request.args.get("uid")

    user_info=USER_INFO[uid]
    return render_template("detail.html" ,user_info=user_info)

@api.route("/logout")
def logout():
    # 刪除session
    del session["user_info"]
    return redirect("login")


if __name__ == '__main__':
    api.run(port=8080,debug=True)

路由系統

@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'])

兩種路由寫法：web

方法一：
@app.route("/index")
def index():
    return "index"

方法二：
def login():

    return "login"

app.add_url_rule('/login',"xx",login)  #xx 別名

或app.add_url_rule('/login',view_func=login)

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參數：
            rule,                       URL規則
            view_func,                  視圖函數名稱
            defaults=None,              默認值,當URL中無參數，函數須要參數時，使用defaults={'k':'v'}爲函數提供參數
            endpoint=None,              名稱，用於反向生成URL，即： url_for('名稱')
            methods=None,               容許的請求方式，如：["GET","POST"]
            

            strict_slashes=None,        對URL最後的 / 符號是否嚴格要求，
                                        如：
                                            @app.route('/index',strict_slashes=False)，
                                                訪問 http://www.xx.com/index/ 或 http://www.xx.com/index都可
                                            @app.route('/index',strict_slashes=True)
                                                僅訪問 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,             子域名訪問
                                                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()

註冊路由原理

from flask import Flask, views, url_for
            from werkzeug.routing import BaseConverter

            app = Flask(import_name=__name__)


            class RegexConverter(BaseConverter):
                """
                自定義URL匹配正則表達式
                """
                def __init__(self, map, regex):
                    super(RegexConverter, self).__init__(map)
                    self.regex = regex

                def to_python(self, value):
                    """
                    路由匹配時，匹配成功後傳遞給視圖函數中參數的值
                    :param value: 
                    :return: 
                    """
                    return int(value)

                def to_url(self, value):
                    """
                    使用url_for反向生成URL時，傳遞的參數通過該方法處理，返回的值用於生成URL中的參數
                    :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()

自定製正則路由匹配

配置文件

flask中的配置文件是一個flask.config.Config對象（繼承字典）,默認配置爲：
    {
        'DEBUG':                                get_debug_flag(default=False),  是否開啓Debug模式
        'TESTING':                              False,                          是否開啓測試模式
        '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： 因爲Config對象本質上是字典，因此還可使用app.config.update(...)
 
方式二：
    app.config.from_pyfile("python文件名稱")
        如：
            settings.py
                DEBUG = True
 
            app.config.from_pyfile("settings.py")
 
    app.config.from_envvar("環境變量名稱")
        環境變量的值爲python文件名稱名稱，內部調用from_pyfile方法
 
 
    app.config.from_json("json文件名稱")
        JSON文件名稱，必須是json格式，由於內部會執行json.loads
 
    app.config.from_mapping({'DEBUG':True})
        字典格式
 
    app.config.from_object("python類或類的路徑")
 
        app.config.from_object('pro_flask.settings.TestingConfig')
 
        settings.py
 
            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
 
        PS: 從sys.path中已經存在路徑開始寫
     
 
    PS: settings.py文件默認路徑要放在程序root_path目錄，若是instance_relative_config爲True，則就是instance_path目錄

View Code

練習正則表達式

from flask import Flask,session

app=Flask(__name__)
app.config.from_object("settings.DevelopmentConfig")

@app.route("/index")
def index():
    session["user"]=123
    return "index"


def login():
    print(session["user"])
    return "login"

app.add_url_rule('/login',view_func=login)


if __name__ == '__main__':
    app.run()

