"前言： Python 主流 WEB 框架对比 Django:1 个重武器，包含了 web 开发中常用的功能、组件的框架；（ORM、Session、Form、Admin、分页、中间件、信号、缓存、ContenType....）； Tornado:2 大特性就是异步非阻塞、原生支持 WebSocket ...."

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AI开发者社区 • 0 回帖 • 17 浏览 • 4 个月前

PythonWEB框架之Flask

前言：

Python 主流 WEB 框架对比

Django:1 个重武器，包含了 web 开发中常用的功能、组件的框架；（ORM、Session、Form、Admin、分页、中间件、信号、缓存、ContenType....）；

Tornado:2 大特性就是异步非阻塞、原生支持 WebSocket 协议；

Flask：封装功能不及 Django 完善，性能不及 Tornado，但是 Flask 可扩展性强，因为 flask 的第三方开源组件丰富；

Bottle：比较简单；

结论

都不是我写的！！！不论优劣，不同的工具而已；

小型 web 应用设计的功能点不多使用 Flask；

大型 web 应用设计的功能点比较多使用的组件也会比较多，使用 Django（自带功能多不用去找插件）；

如果追求性能可以考虑 Tornado；

WSGI 介绍

Django 使用 wsgiref 模块 Flask 使用 Werkzeug 模块实现了 WSGI 协议。

HTTP 协议是建立在 TCP 协议之上的，实现 UWSGI 协议本质是实现 Socket 服务端，也就是 TCP 层实现 HTTP 请求的接收、对请求内容进行预处理如分割 HTPP 请求内容的 Header 和 body，然后再触发后面的 Django/Flask 框架。

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

pip3 install flask           #安装 flask

Flask 框架是基于 werkzeug 模块实现的。

from werkzeug.wrappers import Request,Response
from werkzeug.serving import run_simple
@Request.application
def hello(request):
    return Response("Hello World")
if name == 'main':
#请求一旦到来，执行第 3 个参数，hello(上下文)
run_simple('localhost', 4000, hello)

Flask 简单使用

from flask import Flask
app=Flask(name) #创建 1 个 Flask 实例

@app.route('/')      #路由系统生成 视图对应 url,1. decorator=app.route()2. decorator(first_flask)
def first_flask():    #视图函数
return 'Hello World'  #response
if name == 'main':
app.run()              #启动 socket

View Code

一、配置文件

app=Flask(__name__,template_folder='templates',static_url_path='/static/',static_path='/zhanggen')

模板路径： template_folder='templates'

静态文件路径：static_url_path='/static/'

静态文件引入别名：static_path='/zhanggen'

设置为调试环境：app.debug=True （代码修改自动更新）

设置 json 编码格式如果为 False 就不使用 ascii 编码：app.config['JSON_AS_ASCII']=False

设置响应头信息 Content-Type app.config['JSONIFY_MIMETYPE'] ="application/json;charset=utf-8" （注意 ;charset=utf-8）

二、路由系统

1. 动态路由（url 传参）

@app.route('/user/<name>')

from flask import Flask
app=Flask(name)
@app.route('/<name>')  #设置 url 传参数 http://127.0.0.1:5000/zhanggen
def first_flask(name):  #视图必须有对应接收参数
print(name)
return 'Hello World'  #response
if name == 'main':
app.run()

接收字符串类型参数

@app.route('/post/<int:age>')

#接收整型数字参数
app=Flask(__name__)
@app.route('/<int:age>/')  #设置 url 传参数 http://127.0.0.1:5000/18/
def first_flask(age):  #视图必须有对应接收参数
    print(age)
    return 'Hello World'  #response
if name == 'main':
app.run()

接收整型数字参数

@app.route('/post/<float:salary>')

#接收浮点型型数字参数
app=Flask(__name__)
@app.route('/<float:salary>/')  #设置 url 传参数 http://127.0.0.1:5000/2345555.8889/
def first_flask(salary):  #视图必须有对应接收参数
    print(salary)
    return 'Hello World'  #response
if name == 'main':
app.run()

接收浮点型数字参数

@app.route('/post/<path:path>')

# 接收 URL 链接类型参数
app=Flask(__name__)
@app.route('/<path:url>/')  #设置 url 传参数：http://127.0.0.1:5000/http://www.baiu.com/
def first_flask(url):  #视图必须有对应接收参数
    print(url)
    return 'Hello World'  #response
if name == 'main':
app.run()

接收 URL 链接类型参数

2、指定允许的请求方法

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

# 指定允许的请求方法
app=Flask(__name__)
@app.route('/<path:url>/',methods=['get']) #只允许 get 请求
def first_flask(url):
    print(url)
    return 'Hello World'  #response
if name == 'main':
app.run()

指定允许的请求方法

3、通过别名反向生成 url

#反向生成 url
from flask import Flask,url_for
app=Flask(__name__)
@app.route('/<path:url>',endpoint='name1')
def first_flask(url):
    print(url_for('name1',url=url)) #如果设置了 url 参数，url_for（别名, 加参数）
    return 'Hello World'
if name == 'main':
app.run()

url_for() 反向生成 url

4、通过 app.add_url_rule() 调用路由

#方式 2 通过 app.add_url_rule() 方法的方式调用路由
app=Flask(__name__)
def first_flask():
return 'Hello World'
app.add_url_rule(rule='/index/',endpoint='name1',view_func=first_flask,methods=['GET'])
#app.add_url_rule(rule= 访问的 url,endpoint= 路由别名,view_func= 视图名称,methods=[ 允许访问的方法])
if name == 'main':
app.run()

app.add_url_rule() 方法调用路由

5、扩展路由功能：正则匹配 url

如果需要一些复杂的匹配规则可以自定义正则匹配 url

    from flask import Flask, views, url_for
            from werkzeug.routing import BaseConverter
        app </span>= Flask(import_name=<span style="color: rgba(128, 0, 128, 1)">__name__</span><span style="color: rgba(0, 0, 0, 1)">)


        </span><span style="color: rgba(0, 0, 255, 1)">class</span><span style="color: rgba(0, 0, 0, 1)"> RegexConverter(BaseConverter):
            </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(128, 0, 0, 1)">
            自定义URL匹配正则表达式
            </span><span style="color: rgba(128, 0, 0, 1)">"""</span>
            <span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__init__</span><span style="color: rgba(0, 0, 0, 1)">(self, map, regex):
                super(RegexConverter, self).</span><span style="color: rgba(128, 0, 128, 1)">__init__</span><span style="color: rgba(0, 0, 0, 1)">(map)
                self.regex </span>=<span style="color: rgba(0, 0, 0, 1)"> regex

