Flask framework in-depth two

FlaskThe framework goes deep into two

一、flask-session

# 原生的sessionThe data is encrypted and placedcookie中
# 以后可以把session放在数据库中,redis,文件中....
# pip install flask-session

# 方式一
from flask import Flask,session
from flask_session import RedisSessionInterface
import redis
app = Flask(__name__)
app.config['DEBUG'] = True
conn = redis.Redis()
app.session_interface = RedisSessionInterface(conn,key_prefix='zz')
@app.route('/')
def index():
    session['name'] = 'zhangzhang'
    return 'hello flask!'

if __name__ == '__main__':
    app.run()
    
    
# 方式二：（通用方案：flaskIntegrate third-party common solutions）
from flask_session import Session
# 配置文件
app.config['SESSION_TYPE'] = 'redis'
app.config['SESSION_KEY_PREFIX'] = 'lqz'
app.config['SESSION_REDIS'] = redis.Redis()
Session(app)  # 源码在这---》Inside is done app.session_interface=RedisSessionInterface(app.config['SESSION_REDIS'])
@app.route('/')
def index():
    session['name'] = 'lqz'
    return 'hello'


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

二、数据库连接池

# Why have a database connection pool
	-With the increasing amount of concurrency,mysqlThe number of connections will also increase---》After we create the connection pool,Used every time a connection is obtained from the pool,Can avoid excessive concurrency,The danger of database collapse
    
# pip install dbutils

# 创建池对象
from flask import Flask, session
from dbutils.pooled_db import PooledDB
import pymysql
app = Flask(__name__)
app.config['DEBUG'] = True
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='127.0.0.1',  # 数据库地址
    port=3306,         # 数据库端口
    user='root',       # 数据库用户名
    password='786017877',    # 数据库密码
    database='knowgood',# 数据库名称
    charset='utf8'     # 数据库编码
)


@app.route('/')
def index():
    # Take the link from the pool
    conn = POOL.connection()
    cursor = conn.cursor()
    cursor.execute('select * from applet_user')
    print(cursor.fetchall())
    return 'hello flask!'


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

# 了解
	-django和flaskBoth are synchronous frameworks
    	-来一个请求,Start the thread to execute the view function
    -异步框架：sanic,fastapi,只要被async装饰的函数,is the coroutine function
    	@app.route("/")
        async def test(request):
            await cousor.excute()
            return json({
    "hello": "world"})
        
        
        
# 协程：单线程下实现并发 


# 一旦用了异步,All frameworks must use async
	-pymysql,redis是同步框架
    -Cannot be used in asyncweb框架中
    -Requires the use of specialized async modules
    -aiomysql,aioredis,python到目前为止,There isn't a better asyncorm框架
    
    -django 3.0以后支持异步
    	-但是django的orm不支持异步
        
   -python的orm框架
	-django的orm：同步
    -sqlalchemy：同步
    -peewee：同步和异步
    
    
# aioredis和aiomysql的使用

# Why once use an asynchronous framework,All use asynchronous

三、wtfroms（了解）

# 等同于django的forms,表单验证,模板渲染,Suitable for projects with mixed front-end and back-end

1、登录案例

from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgets

app = Flask(__name__)

app.debug = True

# 写了个form类
class LoginForm(Form):
    # 字段（内部包含正则表达式）
    name = simple.StringField(
        label='用户名',
        validators=[
            validators.DataRequired(message='用户名不能为空.'),
            validators.Length(min=6, max=18, message='用户名长度必须大于%(min)d且小于%(max)d')
        ],
        widget=widgets.TextInput(), # 页面上显示的插件
        render_kw={
    'class': 'form-control'}

    )
    # 字段（内部包含正则表达式）
    pwd = simple.PasswordField(
        label='密码',
        validators=[
            validators.DataRequired(message='密码不能为空.'),
            validators.Length(min=8, message='用户名长度必须大于%(min)d'),
            validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[[email protected]$!%*?&])[A-Za-z\[email protected]$!%*?&]{8,}",
                              message='密码至少8个字符,至少1个大写字母,1个小写字母,1个数字和1个特殊字符')

        ],
        widget=widgets.PasswordInput(),
        render_kw={
    'class': 'form-control'}
    )



@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'GET':
        form = LoginForm()
        return render_template('login.html', form=form)
    else:
        form = LoginForm(formdata=request.form)
        if form.validate():
            print('用户提交数据通过格式验证,提交的值为：', form.data)
        else:
            print(form.errors)
        return render_template('login.html', form=form)

