Flask 基础知识一

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

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

配置文件整理

外部文件中:k=v k要大写

# NAME='ctz'

# PWD='123'

class BaseConfig(object):

    AA=123456

class TestConfig(BaseConfig):

    DB='127.0.0.1'

class DevConfig(BaseConfig):

    DB='127.0.0.2'

class ProConfig(BaseConfig):

    DB='1270.0.0.3'

from  flask import Flask

import settings

app=Flask(__name__)

#方式一

#app.config['COOK']='ctz'

'''

settings.py

NAME='ctz'

PWD='123'

'''

#方式二

#app.config.from_pyfile('settings.py')

#方式三

# import os

# os.environ['FLASK_SETTING']='settings.py'

# app.config.from_envvar('FLASK_SETTING')

#方式四(推荐使用)

app.config.from_object('settings.DevConfig')

@app.route('/index',methods=['POST','GET'],strict_slashes=False)

def index():

    print(app.config)

    return 'helloworld'

if __name__ == '__main__':

    app.run(debug=True)

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以下对应关系来处理：

DEFAULT_CONVERTERS = {

    'default':          UnicodeConverter,

    'string':           UnicodeConverter,

    'any':              AnyConverter,

    'path':             PathConverter,

    'int':              IntegerConverter,

    'float':            FloatConverter,

    'uuid':             UUIDConverter,

}

四、视图函数

1.fbv

from flask import Flask

# 实例化Flask对象

app = Flask(__name__)

# 生成路由关系，并把关系保存到某个地方,app对象的 url_map字段中

@app.route('/xxxx')  # @decorator

def index():

    return "Index"

if __name__ == '__main__':

    # 启动程序，监听用户请求

    # 一旦请求到来，执行 app.__call__方法

    # 封装用户请求

    # 进行路由匹配

    app.run()

方式1

from flask import Flask

# 实例化Flask对象

app = Flask(__name__)

# def index():

#     return "Index"

# app.add_url_rule('/xxx', "n1", index)

if __name__ == '__main__':

    # 启动程序，监听用户请求

    # 一旦请求到来，执行 app.__call__方法

    # 封装用户请求

    # 进行路由匹配

    app.run()

方式二

简单使用

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

app = Flask(__name__,template_folder='templates',static_url_path='/xxxxxx')

app.secret_key = "sdfasdfasdf3fsdf"

@app.route('/login',methods=['GET',"POST"])

def login():

    if request.method == 'GET':

        return render_template('login.html')

    else:

        user = request.form.get('user')

        pwd = request.form.get('pwd')

        if user == 'alex' and pwd == '':

            session['user_info'] = user

            return redirect('/index')

        else:

            return render_template('login.html',msg='用户名或密码错误')

            # return render_template('login.html',**{'msg':'用户名或密码错误'})

@app.route('/index',methods=['GET'])

def index():

    if not session.get('user_info'):

        return redirect('/login')

    return "欢迎登录"

if __name__ == '__main__':

    app.run()

2.cbv

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

3.@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()

4.自定义正则路由匹配

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

5.和Django比较

Django：

            /index/    func

            /index/    IndexClass.as_view()

        Flask:

            FBV:

                @app.route('/index',endpoint='xx')

                def index(nid):

                    url_for('xx',nid=123)

                    return "Index"

                def index(nid):

                    url_for('xx',nid=123)

                    return "Index"

                app.add_url_rule('/index',index)

            CBV:

                def auth(func):

                    def inner(*args, **kwargs):

                        result = func(*args, **kwargs)

                        return result

                    return inner

                class IndexView(views.MethodView):

                    # methods = ['POST']

                    decorators = [auth,]

                    def get(self):

                        v = url_for('index')

                        print(v)

                        return "GET"

                    def post(self):

                        return "GET"

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

                if __name__ == '__main__':

                    app.run()

五模板

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：

from flask import Flask,url_for,request,redirect,render_template,jsonify,make_response,Markup

from urllib.parse import urlencode,quote,unquote

app = Flask(__name__)

def test(a1,a2):

    return a1+a2

@app.template_global()

def sb(a1,a2):

    return a1 + a2 + 100

@app.template_filter()

def db(a1, a2, a3):

    return a1 + a2 + a3

@app.route('/index',endpoint='xx')

def index():

    v1 = "字符串"

    v2 = [11,22,33]

    v3 = {'k1':'v1','k2':'v2'}

    v4 = Markup("<input type='text' />")

    return render_template('index.html',v1=v1,v2=v2,v3=v3,v4=v4,test=test)

if __name__ == '__main__':

    # app.__call__

    app.run()

