Flask

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

　　

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、基本操作

from flask import Flask

app = Flask(__name__)

 
@app.route('/')

def hello_world():

    return 'Hello World!'


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")
 
        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: 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>')
• @app.route('/post/<int:post_id>')
• @app.route('/post/<float:post_id>')
• @app.route('/post/<path:path>')
• @app.route('/login', methods=['GET', 'POST'])

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：

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()
        

@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("namic", subdomain="<username>")
                                        def username_index(username):
                                            """Dynamic subdomains are also supported
                                            Try going to user1.your-domain.tldnamic"""
                                            return username + ".your-domain.tld"
    
    
                                        if __name__ == '__main__':
                                            app.run()

 class IndexView(views.View):   # 方式一：CBV
    methods = ['GET']
    decorators = [wapper, ]

    def dispatch_request(self):
        print('Index')
        return 'Index!'


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

class IndexView(views.MethodView):   #方式二：CBV 该方法更方便
    methods = ['GET']
    decorators = [wapper, ]

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

    def post(self):
        return

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

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()

自定义路由转换器

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

app = Flask(__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 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'],endpoint='n1')
def index(nid):   # index提供一个数字，数字自动传给nid uuid主板根据当前时间计算出唯一的标识（可能重复，几率很小）
    url_for('index', nid=999)   # /index/999   生成前先执行to_url
    return "Index"


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

添加路由的两种方式

from flask import Flask, render_template, redirect

app = Flask(__name__)

'''
1.执行decorator = app.route('/index',methods=['GET', 'POST'])
2.@decorator
    -新index = decorator(index)
'''
# 路由方式一（推荐）
@app.route('/index',methods=['GET', 'POST'])
def index():
    return "index"

# 添加路由方式二（本质）
def order():
    return 'order'

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


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

四、 反向生成URL

from flask import Flask, url_for

app = Flask(__name__)


@app.route('/index',methods=['GET', 'POST'],endpoint='n1')
def index():
    v1 = url_for('n1')   # 创建别名，用于反向生成才起别名。不起名别就是其函数名
    v2 = url_for('n2')
    v3 = url_for("n3")
    print(v1,v2,v3)
    return "Index"

@app.route('/login',methods=['GET', 'POST'],endpoint='n2')
def login():
    return "Login"

@app.route('/logout',methods=['GET', 'POST'],endpoint='n3')
def logout():
    v3 = url_for("n3")
    print(v3)
    return "Logout"


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

五、视图中添加装饰器

from flask import Flask, url_for
import functools

app = Flask(__name__)


def wapper(func):
    @functools.wraps(func)
    def inner(*args, **kwargs):
        print('before')
        return func(*args, **kwargs)

    return inner


@app.route('/index', methods=['GET', 'POST'])
@wapper
def index():
    return "Index"


@app.route('/order', methods=['GET', 'POST'])
@wapper
def order():
    return "Order"


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

 六、请求与响应

from flask import Flask, render_template, redirect, request, jsonify, make_response
app= Flask(__name__)

@app.route('/index', methods=['POST', 'GET'])
def index():
    # 请求相关
    # request.method
    # request.args
    # request.form
    # request.cookies
    # request.headers
    # request.path
    # request.files
    # obj = request.files['the_file_name']
    # obj.save('ar/www/uploads/' + secure_filename(f.filename))

    # 不常用
    # request.values
    # request.full_path
    # request.script_root
    # request.url
    # request.base_url
    # request.url_root
    # request.host_url
    # request.host


    # 响应相关
    # return json.dumps({})  # return jsonify({})
    return "字符串"
    # return render_template('html模板路径',**{})
    # return redirect('/index.html')

    # 设置cookie
    # 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


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

七、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

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：

<!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>

#!/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()

<!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>

from flask import Flask, render_template, redirect, Markup

app = Flask(__name__)


@app.template_global()
def sbb(a1, a2):
    """
    每个模板都可以使用
    :param a1:
    :param a2:
    :return:
    """
    return a1 + a2


def gen_input(value):
    # return "<input value='%s'/>" %value   # 防止xss攻击
    return Markup("<input value='%s'/>" % value)


@app.route('/index', methods=['GET', 'POST'])
def index():
    context = {
        'k1': 123,
        'k2': [11, 22, 33],
        'k3': {'name': 'oldboy', 'age': '123'},
        'k4': lambda x: x + 1,  # 函数不直接执行
        'k5': gen_input  # 只有当前模板才能调用的函数
    }

    return render_template('/index.html', **context)


@app.route('/index', methods=['POST', 'GET'])
def order():
    context = {
        'k1': 123,
        'k2': [11, 22, 33],
    }

    return render_template('order.html', **context)


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

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div>头部</div>
    <div>
        {% block content %} {% endblock %}
    </div>
    <div>底部</div>
</body>
<html>

{% extends 'layout.html' %}
{% block content %}
    <h1>{{k1}}</h1>
    <h1>{{k2.0}}  {{k2[0]}}</h1>
    <h1>{{k3.name}}  {{k3['name']}}  {{k3.get('name',888}}</h1>
    <h1>{{k4(66)}}</h1>
    <h1>{{k5(99)|safe}}</h1>
    <h1>{{k5(99)}}</h1>
    <h1>{{sbb(1,2)}}</h1>
{% endblock %}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>{{k1}}</h1>
    <h1>{{k2.0}}  {{k2[0]}}</h1>
    <h1>{{k3.name}}  {{k3['name']}}  {{k3.get('name',888}}</h1>
    <h1>{{k4(66)}}</h1>
    <h1>{{k5(99)|safe}}</h1>
    <h1>{{k5(99)}}</h1>
    <h1>{{sbb(1,2)}}</h1>
</body>
<html>

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <h1>{{sbb(1,2)}}</h1>
</body>
<html>

八、请求扩展

#!/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)}}

九、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)

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'

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)

#!/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()

十、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

十一、闪现

from flask import Flask, session,flash,get_flashed_messages

app = Flask(__name__)
app.secret_key = 'adacdnduaihu'


@app.route('/login', methods=['POST', 'GET'])
def login():
    flash('内容的',category='x1')   # 设置一个值 category='x1'分类
    flash('内容的', category='x2')  # 设置一个值
    return '视图函数x1'


@app.route('/index', methods=['POST', 'GET'])
def index():
    data = get_flashed_messages(category_filter=['x1'])  # 取值
    data = get_flashed_messages()
    print(data)
    return '视图函数x2'

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

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

十二、中间件

from flask import Flask, session

app = Flask(__name__)
app.secret_key = 'adacdnduaihu'


@app.route('/index', methods=['POST', 'GET'])
def index():
    return '视图函数'


class Middleware(object):
    def __init__(self, old_wsgi_app):
        """
        服务端启动时，自动执行
        :param old_wsgi_app: 
        """
        self.old_wsgi_app = old_wsgi_app

    def __call__(self, *args, **kwargs):
        """
        每次有用户请求到来时，执行
        :param args:  # environ
        :param kwargs:  # start_response
        :return: 
        """
        print('before')
        obj = self.old_wsgi_app(*args, **kwargs)
        print('after')
        return obj


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

'''
当请求一到来：
1、执行app.__call__
2、再调用app.wsgi_app方法
'''

十三、FLASK插件

• WTForms    
• SQLAchemy
• 等...    http://flask.pocoo.org/extensions/