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

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>登录</h1>
<form method="post">
    <p>{
   {form.name.label}} {
   {form.name}} {
   {form.name.errors[0] }}</p>

    <p>{
   {form.pwd.label}} {
   {form.pwd}} {
   {form.pwd.errors[0] }}</p>
    <input type="submit" value="提交">
</form>
</body>
</html>

2、注册案例

from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import core
from wtforms.fields import html5
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgets

app = Flask(__name__, template_folder='templates')
app.debug = True



class RegisterForm(Form):
    name = simple.StringField(
        label='用户名',
        validators=[
            validators.DataRequired()
        ],
        widget=widgets.TextInput(),
        render_kw={
    'class': 'form-control'},
        default='egon'
    )

    pwd = simple.PasswordField(
        label='密码',
        validators=[
            validators.DataRequired(message='密码不能为空.')
        ],
        widget=widgets.PasswordInput(),
        render_kw={
    'class': 'form-control'}
    )

    pwd_confirm = simple.PasswordField(
        label='重复密码',
        validators=[
            validators.DataRequired(message='重复密码不能为空.'),
            validators.EqualTo('pwd', message="两次密码输入不一致")
        ],
        widget=widgets.PasswordInput(),
        render_kw={
    'class': 'form-control'}
    )

    email = html5.EmailField(
        label='邮箱',
        validators=[
            validators.DataRequired(message='邮箱不能为空.'),
            validators.Email(message='邮箱格式错误')
        ],
        widget=widgets.TextInput(input_type='email'),
        render_kw={
    'class': 'form-control'}
    )

    gender = core.RadioField(
        label='性别',
        choices=(
            (1, '男'),
            (2, '女'),
        ),
        coerce=int # “1” “2”
     )
    city = core.SelectField(
        label='城市',
        choices=(
            ('bj', '北京'),
            ('sh', '上海'),
        )

    )

    hobby = core.SelectMultipleField(
        label='爱好',
        choices=(
            (1, '篮球'),
            (2, '足球'),
        ),
        coerce=int
    )

    favor = core.SelectMultipleField(
        label='喜好',
        choices=(
            (1, '篮球'),
            (2, '足球'),
        ),
        widget=widgets.ListWidget(prefix_label=False),
        option_widget=widgets.CheckboxInput(),
        coerce=int,
        default=[1, 2]
    )

    def __init__(self, *args, **kwargs):
        super(RegisterForm, self).__init__(*args, **kwargs)
        self.favor.choices = ((1, '篮球'), (2, '足球'), (3, '羽毛球'))

    def validate_pwd_confirm(self, field):
        """ 自定义pwd_confirm字段规则,例：与pwd字段是否一致 :param field: :return: """
        # 最开始初始化时,self.data中已经有所有的值

        if field.data != self.data['pwd']:
            # raise validators.ValidationError("密码不一致") # 继续后续验证
            raise validators.StopValidation("密码不一致")  # 不再继续后续验证


@app.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'GET':
        form = RegisterForm(data={
    'gender': 2,'hobby':[1,]}) # initial
        return render_template('register.html', form=form)
    else:
        form = RegisterForm(formdata=request.form)
        if form.validate():
            print('用户提交数据通过格式验证,提交的值为：', form.data)
        else:
            print(form.errors)
        return render_template('register.html', form=form)



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

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>用户注册</h1>
<form method="post" novalidate style="padding:0 50px">
    {
    % for field in form %}
    <p>{
    {
    field.label}}: {
    {
    field}} {
    {
    field.errors[0] }}</p>
    {
    % endfor %}
    <input type="submit" value="提交">
</form>
</body>
</html>

四、信号（重要）

1、Flask信号

Flask框架中的信号基于blinker,其主要就是让开发者可是在flask请求过程中定制一些用户行为(Such as operation records are written to the log,或者写入数据库)

# Multi-threaded concurrency safety issues：Multiple threads operate on the same data at the same time,出现错乱
# 使用同步锁--》Get it before modifying the data---》开始修改---》释放锁--》someone else will take it