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

    <h1>模板</h1>

    {%block body %} {%endblock%}

</body>

</html>

layout.html

{% extends 'layout.html'%}

{%block body %}

    {{v1}}

    <ul>

        {% for item in v2 %}

        <li>{{item}}</li>

        {% endfor %}

    </ul>

    {{v2.1}}

    <ul>

        {% for k,v in v3.items() %}

        <li>{{k}}  {{v}}</li>

        {% endfor %}

    </ul>

    {{v3.k1}}

    {{v3.get('k1')}}

    {{v4}}

    <!--{{v4|safe}}-->

    <h1>{{test(1,19)}}</h1>

    {{sb(1,2)}}

    {{ 1|db(2,3)}}

    {% macro xxxx(name, type='text', value='') %}

        <input type="{{ type }}" name="{{ name }}" value="{{ value }}">

        <input type="{{ type }}" name="{{ name }}" value="{{ value }}">

        <input type="{{ type }}" name="{{ name }}" value="{{ value }}">

        <input type="{{ type }}" name="{{ name }}" value="{{ value }}">

    {% endmacro %}

    {{ xxxx('n1') }}

{%endblock%}

index.html

注意：Markup等价django的mark_safe,函数得带()

六、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()

模仿django的request.GET.urlencode

from flask import Flask,url_for,request,redirect,render_template,jsonify,make_response

from urllib.parse import urlencode,quote,unquote

app = Flask(__name__)

@app.route('/index',endpoint='xx')

def index():

    from werkzeug.datastructures import ImmutableMultiDict

    #模仿django的request.urlencode

    # get_data = request.args

    # get_dict = get_data.to_dict()

    # get_dict['xx'] = '18'

    # url = urlencode(get_dict)

    # print(url)

    # print(request.query_string)

    # print(request.args)

    # val = "%E6%8A%8A%E5%87%A0%E4%B8%AA"

    # print(unquote(val))

    #

    # return "Index"

    # return "Index"

    # return redirect()

    # return render_template()

    # return jsonify(name='alex',age='18')

    response = make_response('xxxxx')

    response.headers['xxx'] = ''

    return response

if __name__ == '__main__':

    # app.__call__

    app.run()

七、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)

方法和字典一样

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

from flask import Flask,session,Session

from urllib.parse import urlencode,quote,unquote

from werkzeug.local import LocalProxy

app = Flask(__name__)

app.secret_key ='sdfsdfsdf'

app.config['SESSION_COOKIE_NAME'] = 'session_lvning'

"""

'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,

'PERMANENT_SESSION_LIFETIME':           timedelta(days=31)

"""

@app.route('/index',endpoint='xx')

def index():

    # session本质上操作的是字典,假设session保存在数据库

    # session['xxx'] = 123

    # session['xx1'] = 123

    # session['xx2'] = 123

    # session['xx3'] = 123

    # del session['xx2']

    session['xx3'] = 123

    return "xxx"

if __name__ == '__main__':

    # app.__call__

    app.run()

八闪现

闪现是基于session实现的，当然用session也可以实现闪现的方法，闪现和session的区别就是闪现用了一次后值就没有了

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

app = Flask(__name__)

app.secret_key ='sdfsdfsdf'

@app.route('/users')

def users():

    # msg = request.args.get('msg','')

    # msg = session.get('msg')

    # if msg:

    #     del session['msg']

    v = get_flashed_messages()

    print(v)

    msg = ''

    return render_template('users.html',msg=msg)

@app.route('/useradd')

def user_add():

    # 在数据库中添加一条数据

    # 假设添加成功，在跳转到列表页面时，显示添加成功

    # return redirect('/users?msg=添加成功')

    # session['msg'] = '添加成功'

    flash('添加成功')

    return redirect('/users')

if __name__ == '__main__':

    app.run()

闪现示例

九扩展(类似与django的中间件)

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

app = Flask(__name__)

app.secret_key ='sdfsdfsdf'

@app.before_request

def process_request1():

    print('process_request1')

@app.after_request

def process_response1(response):

    print('process_response1')

    return response

@app.before_request

def process_request2():

    print('process_request2')

@app.after_request

def process_response2(response):

    print('process_response2')

    return response

@app.route('/index')

def index():

    print('index')

    return 'Index'

@app.route('/order')

def order():

    print('order')

    return 'order'

@app.route('/test')

def test():

    print('test')

    return 'test'

if __name__ == '__main__':

    app.run()

import pymysql

from  urllib.parse import urlencode

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

from utils.pager import Pagination

app = Flask(__name__)

app.secret_key = 'ctz123'

app.config

class MysqlCon(object):

    @classmethod

    def getCon(cls):

        con = pymysql.connect(host="localhost", user="root", password="root", database="pro1", charset="utf8")

        return con

VALID_URL = ['/login', ]

@app.route('/')

def hello_world():

    return 'Hello World!'

