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