# 线程锁----》分布式锁
# 悲观锁和乐观锁
# 同步锁（互斥锁）,递归锁（可重入锁）,Event事件,Semaphore（信号量）多把锁


# 安装：pip3 install blinker
内置信号
request_started = _signals.signal('request-started')                # 请求到来前执行
request_finished = _signals.signal('request-finished')              # 请求结束后执行
 
before_render_template = _signals.signal('before-render-template')  # 模板渲染前执行
template_rendered = _signals.signal('template-rendered')            # 模板渲染后执行
 
got_request_exception = _signals.signal('got-request-exception')    # 请求执行出现异常时执行
 
request_tearing_down = _signals.signal('request-tearing-down')      # 请求执行完毕后自动执行（无论成功与否）
appcontext_tearing_down = _signals.signal('appcontext-tearing-down')# 应用上下文执行完毕后自动执行（无论成功与否）
 
appcontext_pushed = _signals.signal('appcontext-pushed')            # 应用上下文push时执行
appcontext_popped = _signals.signal('appcontext-popped')            # 应用上下文pop时执行
message_flashed = _signals.signal('message-flashed')                # 调用flask在其中添加数据时,自动触发

# 自定义信号（我们自定义的）

# 内置信号使用
# The built-in signal performs the usage steps：
# The signal executes after the template is rendered
# 功能：home页面被渲染,记录一条日志
# 第一步：写一个函数
def template_test(*args,**kwargs):
    print(args)
    print(kwargs)
    print('The template is rendered')
# 第二步：Bind to the built-in signal：template_rendered
template_rendered.connect(template_test)
# 第三不：Trigger signal execution（We don't need to do it）

### 自定义信号的使用
###### Custom signal steps
# 第0步：自定义一个信号
xxxxx = _signals.signal('xxxxx')
# 第一步：写一个函数
def xxx_test(*args, **kwargs):
    print(args)
    print(kwargs)
    print('xxxThe signal is triggered')


# 第二步：Bind the custom signal signal：xxxxx
xxxxx.connect(xxx_test)


# 第三步：Trigger signal execution（手动触发,trigger at a certain location,For example, in the view function）


@app.route('/')
def index():
    xxxxx.send()  # 触发信号
    return 'hello'

2、Django信号

# 内置信号
Model signals
    pre_init                    # django的modal执行其构造方法前,自动触发
    post_init                   # django的modal执行其构造方法后,自动触发
    pre_save                    # django的modal对象保存前,自动触发
    post_save                   # django的modal对象保存后,自动触发
    pre_delete                  # django的modal对象删除前,自动触发
    post_delete                 # django的modal对象删除后,自动触发
    m2m_changed                 # django的modal中使用m2m字段操作第三张表（add,remove,clear）前后,自动触发
    class_prepared              # 程序启动时,检测已注册的app中modal类,对于每一个类,自动触发
Management signals
    pre_migrate                 # 执行migrate命令前,自动触发
    post_migrate                # 执行migrate命令后,自动触发
Request/response signals
    request_started             # 请求到来前,自动触发
    request_finished            # 请求结束后,自动触发
    got_request_exception       # 请求异常后,自动触发
Test signals
    setting_changed             # 使用test测试修改配置文件时,自动触发
    template_rendered           # 使用test测试渲染模板时,自动触发
Database Wrappers
    connection_created          # 创建数据库连接时,自动触发

    
#放到__init__里
from django.db.models.signals import pre_save
import logging
def callBack(sender, **kwargs):
    print(sender)
    print(kwargs)
    # 创建对象写日志
    logging.basicConfig(level=logging.DEBUG)
    # logging.error('%s创建了一个%s对象'%(sender._meta.db_table,kwargs.get('instance').title))
    logging.debug('%s创建了一个%s对象'%(sender._meta.model_name,kwargs.get('instance').title))

pre_save.connect(callBack)

五、flask-script

1、启动命令

# Implement a command like this：python manage.py runserver
# 自定义命令：

# django 自定义命令
	python manage.py initdb xx.xsl article  #Just execute this command,to the databasearticle表中写入xx.xsl的数据

 # pip3 install flask-script

####基本使用
from flask import Flask


app = Flask(__name__)
# 第一步导入
from flask_script import Manager
# The second step is packaging
manager = Manager(app)


@app.route('/')
def index():
    return 'hello'


if __name__ == '__main__':
    # app.run()
    # 第三步使用
    manager.run()

2、自定义命令

######### 自定义命令
@manager.command
def custom(arg):
    """ 自定义命令 python manage.py custom 123 :param arg: :return: """
    print(arg)


@manager.option('-n', '--name', dest='name')
@manager.option('-u', '--url', dest='url')
def cmd(name, url):
    """ 自定义命令（-n也可以写成--name） 执行： python manage.py cmd -n lqz -u http://www.oldboyedu.com 执行： python manage.py cmd --name lqz --url http://www.oldboyedu.com :param name: :param url: :return: """
    print(name, url)