@app.before_request

def peocess_request():

    user = session.get('user')

    if request.path in VALID_URL:

        return None

    if not user:

        return redirect('/login')

@app.route('/login', methods=['POST', 'GET'], strict_slashes=False)

def login():

    if request.method == 'GET':

        return render_template('login.html')

    else:

        username = request.form.get('username')

        pwd = request.form.get('pwd')

        con = MysqlCon.getCon()

        cursor = con.cursor(cursor=pymysql.cursors.DictCursor)

        sql_user = 'select * from userinfo where username=%s and pwd=%s'

        cursor.execute(sql_user, [username, pwd])

        cursor.close()

        con.close()

        user = cursor.fetchone()

        if user:

            session['user'] = {'username': username, 'pwd': pwd}

            return redirect('/userlist')

        else:

            return render_template('login.html', msg='用户名或密码错误')

@app.route('/userlist', methods=['POST', 'GET'], strict_slashes=False)

def userlist():

    con = MysqlCon.getCon()

    cursor = con.cursor(cursor=pymysql.cursors.DictCursor)

    sql_list = 'select * from userinfo'

    cursor.execute(sql_list)

    userlist = cursor.fetchall()

    current_page = request.args.get('page', 1)

    total_count = len(userlist)

    cursor.close()

    con.close()

    base_url = request.path

    parmas = request.args.to_dict()

    pageObj = Pagination(current_page, total_count, base_url, parmas)

    per_page_list = userlist[pageObj.start:pageObj.end]

    return render_template('list.html', userlist=per_page_list, pageObj=pageObj)

@app.route('/adduser', methods=['GET', 'POST'], strict_slashes=False)

def addUser():

    if request.method == 'GET':

        return render_template('addUser.html')

    else:

        username = request.form.get('username')

        pwd = request.form.get('pwd')

        age = request.form.get('age')

        email = request.form.get('email')

        print(username, pwd, age, email)

        con = MysqlCon.getCon()

        cursor = con.cursor(cursor=pymysql.cursors.DictCursor)

        sql = 'insert into userinfo(username,pwd,age,email)values(%s,%s,%s,%s)'

        cursor.execute(sql, [username, pwd, age, email])

        con.commit()

        cursor.close()

        con.close()

        return redirect('/userlist')

@app.route('/edituser/<int:sid>', methods=['GET', 'POST'])

def editUser(sid):

    if request.method == 'GET':

        con = MysqlCon.getCon()

        cursor = con.cursor(cursor=pymysql.cursors.DictCursor)

        sql = 'select * from userinfo where id=%s'

        cursor.execute(sql, [sid, ])

        user = cursor.fetchone()

        cursor.close()

        con.close()

        return render_template('editUser.html', user=user)

    else:

        parmars = urlencode(request.args.to_dict())

        con = MysqlCon.getCon()

        cursor = con.cursor(cursor=pymysql.cursors.DictCursor)

        username = request.form.get('username')

        pwd = request.form.get('pwd')

        age = request.form.get('age')

        email = request.form.get('email')

        sql = 'update userinfo set username=%s,pwd=%s,age=%s,email=%s where id=%s'

        cursor.execute(sql, [username, pwd, age, email, sid])

        con.commit()

        cursor.close()

        con.close()

        return redirect('%s?%s' % ('/userlist', parmars))

@app.route('/deluser/<int:sid>', methods=['POST', 'GET'])

def delUser(sid):

    con = MysqlCon.getCon()

    cursor = con.cursor(cursor=pymysql.cursors.DictCursor)

    sql = 'delete from userinfo where id=%s'

    cursor.execute(sql, [sid, ])

    con.commit()

    cursor.close()

    con.close()

    parmars = urlencode(request.args.to_dict())

    return redirect('%s?%s' % ('/userlist', parmars))

if __name__ == '__main__':

    app.run(debug=True)

示例

十、蓝图

目录结构

from flask import Blueprint,render_template

account = Blueprint('account',__name__,)

@account.route('/login')

def login():

    # return 'Login'

    return render_template('login.html')

acount.py

from flask import Blueprint

order = Blueprint('order',__name__)

@order.route('/order')

def login():

    return 'Order'

order.py

from flask import Flask

from .views import account

from .views import order

app = Flask(__name__)

print(app.root_path)

app.register_blueprint(account.account)

app.register_blueprint(order.order)

__init__.py

import fcrm

if __name__ == '__main__':

    fcrm.app.run(port=8001)

manage.py

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

    <h1>登录页面</h1>

</body>

</html>

详细 http://docs.jinkan.org/docs/flask/index.html