            </span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> to_python(self, value):
                </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(128, 0, 0, 1)">
                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: 
                </span><span style="color: rgba(128, 0, 0, 1)">"""</span>
                <span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> int(value)

            </span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> to_url(self, value):
                </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(128, 0, 0, 1)">
                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: 
                </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(0, 0, 0, 1)">
                val </span>=<span style="color: rgba(0, 0, 0, 1)"> super(RegexConverter, self).to_url(value)
                </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> val

        </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 添加到flask中</span>
        app.url_map.converters[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">regex</span><span style="color: rgba(128, 0, 0, 1)">'</span>] =<span style="color: rgba(0, 0, 0, 1)"> RegexConverter


        @app.route(</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">/index/&lt;regex("\d+"):nid&gt;</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
        </span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> index(nid):
            </span><span style="color: rgba(0, 0, 255, 1)">print</span>(url_for(<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">index</span><span style="color: rgba(128, 0, 0, 1)">'</span>, nid=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">888</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">))
            </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Index</span><span style="color: rgba(128, 0, 0, 1)">'</span>


        <span style="color: rgba(0, 0, 255, 1)">if</span> <span style="color: rgba(128, 0, 128, 1)">__name__</span> == <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">__main__</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
            app.run()</span></pre>

自定义正则表达式匹配路由

四、视图

1、给 Flask 视图函数加装饰器

注意如果要给视图函数加装饰器增加新功能，一点要加在路由装饰器下面，才会被路由装饰器装饰，才能生生成 url 关系；

#给 Flask 视图加装饰器
#1、定义 1 个装饰器
def auth(func):
print('我在上面')
def inner(*args,kwargs):
return func(*args,kwargs)
return inner
app=Flask(name)
@app.route('/',methods=['GET'])
@auth #注意如果要给视图函数加装饰器，一点要加在路由装饰器下面，才会被路由装饰器装饰
def first_flask():
print('ffff')
return 'Hello World'
if name == 'main':
app.run()

View Code

2、request 和 response

a. 请求相关信息

request.method：获取请求方法

request.json

request.json.get("json_key")：获取 json 数据 ** 较常用

request.argsget('name') ：获取 get 请求参数

request.form.get('name') ：获取 POST 请求参数

request.form.getlist('name_list')：获取 POST 请求参数列表（多个）

request.values.get('age') ：获取 GET 和 POST 请求携带的所有参数（GET/POST 通用）

request.cookies.get('name')：获取 cookies 信息

request.headers.get('Host')：获取请求头相关信息

request.path：获取用户访问的 url 地址，例如（/，/login/，/ index/）；

request.full_path：获取用户访问的完整 url 地址 + 参数例如 (/login/?age=18)

request.script_root：抱歉，暂未理解其含义；

request.url：获取访问 url 地址，例如 http://127.0.0.1:5000/?age=18；

request.base_url：获取访问 url 地址，例如 http://127.0.0.1:5000/；

request.url_root

request.host_url

request.host：获取主机地址

request.files：获取用户上传的文件

obj = request.files['the_file_name']

obj.save('/var/www/uploads/' + secure_filename(f.filename)) 直接保存

b、响应相关信息

return "字符串" ：响应字符串

return render_template('html 模板路径',**{})：响应模板

return redirect('/index.html')：跳转页面

响应 json 数据

方式 1： return jsonify(user_list)

app.config['JSON_AS_ASCII']=False  #指定 json 编码格式 如果为 False 就不使用 ascii 编码，
app.config['JSONIFY_MIMETYPE'] ="application/json;charset=utf-8" #指定浏览器渲染的文件类型，和解码格式；

配置

方式 2：

return Response(data,mimetype="application/json;charset=utf-8",)

如果需要设置响应头就需要借助 make_response() 方法

from flask import Flask,request,make_response

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 respons

3 、Flask 之 CBV 视图

#CBV 视图
from flask import Flask,url_for,views
#-----------------------------------------------------
app=Flask(__name__)               #装饰器
def auth(func):
print('我在上面')
def inner(*args,kwargs):
return func(*args,kwargs)
return inner
#--------------------------------------------------------
class IndexView(views.MethodView):  #CBV 视图
methods=['GET']                #允许的 http 请求方法（改 CBV 只允许 GET 方法）
decorators = [auth,]            #每次请求过来都加 auth 装饰器
<span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> get(self):
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Index.GET</span><span style="color: rgba(128, 0, 0, 1)">'</span>
<span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> post(self):
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Index.POST</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">

app.add_url_rule('/index/',view_func=IndexView.as_view(name='name1')) #(name='name1' 反向生成 url 别名
if name == 'main':
app.run()

CBV 视图

五、模板语言

Flask 使用的是 Jinja2 模板，所以其语法和 Django 无差别（Django 的模板语言参考 Jinja2）

1. 引用静态文件

方式 1：别名引入

<link rel="stylesheet" href="/zhanggen/commons.css">

方式 2：url_for() 方法引入

<link rel="stylesheet" href="{{url_for('static',filename='commons.css')  }}">

2. 模板语言引用上下文对象

变量

<h1>{{user_list}}</h1> <!-- 变量 -->

View Code

循环、索引取值

<ul>
{% for user in user_list %}   <!-- 循环 -->
    <li>{{user}}</li>
{% endfor %}
{{user_list.0}}             <!-- 索引取值 -->
</ul>

View Code

Flask 的 Jinjia2 可以通过 Context 把视图中的函数传递把模板语言中执行，这就是 Django 中的 simple_tag 和 simple_fifter；

simple_tag（只能传 2 个参数, 支持 for、if）

@app.template_global()   #simple_tag
def foo(arg):
    return '<input type="text">'

视图

<h1>{{foo(1)|safe}}</h1>                   <!--Flask 的模板语言支持 simple_tag-->

模板语言

simple_fifter（对参数个数无限制，不支持 for、if）

@app.template_filter()  #simple_fifter
def foo1(arg1,arg2,arg3):
    return arg1+arg2+arg3