View.py

class BaseConfig(object):
    DEBUG = True
    SECRET_KEY = "asudflkjdfadjfakdf"


class ProductionConfig(BaseConfig):
    DEBUG = False


class DevelopmentConfig(BaseConfig):
    pass


class TestingConfig(BaseConfig):
    pass

settings.py

視圖

CBV：

from flask import Flask,render_template,redirect,views
app = Flask(__name__)


def wapper(func):
    def inner(*args,**kwargs):
        print('before')
        return func(*args,**kwargs)
    return inner


class IndexView(views.MethodView):
    methods = ['GET']
    decorators = [wapper, ]  #裝飾器

    def get(self):
        return 'Index.GET'
    def post(self):
        return 'Index.POST'

app.add_url_rule('/index', view_func=IndexView.as_view(name='index'))  # 別名name=endpoint

if __name__ == '__main__':
    app.run()

session

session 對象。它容許你在不一樣請求間存儲特定用戶的信息。它是在 Cookies 的基礎上實現的，而且對 Cookies 進行密鑰簽名要使用會話，你須要設置一個密鑰。redis

設置：session['username'] ＝ 'xxx'sql
刪除：session.pop('username', None)

方法和字典同樣django

注意：session中存儲的是字典，修改字典內部元素時，會形成數據不更新。
           - motified = True
           - SESSION_REFRESH_EACH_REQUEST = True and  session.permanent = True(redis中默認)

from flask import Flask,session
from flask_session import RedisSessionInterface
app = Flask(__name__)
app.secret_key = 'asdf'

# 默認session
# from flask.sessions import SecureCookieSessionInterface
# app.session_interface = SecureCookieSessionInterface()

# 方式一：redis 保存session
# from redis import Redis
# app.session_interface = RedisSessionInterface(
#     redis=Redis(host='127.0.0.1',port=6379),
#     key_prefix='flaskxxx'
# )

# 方式二：redis 保存session   見第三方session
from flask.ext.session import Session
from redis import Redis
app.config['SESSION_TYPE'] = 'redis'
app.config['SESSION_REDIS'] = Redis(host='192.168.0.94',port='6379')
Session(app)


@app.route('/login')
def login():
    session['k1'] = 123
    return 'login'

@app.route('/xx')
def index():
    v = session['k1']
    print(v)
    return 'Index'

if __name__ == '__main__':
 
    app.run()

基本使用

#!/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()

第三方session

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 "內容"

            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):
                    """
                    程序剛啓動時執行，須要返回一個session對象
                    """
                    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保存在內存中
                    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):
                    """
                    程序結束前執行，能夠保存session中全部的值
                    如：
                        保存到resit
                        寫入到用戶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保存在內存中
                    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)

自定義Session

模板

Flask使用的是Jinja2模板，因此其語法(更接近python)和Django無差異json

view.py

from flask import Flask,session,render_template,Markup

app=Flask(__name__)
app.debug=True

def func1():
    return 22

def func2():
    return Markup("<input value='姓名'/>")

#全局定義函數，全部模板均可以用
@app.template_global()
def func3(a1,a2):
    return a1+a2


@app.route("/index")
def index():
    data_dict={
        "k1":"caohcoa",
        "k2":[11,22,33,44,550],
        "k5":{"name":"sb","age":23},
        "k3":lambda x:x+1,
        "k4":func1,
        "k6":func2
    }
    return render_template("index.html",**data_dict)


if __name__ == '__main__':
    app.run()

templates-->index.htmlflask

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Title</title>

</head>
<body>

<h3>INDEX</h3>
<div>
    <h4>{{k1}}</h4>
    <h4>{{k2.0}}  {{k2[0]}} </h4>
    <h4>{{k3(3)}}</h4>
    <h4>{{k4()}}</h4>
    <h4>{{k5["name"]}}  {{k5.name}} {{k5.get("name")}}</h4>
    <h4>{{k6()}} </h4>
    <h4>{{func3(1,3)}} </h4>
</div>

</body>
</html>

防止XSS攻擊

模板： xx|safe
腳本：Markup(xxx)

請求與響應

# 請求相關信息
        # 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))

        # 響應相關信息
        # return "字符串"
        # return render_template('html模板路徑',**{})
        # return redirect('/index.html')

        # response = make_response(render_template('index.html'))
        # response是flask.wrappers.Response類型
        # response.delete_cookie('key')
        # response.set_cookie('key', 'value')
        # response.headers['X-Something'] = 'A value'
        # return response

View Code

特殊裝飾器

條件：當請求到來時，在函數執行以前和函數執行以後進行操做

一、使用裝飾器

from flask import Flask,Response,render_template,request,redirect,session

api=Flask("__name__")

