Flask 的系统学习

详细看地址：

http://www.cnblogs.com/wupeiqi/articles/7552008.html

一. 说明

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)

werkzeug

一. 基本使用

 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'])  # 带参数的装饰器

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：

DEFAULT_CONVERTERS = {
    'default':          UnicodeConverter,
    'string':           UnicodeConverter,
    'any':              AnyConverter,
    'path':             PathConverter,
    'int':              IntegerConverter,
    'float':            FloatConverter,
    'uuid':             UUIDConverter,
}

 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()
         

a.注册路由原理

 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=''))
                 return 'Index'

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

b. 自定制正则路由匹配

四、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>

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()

run.py

<!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>

其他

注意：Markup等价django的mark_safe

五、请求和响应

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()

六、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'

基本使用

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)

自定义Session

#!/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='')
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

七、蓝图

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

八、message

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。

from flask import Flask, flash, redirect, render_template, request, get_flashed_messages

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

        @app.route('/')
        def index1():
            messages = get_flashed_messages()
            print(messages)
            return "Index1"

        @app.route('/set')
        def index2():
            v = request.args.get('p')
            flash(v)
            return 'ok'

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

九、中间件

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)

十、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)}}

十一、Flask插件

WTForms        #类似Django中Form组件
SQLAchemy
等...    http://flask.pocoo.org/extensions/