视图

<h1> {{'alex'|foo1('s','b',) }}  </h1>     <!-- simple_fifter -->

模板语言

3.wtform（flask 表单验证插件）

3.0. 简介

wtforms WTForms 是一个支持多个 web 框架的 form 组件，主要对用户请求数据进行表单验证。

3.1. 安装

pip install wtforms  #安装 wtfroms 插件

3.2. 简单使用

wtforms 和 Django 自带的 form 验证插件功能相同，使用起来大同小异；

用户登录页面验证

#!/usr/bin/env python
# -*- coding:utf-8 -*-
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') #知道模板文件
app.debug=True
#登录验证实例
class LoginForm(Form):
</span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">不同的字段 内部包含正则表达式 html5.EmailField | html5.DateTimeField...</span>
name=<span style="color: rgba(0, 0, 0, 1)">simple.StringField(
    label</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">用户名</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    validators</span>=[                                <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">验证规则和错误提示信息</span>
        validators.DataRequired(message=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">用户名不能为空.</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        validators.Length(min</span>=6, max=18, message=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">用户名长度必须大于%(min)d且小于%(max)d</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
    ],
    widget</span>=widgets.TextInput(),                 <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">前端页面显示的插件.TextArea</span>
    render_kw={<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">class</span><span style="color: rgba(128, 0, 0, 1)">'</span>: <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">form-control</span><span style="color: rgba(128, 0, 0, 1)">'</span>}      <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">设置form标签的class信息</span>


        )
</span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 不同的字段 内部包含正则表达式  html5.EmailField | html5.DateTimeField...</span>
pwd =<span style="color: rgba(0, 0, 0, 1)"> simple.PasswordField(
    label</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">密码</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    validators</span>=<span style="color: rgba(0, 0, 0, 1)">[
        validators.DataRequired(message</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">密码不能为空.</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        validators.Length(min</span>=8, message=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">用户名长度必须大于%(min)d</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">自定义验证规则</span>
        validators.Regexp(regex=<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&amp;])[A-Za-z\d$@$!%*?&amp;]{8,}</span><span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(0, 0, 0, 1)">,
                          message</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">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</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)

    ],
    widget</span>=<span style="color: rgba(0, 0, 0, 1)">widgets.PasswordInput(),
    render_kw</span>={<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">class</span><span style="color: rgba(128, 0, 0, 1)">'</span>: <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">form-control</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">}
)

@app.route('/login/', methods=['GET', 'POST'])
def login():
if request.method == 'GET':
form = LoginForm()     #实例化 form 验证类
return render_template('login.html', form=form)
else:
form = LoginForm(formdata=request.form)
if form.validate(): #判断是否验证成功？
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()

app01.py

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>登录</h1>
<form method="post" novalidate>
    <!--<input type="text" name="name">-->
    <p>{{form.name.label}} {{form.name}} {{form.name.errors[0] }}</p>
<span style="color: rgba(0, 128, 0, 1)">&lt;!--</span><span style="color: rgba(0, 128, 0, 1)">&lt;input type="password" name="pwd"&gt;</span><span style="color: rgba(0, 128, 0, 1)">--&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">p</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>{{form.pwd.label}} {{form.pwd}} {{form.pwd.errors[0] }}<span style="color: rgba(0, 0, 255, 1)">&lt;/</span><span style="color: rgba(128, 0, 0, 1)">p</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>
<span style="color: rgba(0, 0, 255, 1)">&lt;</span><span style="color: rgba(128, 0, 0, 1)">input </span><span style="color: rgba(255, 0, 0, 1)">type</span><span style="color: rgba(0, 0, 255, 1)">="submit"</span><span style="color: rgba(255, 0, 0, 1)"> value</span><span style="color: rgba(0, 0, 255, 1)">="提交"</span><span style="color: rgba(0, 0, 255, 1)">&gt;</span>

</form>
</body>
</html>
login.html

用户注册页面验证

#用户注册
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='张根'                                             #设置 input 标签中默认值
    )
pwd </span>=<span style="color: rgba(0, 0, 0, 1)"> simple.PasswordField(
    label</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">密码</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    validators</span>=<span style="color: rgba(0, 0, 0, 1)">[
        validators.DataRequired(message</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">密码不能为空.</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
    ],
    widget</span>=<span style="color: rgba(0, 0, 0, 1)">widgets.PasswordInput(),
    render_kw</span>={<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">class</span><span style="color: rgba(128, 0, 0, 1)">'</span>: <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">form-control</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">}
)

pwd_confirm </span>= simple.PasswordField(                                <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">第二次输入密码</span>
    label=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">重复密码</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    validators</span>=<span style="color: rgba(0, 0, 0, 1)">[
        validators.DataRequired(message</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">重复密码不能为空.</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        validators.EqualTo(</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">pwd</span><span style="color: rgba(128, 0, 0, 1)">'</span>, message=<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">两次密码输入不一致</span><span style="color: rgba(128, 0, 0, 1)">"</span>)  <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">验证2次输入的密码是否一致？</span>

        ],
widget=widgets.PasswordInput(),
render_kw={'class': 'form-control'}
)
email </span>=<span style="color: rgba(0, 0, 0, 1)"> html5.EmailField(
    label</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">邮箱</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    validators</span>=<span style="color: rgba(0, 0, 0, 1)">[
        validators.DataRequired(message</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">邮箱不能为空.</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        validators.Email(message</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">邮箱格式错误</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
    ],
    widget</span>=widgets.TextInput(input_type=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">email</span><span style="color: rgba(128, 0, 0, 1)">'</span>),    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">生成email input标签</span>
    render_kw={<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">class</span><span style="color: rgba(128, 0, 0, 1)">'</span>: <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">form-control</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">}
)

gender </span>=<span style="color: rgba(0, 0, 0, 1)"> core.RadioField(
    label</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">性别</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    choices</span>=(                                        <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">choice radio选项</span>
        (1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">男</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        (</span>2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">女</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
    ),
    coerce</span>=int                                       <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">讲用户提交过来的 '4' 强制转成 int 4</span>