# 由於是將session寫入到cookie中，必須加密
api.secret_key="kjabbgajdvv"

USER_INFO={
    "1":{"name":"曹超","age":18},
    "2":{"name":"曹大超","age":28},
    "3":{"name":"曹小超","age":38}
}

def wrapper(func):
    def inner(*args,**kwargs):
        user=session.get("user_info")
        if not user:
            return redirect("login")
        ret=func(*args,**kwargs)
        return ret
    return inner


@api.route("/login",methods=["GET","POST"])
def login():
    if request.method=="POST":
        # post請求（request.values==request.body）
        user=request.form.get("user")
        pwd=request.form.get("pwd")
        if user=="cao"and pwd=="123":
            # 將user寫如seesion中
            session["user_info"]=user
            return redirect("index")

    return render_template('login.html')


@api.route("/index",endpoint="index")
#一、執行wrapper函數 wrapper(index)
#二、將第一步的返回值從新賦值 index=wrapper(index)
@wrapper   #index=wrapper(index)
def index():
    return render_template("index.html" ,user_dict=USER_INFO)


@api.route("/detail",endpoint="detail")  #endpoint  別名
@wrapper
def detail():
    # get請求
    uid=request.args.get("uid")
    user_info=USER_INFO[uid]

    return render_template("detail.html" ,user_info=user_info)

@api.route("/logout")
def logout():
    # 刪除session
    del session["user_info"]
    return redirect("login")


if __name__ == '__main__':
    api.run(port=8080,debug=True)

二、使用before_request和after_request相似於中間件

搜索

from flask import Flask
app=Flask(__name__) @app.before_request def x1(): print("前1") @app.before_request def x2(): print("前2") @app.after_request def o1(response): print("後1") return response @app.after_request def o2(response): print("後2") return response @app.route("/index") def index(): print("index") return "index" if __name__ == '__main__': app.run()

結果

流程圖：

利用此功能作登陸認證：

from flask import Flask,render_template,redirect,request,session
app = Flask(__name__)
app.secret_key = 'asdfasdfasdf'
@app.before_request
def check_login():
    if request.path == '/login':
        return None
    user = session.get('user_info')
    if not user:
        return redirect('/login')

@app.route('/login',methods=['GET','POST'])
def login():
    return "視圖函數x1"

@app.route('/index',methods=['GET','POST'])
def index():
    print('視圖函數x2')
    return "視圖函數x2"

if __name__ == '__main__':
    app.run()

message(閃現)

message是一個基於Session（先將數據寫入session，在session.pop("xx")）實現的用於保存數據的集合，其特色是：使用一次就刪除。

from flask import Flask,flash,get_flashed_messages

app=Flask(__name__)
app.secret_key="sb"

@app.route("/login")
def login():
    flash("你好啊！",category="x1")
    return "login"

@app.route("/index")
def index():
    data=get_flashed_messages(category_filter=['x1'])
    print(data)
    return "index"

if __name__=="__main__":
    app.run()

View Code

中間件

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)

View Code

藍圖（Blueprint）

做用：一、目錄結構劃分

　　　二、一類 URL的劃分

　　　三、基於before_request(裝飾器)現實一類url的功能

藍圖用於爲應用提供目錄劃分：

小型應用程序：

# 啓動文件
from blueprint.flaskitem import app

if __name__ == '__main__':
    app.run()

manage.py

from flask import Flask

app=Flask(__name__)

from .views import user,course

app.register_blueprint(user.us)
app.register_blueprint(course.co)

__init__.py

from flask import Blueprint

# 示例化藍圖
co=Blueprint("co",__name__)

@co.route("/index")
def index():
    return "index"

@co.route("/login")
def login():
    return "login"

course.py

from flask import Blueprint

# 示例化藍圖
us=Blueprint("us",__name__,url_prefix="api") #url_prefix ,訪問url時加上api前綴

@us.route("/info")
def info():
    return "info"

@us.route("/loginout")
def loginout():
    return "loginout"

user.py

大型應用程序：

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