Flask简述

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  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\'])

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\'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
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=\'888\'))
                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

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()
View Code

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

七、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

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()
View Code

九、中间件

from flask import Flask, flash, redirect, render_template, request
 
app = Flask(__name__)
app.secret_key = \'Flask 编写http接口api及接口自动化测试

12_关于flask中的宏

Flask之模板之宏继承包含

Flask模板宏的概念和基本使用

python flask(多对多表查询)

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