    )
city = core.SelectField(
label='城市',
choices=(
('bj', '北京'),
('sh', '上海'),
)
)
hobby </span>= core.SelectMultipleField(                      <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">select 下拉框多选框</span>
    label=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">爱好</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    choices</span>=<span style="color: rgba(0, 0, 0, 1)">(
        (</span>1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">篮球</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        (</span>2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">足球</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
    ),
    coerce</span>=<span style="color: rgba(0, 0, 0, 1)">int
)

favor </span>=<span style="color: rgba(0, 0, 0, 1)"> core.SelectMultipleField(
    label</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">喜好</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
    choices</span>=<span style="color: rgba(0, 0, 0, 1)">(
        (</span>1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">篮球</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
        (</span>2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">足球</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">),
    ),
    widget</span>=widgets.ListWidget(prefix_label=False),        <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">生成Checkbox 多选框</span>
    option_widget=<span style="color: rgba(0, 0, 0, 1)">widgets.CheckboxInput(),
    coerce</span>=<span style="color: rgba(0, 0, 0, 1)">int,
    default</span>=[1, 2<span style="color: rgba(0, 0, 0, 1)">]
)

</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__init__</span>(self, *args, **kwargs):                        <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">重写form验证类的__init__方法可以实时同步数据中数据</span>
    super(RegisterForm, self).<span style="color: rgba(128, 0, 128, 1)">__init__</span>(*args, **<span style="color: rgba(0, 0, 0, 1)">kwargs)
    self.favor.choices </span>= ((1, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">篮球</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (2, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">足球</span><span style="color: rgba(128, 0, 0, 1)">'</span>), (3, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">羽毛球</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">))


</span><span style="color: rgba(0, 0, 255, 1)">def</span> validate_pwd_confirm(self, field):                       <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">wtforms验证 钩子函数</span>
    <span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(128, 0, 0, 1)">
    自定义pwd_confirm字段规则，例：与pwd字段是否一致
    :param field:
    :return:
    </span><span style="color: rgba(128, 0, 0, 1)">"""</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 最开始初始化时，self.data中已经有所有的值</span>

    <span style="color: rgba(0, 0, 255, 1)">if</span> field.data != self.data[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">pwd</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">]:
        </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> raise validators.ValidationError("密码不一致") # 继续后续验证</span>
        <span style="color: rgba(0, 0, 255, 1)">raise</span> validators.StopValidation(<span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">密码不一致</span><span style="color: rgba(128, 0, 0, 1)">"</span>)  <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 不再继续后续验证</span>


@app.route('/register/', methods=['GET', 'POST'])
def register():
if request.method == 'GET':
form = RegisterForm(data={'gender': 1})  #默认值
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()

app02.py

<!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 item in form %}
    <p>{{item.label}}: {{item}} {{item.errors[0] }}</p>
    {% endfor %}
    <input type="submit" value="提交">
</form>
</body>
</html>

3.2.wtforms 源码猜想....

A. 自动生成 html 标签

先来分析一下 form 验证类的结构

LoginForm 类中包含了 2 个字段: name 和 pwd，而 name / pwd 字段 = 对象，所以 LoginForm 类包含了 2 个对象；

如果实例化了 obj=LoginForm() 就等于在这 1 个对象中嵌套了 2 个对象；

前端使用 Form 验证插件：

那如果在前端 for 循环 LoginForm 对象，就等于调用 LoginForm 对象的 __iter__ 方法，把每个字段（对象）封装的数据返回

如果前端 {{obj}}= 直接调用了字段对象的 __str__ 方法；

class InputText(object):  #插件
    def __str__(self):
        return '<input type="text" />'
class InputPassword(object):
def str(self):
return '<input type="password" />'
#-----------------------------------------------------------
class StringField(object):  #字段
def init(self,wg):
self.widget=wg
</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__str__</span>(self):      <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">调用插件的__str__</span>
    <span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> str(self.widget)

class DateField(object):
def init(self, wg):
self.widget = wg
</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__str__</span><span style="color: rgba(0, 0, 0, 1)">(self):
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> str(self.widget)

#--------------------------------------------------------------
class LoginForm(object):                #统一 灵活接口 （对象嵌套对象，多层封装）
name=StringField(wg=InputText())     #wg=InputText()对象  StringField(wg=InputText()) 对象
pwd=DateField(wg=InputPassword())
l_obj=LoginForm()
print(l_obj.name)
print(l_obj.pwd)

调用关系

B. 数据校验

后台定义好正则

用户发来数据

对数据进行校验

3.3. 源码流程

生成 HTML 标签并显示

1. 验证类（LogibForm）生成

1.1. 由于 metaclass=FormMeta，所以LoginForm 是由 FormMeta 创建的

'''
class BaseForm():
    pass
class NewBase(BaseForm,metaclass=FormMeta,):
pass
class Form(NewBase):
pass
class LoginForm(Form):
pass
'''
class Form(with_metaclass(FormMeta,BaseForm)):

View Code

1.2. 执行 FormMeta 的 __init__ 方法，在 LoginForm 中添加 2 个静态字段

class FormMeta(type):
    """
    The metaclass for `Form` and any subclasses of `Form`.
`FormMeta`'s responsibility is to create the `_unbound_fields` list, which
is a list of `UnboundField` instances sorted by their order of
instantiation.  The list is created at the first instantiation of the form.
If any fields are added/removed from the form, the list is cleared to be
re-generated on the next instantiation.

Any properties which begin with an underscore or are not `UnboundField`
instances are ignored by the metaclass.
</span><span style="color: rgba(128, 0, 0, 1)">"""</span>
<span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__init__</span><span style="color: rgba(0, 0, 0, 1)">(cls, name, bases, attrs):
    type.</span><span style="color: rgba(128, 0, 128, 1)">__init__</span>(cls, name, bases, attrs) <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">继承type的功能</span>
    cls._unbound_fields = None             <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">在LoginForm中添加1个静态字段</span>
    cls._wtforms_meta = None               <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">在LoginForm中添加1个静态字段</span></pre>

View Code

1.3. 开始解释 LoginForm 中的实例化字段对象name=simple.StringField(）simple.PasswordField()

StringField/PasswordField 开始实例化 (提到实例化就应该想到：指定元类的 __call__、自己 / 父类的 __new__、__init__)：

