flask的简单使用

一.Flask中的CBV

from flask import Flask, render_template

from flask import views

app = Flask(__name__, template_folder='temp')  # type:Flask

app.config['DEBUG'] = True

 

 

class LoginView(views.MethodView):   

 

    def get(self):

        return render_template('login.html')

 

    def post(self):

        return '登录成功'

 

 

app.add_url_rule('/login', endpoint=None, view_func=LoginView.as_view('login'))

# 路由地址   指定endpoint为none   as_view中的login为endpoint  

 

if __name__ == '__main__':

    app.run()

 

二. Flask 中的闪现(flash)

from flask import flash

flash('666', 'hu')

get_flashed_messages('hu')   # 结果[('hu','666')]

get_flashed_messages(category_filter='hu')

flash('666')

get_flashed_messages()        # 结果['666']

三. Flask-Session

 

    from flask_session import Session

    from flask import session

    

    app.config["SESSION_TYPE"] = "redis"

    app.config["SESSION_REDIS"] = Redis("127.0.0.1",6379,db=7)

    Session(app)

    

    session["user"] = "123"

    session.get("user")

flask中的session存放在浏览器中的cookie中

四.Flask中的WTForms

 

class ResForm(Form):

    username = simple.StringField(

        label='用户名',

        validators=[

            validators.DataRequired(message='用户名不能为空'),

            validators.Length(min=4, message='用户名不能低于五位数')

        ]

    )

    password =  simple.PasswordField(

        label='密码',

        validators=[

            validators.DataRequired(message='密码不能为空'),

            validators.Length(min=4,message='密码不能低于五位数')

        ]

    )

    re_password =  simple.PasswordField(

        label='确认密码',

        validators=[

            validators.DataRequired(message='密码不能为空'),

            validators.Length(min=4,message='密码不能低于五位数'),

            validators.EqualTo('password', message='密码不一致')

        ]

    )

    email = simple.StringField( label='邮箱',

        validators=[

            validators.Email(message='格式不正确'),

        ])

    sex = core.SelectField(

        label='性别',

        coerce=int,

        choices=((1, '男'),

                 (2, '女')

                 ),

        default=1

    )

    hobby = core.SelectMultipleField(

        label='爱好',

        coerce=int,

        choices=((1, '小萝莉'),

                 (2, '御姐'),

                 (3, '淑女'),

                 (4, '熟女'),

                 ),

        default=(1, 2 )

    )

 

五.DBUtils 数据库连接池

 

from DBUtils.PooledDB import PooledDB

import pymysql

 

class MySQLhelper(object):

    def __init__(self, host, port, dbuser, password, database):

        self.pool = PooledDB(

            creator=pymysql,  # 使用链接数据库的模块

            maxconnections=6,  # 连接池允许的最大连接数，0和None表示不限制连接数

            mincached=2,  # 初始化时，链接池中至少创建的空闲的链接，0表示不创建

            maxcached=5,  # 链接池中最多闲置的链接，0和None不限制

            maxshared=3,

            # 链接池中最多共享的链接数量，0和None表示全部共享。PS: 无用，因为pymysql和MySQLdb等模块的 threadsafety都为1，所有值无论设置为多少，_maxcached永远为0，所以永远是所有链接都共享。

            blocking=True,  # 连接池中如果没有可用连接后，是否阻塞等待。True，等待；False，不等待然后报错

            maxusage=None,  # 一个链接最多被重复使用的次数，None表示无限制

            setsession=[],  # 开始会话前执行的命令列表。如：["set datestyle to ...", "set time zone ..."]

            ping=0,

            # ping MySQL服务端，检查是否服务可用。# 如：0 = None = never, 1 = default = whenever it is requested, 2 = when a cursor is created, 4 = when a query is executed, 7 = always

            host=host,

            port=int(port),

            user=dbuser,

            password=password,

            database=database,

            charset='utf8'

        )

 

    def create_conn_cursor(self):

        conn = self.pool.connection()

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

        return conn,cursor

 

    def fetch_all(self, sql, args):

        conn,cursor = self.create_conn_cursor()

        cursor.execute(sql,args)

        result = cursor.fetchall()

        cursor.close()

        conn.close()

        return result

 

    def insert_one(self,sql,args):

        conn,cursor = self.create_conn_cursor()

        res = cursor.execute(sql,args)

conn.commit()

        conn.close()

        return res

 

    def update(self,sql,args):

        conn,cursor = self.create_conn_cursor()

        res = cursor.execute(sql,args)

conn.commit()

        print(res)

        conn.close()

        return res

 

 

sqlhelper = MySQLhelper("127.0.0.1", 3306, "root", "", "db7")

 

# res = sqlhelper.fetch_all("select * from userinfo where id=%s",(5,))

# print(res)

 

# res = sqlhelper.insert_one("insert into userinfo VALUES (%s,%s,%s)",(7,"jinwangba","66666"))

# print(res)

 

# sqlhelper.update("update user SET name=%s WHERE  id=%s",("yinwangba",1))

六.Flask请求上下文流程

 

https://www.processon.com/view/5ae87bcde4b019d3a91b8047  request请求上下文流程