StringField/PasswordField 是默认元类，自己没有 __new__ 和 __init__ 方法；

但父类 Field 类中有 __new__ 方法，所以执行父类的 __new__（Field.__new__）返回 UnboundField 对象

 
def new(cls, *args, **kwargs):#执行 __new__ 方法
if '_form' in kwargs and '_name' in kwargs:
return super(Field, cls).new(cls)
else:
#我 x 没想到 ! __new__ 既然返回了 1 个 UnboundField() 而不是 StringField/PasswordField 对象；狸猫换了太子 ？
return UnboundField(cls, *args, **kwargs)

Field.__new__（）

由于 Field.__new__ 方法返回了 1 个 UnboundField 对象，来看 UnboundField 的 __init__ 方法

class UnboundField(object):
    _formfield = True
    creation_counter = 0                   #静态字段 设置计数器
<span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__init__</span>(self, field_class, *args, **kwargs): <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">field_class=.StringField / PasswordField</span>
                                                 <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">获取到field_class 的 参数封装到 UnboundField对象中，并且设置 排序  'creation_counter': 2</span>


        UnboundField.creation_counter += 1              #每实例化 1 个 UnboundField 对象 计数器 +1
        self.field_class = field_class
        self.args = args
        self.kwargs = kwargs                #{'label': '用户名', 'validators': [<wtforms.validators.DataRequired object at 0x00000000038EF080>, <wtforms.validators.Length object at 0x00000000038EF0F0>], 'widget': <wtforms.widgets.core.TextInput object at 0x00000000038EF0B8>, 'render_kw': {'class': 'form-control'}}
        self.creation_counter = UnboundField.creation_counter#

        '''
        print(self.__dict__)  
        {
         'field_class': <class 'wtforms.fields.simple.PasswordField'>,
         'args': (),
         'kwargs': {'label': '密码', 'validators': [<wtforms.validators.DataRequired object at 0x00000000038EF198>, <wtforms.validators.Length object at 0x00000000038EF1D0>, <wtforms.validators.Regexp object at 0x00000000038EF208>], 'widget': <wtforms.widgets.core.PasswordInput object at 0x00000000038EF2B0>,
         'render_kw': {'class': 'form-control'}},
          'creation_counter': 2
          }
    </span><span style="color: rgba(128, 0, 0, 1)">'''</span></pre>

UnboundField.__init__

UnboundField 的 __init__ 方法在 UnboundField 对象中封装了 Field 类的参数和计数器，所以现在 LoginForml 类中封装数据如下

"""
print(LoginForm.__dict__)
LoginForm ={
    '__module__': '__main__', 
    'name': <1 UnboundField(StringField, (),{'creation_counter': 1, 'label': '用户名', 'validators': [<wtforms.validators.DataRequired object at 0x00000000037DAEB8>, <wtforms.validators.Length object at 0x000000000382B048>], 'widget': <wtforms.widgets.core.TextInput object at 0x000000000382B080>, 'render_kw': {'class': 'form-control'}  })>, 
    'pwd': <2 UnboundField(PasswordField, (),{'creation_counter': 2,'label': '密码', 'validators': [<wtforms.validators.DataRequired object at 0x000000000382B0F0>, <wtforms.validators.Length object at 0x000000000382B128>, <wtforms.validators.Regexp object at 0x000000000382B160>], 'widget': <wtforms.widgets.core.PasswordInput object at 0x000000000382B208>, 'render_kw': {'class': 'form-control'}})>, 
    '__doc__': None, 
    '_unbound_fields': None, 
    '_wtforms_meta': None,
}
"""

启发：

不一定要把代码都写在当前类中，如过多个类和类之间有同性方法、属性可以抽出来集中到父类之中；子类继承父类所以子类实例化对象之后，继承享有 2 者的属性和方法；所以看源码遇到继承一点要注意观察父类；

每个对象实例化（在排除 MetaClass 的情况下）都会执行父类的 __new__ 方法，再去执行 __init__ 方法；而 __new__ 实质性决定了实例化出来的对象是神马？

class Queen(object):
    def __new__(cls, *args, **kwargs):  #类中 __new__ 方法决定了类（），实例化出什么对象；
        return Cat('狸猫','男','太子')
</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__init__</span>(self,name):           <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">由于__nwe__方法返回了其他对象，所以不会执行Queen的__init__方法</span>
    <span style="color: rgba(0, 0, 255, 1)">print</span>(<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">ok</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)
    self.name</span>=<span style="color: rgba(0, 0, 0, 1)">name

Prince=Queen('王子')
print(Prince.name)
print(Prince.gender)
print(Prince.identity)

狸猫换太子

2.LoginForm 实例化

谈到类实例化应该先检查该类是否指定了 Meta 类，如果指定了 Meta 类，就需要先执行（指定元类的 __call__、自己 / 父类的 __new__、__init__)

21. 执行 FormMeta 的 __call__ 方法，赋值 LoginForm 的 _unbound_fields 和 _wtforms_meta 属性；

根据 unbound 对象的 creation_counter 属性对 LoginForm 中的字段进行排序，并填充到 LoginForm 的 _unbound_fields 属性中

根据 LoginForm 的 __mro__ 继承顺序：获取当前类（FormLogin）所有父类, 并在每个父类中提取 Meta 属性添加到列表，转成元组，最后创建 Meta 类让其继承，赋值 LoginForm._wtforms_meta 属性

 def __call__(cls, *args, **kwargs):
        if cls._unbound_fields is None:      #在创建类时 已经设置 LoginForm 的 _unbound_fields 为空
            fields = []
                                                # 获取 LoginForm 类中，中所有属性的 key：['_get_translations', '_unbound_fields', '_wtforms_met,'name','populate_obj','process','pwd','validate'.....]
            for name in dir(cls):
                if not name.startswith('_'):   #排除 __ 下划线的私有属性 name. pwd
                    unbound_field = getattr(cls, name) #cls =LoginForm 类 #根据 key 获取 unbound_field 对象
                    if hasattr(unbound_field, '_formfield'): #检查 unbound_field 对象是否包含 _formfield = True
                        fields.append((name, unbound_field))
            # '''
            # fields = [
            #     (name,name 的 unbound 对象),
            #     (pwd,pwd 的 unbound 对象),
            #             ]
            # '''
            #对 fields 按照定义顺序 进行排序
            fields.sort(key=lambda x: (x[1].creation_counter, x[0]))  #根据 unbound 对象的 creation_counter 进行字段排序
            cls._unbound_fields = fields
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> cls._wtforms_meta <span style="color: rgba(0, 0, 255, 1)">is</span><span style="color: rgba(0, 0, 0, 1)"> None:
        bases </span>= [] <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">bases = [DefaultMeta],</span>
        <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 按照继承顺序：获取当前类（FormLogin）所有父类</span>
        <span style="color: rgba(0, 0, 255, 1)">for</span> mro_class <span style="color: rgba(0, 0, 255, 1)">in</span> cls.<span style="color: rgba(128, 0, 128, 1)">__mro__</span><span style="color: rgba(0, 0, 0, 1)">:
            </span><span style="color: rgba(0, 0, 255, 1)">if</span> <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Meta</span><span style="color: rgba(128, 0, 0, 1)">'</span> <span style="color: rgba(0, 0, 255, 1)">in</span> mro_class.<span style="color: rgba(128, 0, 128, 1)">__dict__</span>:  <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">去每个父类（mro_class）获取  Meta = DefaultMeta</span>


                bases.append(mro_class.Meta)    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">bases = [DefaultMeta],</span>

                <span style="color: rgba(128, 0, 0, 1)">'''</span><span style="color: rgba(128, 0, 0, 1)">
                class Meta(DefaultMeta):
                    pass 
            </span><span style="color: rgba(128, 0, 0, 1)">'''</span><span style="color: rgba(0, 0, 0, 1)">
        cls._wtforms_meta </span>= type(<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">Meta</span><span style="color: rgba(128, 0, 0, 1)">'</span>, tuple(bases), {}) <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">cls._wtforms_meta=Meta(DefaultMeta)类:</span>

    <span style="color: rgba(0, 0, 255, 1)">return</span> type.<span style="color: rgba(128, 0, 128, 1)">__call__</span>(cls, *args, **kwargs)</pre>

FormMeta.__call__

执行完了指定元类 FormMeta.__call__() 方法之后的 LoginForm 类中封装的数据

print(LoginForm.__dict__)
LoginForm ={
    '__module__': '__main__', 
    'name': <1 UnboundField(StringField, (),{'creation_counter': 1, 'label': '用户名', 'validators': [<wtforms.validators.DataRequired object at 0x00000000037DAEB8>, <wtforms.validators.Length object at 0x000000000382B048>], 'widget': <wtforms.widgets.core.TextInput object at 0x000000000382B080>, 'render_kw': {'class': 'form-control'}  })>, 
    'pwd': <2 UnboundField(PasswordField, (),{'creation_counter': 2,'label': '密码', 'validators': [<wtforms.validators.DataRequired object at 0x000000000382B0F0>, <wtforms.validators.Length object at 0x000000000382B128>, <wtforms.validators.Regexp object at 0x000000000382B160>], 'widget': <wtforms.widgets.core.PasswordInput object at 0x000000000382B208>, 'render_kw': {'class': 'form-control'}})>, 
    '__doc__': None, 
</span><span style="color: rgba(255, 0, 0, 1)">'_unbound_fields': [
            (name, UnboundField对象（1，simple.StringField，参数）)，
            (pwd, UnboundField对象（2，simple.PasswordField，参数）)，
        ],, 
'_wtforms_meta': Meta(DefaultMeta)类,

}
"""

启发：

#sort 排序
v1=[
    (11,'Martin11',18),
    (121,'Martin121',19),
    (311,'Martin311',25),
    (311, 'Martin311', 26)  #按元素 1 排序，如果元素 1 相同按照 元素 3 排序
]
v1.sort(key=lambda x:(x[0],x[2])) #列表的 sort 方法，根据 列表中的元组元素 进行排序
print(v1)
'''
[(11, 'Martin11', 18), (121, 'Martin121', 19), (311, 'Martin311', 25), (311, 'Martin311', 26)]
'''

列表的 sort（）

class F1(object):
    pass
class F2(object):
    pass
class F3(F1):
    pass
class F4(F2,F3):
pass
print(F4.mro) #打印 F4 的继承关系
'''
(
<class 'main.F4'>,
<class 'main.F2'>,
<class 'main.F3'>,
<class 'main.F1'>,
<class 'object'>)
'''

__mro__ 获取当前对象的继承顺序

2.2. 执行 LoginForm 的 __new__ 方法

没有 __new__ 方法 pass

2.3. 执行 LoginForm 的 __init__ 方法实例化 form 对象

    def __init__(self, formdata=None, obj=None, prefix='', data=None, meta=None, **kwargs):
    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 实例化LoginForm中封装的 Meta类进行实例化，以后用于生成CSRF Tocken 标签</span>
    meta_obj =<span style="color: rgba(0, 0, 0, 1)"> self._wtforms_meta()
    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">meta是 form = LoginForm(meta={'csrf':'true'})传过来的参数,封装到meta_obj中</span>
    <span style="color: rgba(0, 0, 255, 1)">if</span> meta <span style="color: rgba(0, 0, 255, 1)">is</span> <span style="color: rgba(0, 0, 255, 1)">not</span> None <span style="color: rgba(0, 0, 255, 1)">and</span><span style="color: rgba(0, 0, 0, 1)"> isinstance(meta, dict):
        meta_obj.update_values(meta)

    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">执行父类的构造方法,参数</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> self._unbound_fields</span>
    <span style="color: rgba(128, 0, 0, 1)">'''</span><span style="color: rgba(128, 0, 0, 1)">
        '_unbound_fields'=[
            (name, UnboundField对象（1，simple.StringField，参数）)，
            (pwd, UnboundField对象（2，simple.PasswordField，参数）)，
        ],
    </span><span style="color: rgba(128, 0, 0, 1)">'''</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> meta_ob=Meta(DefaultMeta)对象</span>


        super(Form, self).__init__(self._unbound_fields, meta=meta_obj, prefix=prefix)
        #给 form 对象 中的 _fields 字段赋值如下；
        '''
        _fields: {name: StringField 对象 (),
                pwd: PasswordField 对象 (),}
        name:  StringField 对象 (widget=widgets.TextInput()),
        pwd:  PasswordField 对象 (widget=widgets.PasswordInput())
    </span><span style="color: rgba(128, 0, 0, 1)">'''</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">循环form对象 中的_fields字段（字典），给form对象赋值 form.name/form.pwd</span>
    <span style="color: rgba(0, 0, 255, 1)">for</span> name, field <span style="color: rgba(0, 0, 255, 1)">in</span><span style="color: rgba(0, 0, 0, 1)"> iteritems(self._fields):
        setattr(self, name, field)
    </span><span style="color: rgba(128, 0, 0, 1)">'''</span><span style="color: rgba(128, 0, 0, 1)">
     _fields: {
        name: StringField对象(),
        pwd: PasswordField对象(),
            }
     name:  StringField对象(widget=widgets.TextInput()),
     
     pwd:  PasswordField对象(widget=widgets.PasswordInput())

       </span><span style="color: rgba(128, 0, 0, 1)">'''</span><span style="color: rgba(0, 0, 0, 1)">
    self.process(formdata, obj, data</span>=data, **kwargs)</pre>

Form.__init__

执行 Form 父类 BaseForm.__init__ 方法，把 UnboundField 对象转换成 StringField 对象，并赋值到 form 对象的 _fields:{} 字典中；

class BaseForm(object):
    def __init__(self, fields, prefix='', meta=DefaultMeta()):
        '''
        参数
            fields=[(name, UnboundField 对象（1，simple.StringField，参数）)，
                (pwd, UnboundField 对象（2，simple.PasswordField，参数）)，
            ]，
        meta=Meta(DefaultMeta)对象
    </span><span style="color: rgba(128, 0, 0, 1)">'''</span>

    <span style="color: rgba(0, 0, 255, 1)">if</span> prefix <span style="color: rgba(0, 0, 255, 1)">and</span> prefix[-1] <span style="color: rgba(0, 0, 255, 1)">not</span> <span style="color: rgba(0, 0, 255, 1)">in</span> <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">-_;:/.</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
        prefix </span>+= <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">-</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">

    self.meta </span>=<span style="color: rgba(0, 0, 0, 1)"> meta
    self._prefix </span>=<span style="color: rgba(0, 0, 0, 1)"> prefix
    self._errors </span>=<span style="color: rgba(0, 0, 0, 1)"> None
    self._fields </span>=<span style="color: rgba(0, 0, 0, 1)"> OrderedDict()

    </span><span style="color: rgba(0, 0, 255, 1)">if</span> hasattr(fields, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">items</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">):
        fields </span>=<span style="color: rgba(0, 0, 0, 1)"> fields.items()

    translations </span>=<span style="color: rgba(0, 0, 0, 1)"> self._get_translations()
    extra_fields </span>=<span style="color: rgba(0, 0, 0, 1)"> []
    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">------------------------------------------------------</span>
    <span style="color: rgba(0, 0, 255, 1)">if</span> meta.csrf: <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">生成 CSRF tocken隐藏标签</span>
        self._csrf =<span style="color: rgba(0, 0, 0, 1)"> meta.build_csrf(self)
        extra_fields.extend(self._csrf.setup_form(self))

    </span><span style="color: rgba(0, 0, 255, 1)">for</span> name, unbound_field <span style="color: rgba(0, 0, 255, 1)">in</span> itertools.chain(fields, extra_fields):<span style="color: rgba(0, 128, 0, 1)">#

            #(name, UnboundField 对象（1，simple.StringField，参数）)
#(pwd, UnboundField 对象（2，simple.PasswordField，参数）)
options = dict(name=name, prefix=prefix, translations=translations)
#(name, UnboundField 对象（1，simple.StringField，参数）)  #真正实例化 simple.StringField(参数)
field = meta.bind_field(self, unbound_field, options)
#UnboundField 对象转换成 StringField 对象
self._fields[name] = field

BaseForm. __init__

 form = {
        _fields: {name: StringField 对象 (),
                pwd: PasswordField 对象 (),}


循环 form 对象 中的 _fields 字段（字典），分别赋值到 form 对象，这样就可以通过 form.name/form.pwd 直接获取到 Field 对象了
，无需 form._fields['name'] / form._fields['name']


代码:

for name, field in iteritems(self._fields):
    setattr(self, name, field)


　　　　　　　　　　　　　　　　　　　　　　　　form 对象封装数据就变成以下内容喽

 
form = {
        _fields: {name: StringField 对象 (),
                pwd: PasswordField 对象 (),}
        name:  StringField 对象 (widget=widgets.TextInput()),
        pwd:  PasswordField 对象 (widget=widgets.PasswordInput())
    
        }

3. 当 form 对象生成之后 print(form.name) = 执行StringField 对象的 __str__ 方法；

StringField 类中没有 __str__ 方法，所以去执行基类 Field 的，Field.__str__ 方法返回了： self() = StringFieldObj.__call__()

 def __str__(self):
        return self() #执行 LoginForm 的 __call__ 方法

Field.__str__ 方法

StringField 没有 __call__ 所以执行其基类 Field.__call__ 方法，调用了 self.meta.render_field(self, kwargs)

    def __call__(self, **kwargs): 　　　　　　　　　　　# self=StringField 对象
        return self.meta.render_field(self, kwargs) #把 StringField 对象传传入 meta.render_field 方法

下面来看 self.meta.render_field(self, kwargs) 做了什么？

  def render_field(self, field, render_kw):
    other_kw </span>= getattr(field, <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">render_kw</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">, None)
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> other_kw <span style="color: rgba(0, 0, 255, 1)">is</span> <span style="color: rgba(0, 0, 255, 1)">not</span><span style="color: rgba(0, 0, 0, 1)"> None:
        render_kw </span>= dict(other_kw, **<span style="color: rgba(0, 0, 0, 1)">render_kw)
    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> StringField对象.widget(field, **render_kw)</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)">插件.__call__()</span>
    <span style="color: rgba(128, 0, 0, 1)">'''</span><span style="color: rgba(128, 0, 0, 1)">
    #field =StringField对象
       StringField对象.widget对象()=调用widget对象的.__call__方法
    </span><span style="color: rgba(128, 0, 0, 1)">'''</span>
    <span style="color: rgba(0, 0, 255, 1)">return</span> field.widget(field, **render_kw)</pre>

来看 widget 对象 =TextInput() 的 __call__ 方法，最终打印了 obj.name 的结果

  def __call__(self, field, **kwargs):
        kwargs.setdefault('id', field.id)
        kwargs.setdefault('type', self.input_type)
        if 'value' not in kwargs:
            kwargs['value'] = field._value()
        if 'required' not in kwargs and 'required' in getattr(field, 'flags', []):
            kwargs['required'] = True
        return HTMLString('<input %s>' % self.html_params(name=field.name, **kwargs))

   """
        0. Form.__iter__: 返回所有字段对象
            1. StringField 对象.__str__
            2. StringField 对象.__call__
            3. meta.render_field(StringField 对象,)
            4. StringField 对象.widget(field, **render_kw)
            5. 插件.__call__()
        """

4. 执行 for iteam in form 对象的执行流程

执行 form 对象基类 BaseForm 的 __inter__ 方法，变量 self._fields 字典中的内容

def __iter__(self):
        """Iterate form fields in creation order."""
        return iter(itervalues(self._fields))

_fields: {name: StringField 对象 (),
                pwd: PasswordField 对象 (),}

用户输入数据的校验验证流程 form = LoginForm(formdata=request.form)

        # 请求发过来的值
        form = LoginForm(formdata=request.form) # 值.getlist('name')
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> 实例：编辑</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> # 从数据库对象</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> form = LoginForm(obj='值') # 值.name/值.pwd</span>
    <span style="color: rgba(0, 128, 0, 1)">#

        # # 字典 {}
# form = LoginForm(data=request.form) # 值 ['name']
       # 1. 循环所有的字段
# 2. 获取每个字段的钩子函数
# 3. 为每个字段执行他的验证流程 字段.validate(钩子函数 + 内置验证规则)

六、session 功能

1. Flask 自带的 session 功能

from flask import session
import json
app=Flask(__name__,template_folder='templates',static_path='/static/',static_url_path='/static/')
app.debug=True
app.secret_key='sjehfjeefrjewth43u'  #设置 session 加密
app.config['JSON_AS_ASCII']=False  #指定 json 编码格式 如果为 False 就不使用 ascii 编码，
app.config['JSONIFY_MIMETYPE'] ="application/json;charset=utf-8" #指定浏览器渲染的文件类型，和解码格式；

@app.route('/login/',methods=['GET','POST'])
def login():
    msg = ''
    if request.method=='POST':
        name=request.values.get('user')
        pwd=request.values.get('pwd')
        if name =='zhanggen' and pwd=='123.com':
            session['user']=name  #设置 session 的 key value
            return redirect('/index/')
        else:
            msg='用户名或者密码错误'
    return render_template('login.html',msg=msg)
@app.route('/index/',methods=['GET','POST'])
def index():
user_list = ['张根', 'egon', 'eric']
user=session.get('user')           #获取 session
if user:
user=['alex','egon','eric']
return jsonify(user_list)
else:
return redirect('/login/')
if name == 'main':
app.run()

Flask 自带 session 功能

2. 第三方 session 组件（Session）

安装 pip install flask-session

from flask import session, Flask,request,make_response,render_template,redirect,jsonify,Response
from flask.ext.session import Session #引入第三方 session
import json
app=Flask(name,template_folder='templates',static_path='/static/',static_url_path='/static/')
app.debug=True
app.secret_key='sjehfjeefrjewth43u'  #设置 session 加密
app.config['JSON_AS_ASCII']=False  #指定 json 编码格式 如果为 False 就不使用 ascii 编码，
app.config['JSONIFY_MIMETYPE'] ="application/json;charset=utf-8" #指定浏览器渲染的文件类型，和解码格式；

app.config['SESSION_TYPE']='redis'
from redis import Redis        #引入连接 redis 模块
app.config['SESSION_REDIS']=Redis(host='192.168.0.94',port=6379) #连接 redis
Session(app)
@app.route('/login/',methods=['GET','POST'])
def login():
msg = ''
if request.method=='POST':
name=request.values.get('user')
pwd=request.values.get('pwd')
if name =='zhanggen' and pwd=='123.com':
session['user']=name  #设置 session 的 key value
return redirect('/index/')
else:
msg='用户名或者密码错误'
return render_template('login.html',msg=msg)
@app.route('/index/',methods=['GET','POST'])
def index():
user_list = ['张根', 'egon', 'eric']
user=session.get('user')           #获取 session
if user:
user=['alex','egon','eric']
return jsonify(user_list)
else:
return redirect('/login/')
if name == 'main':
app.run()

把 session 存到 redis

不仅可以把 session 存放到 redis 还可放到文件、内存、memcache...

    def _get_interface(self, app):
        config = app.config.copy()
        config.setdefault('SESSION_TYPE', 'null')
        config.setdefault('SESSION_PERMANENT', True)
        config.setdefault('SESSION_USE_SIGNER', False)
        config.setdefault('SESSION_KEY_PREFIX', 'session:')
        config.setdefault('SESSION_REDIS', None)
        config.setdefault('SESSION_MEMCACHED', None)
        config.setdefault('SESSION_FILE_DIR',
                          os.path.join(os.getcwd(), 'flask_session'))
        config.setdefault('SESSION_FILE_THRESHOLD', 500)
        config.setdefault('SESSION_FILE_MODE', 384)
        config.setdefault('SESSION_MONGODB', None)
        config.setdefault('SESSION_MONGODB_DB', 'flask_session')
        config.setdefault('SESSION_MONGODB_COLLECT', 'sessions')
        config.setdefault('SESSION_SQLALCHEMY', None)
        config.setdefault('SESSION_SQLALCHEMY_TABLE', 'sessions')
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_TYPE</span><span style="color: rgba(128, 0, 0, 1)">'</span>] == <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">redis</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
        session_interface </span>=<span style="color: rgba(0, 0, 0, 1)"> RedisSessionInterface(
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_REDIS</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_KEY_PREFIX</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_USE_SIGNER</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_PERMANENT</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">])
    </span><span style="color: rgba(0, 0, 255, 1)">elif</span> config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_TYPE</span><span style="color: rgba(128, 0, 0, 1)">'</span>] == <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">memcached</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
        session_interface </span>=<span style="color: rgba(0, 0, 0, 1)"> MemcachedSessionInterface(
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_MEMCACHED</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_KEY_PREFIX</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_USE_SIGNER</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_PERMANENT</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">])
    </span><span style="color: rgba(0, 0, 255, 1)">elif</span> config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_TYPE</span><span style="color: rgba(128, 0, 0, 1)">'</span>] == <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">filesystem</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
        session_interface </span>=<span style="color: rgba(0, 0, 0, 1)"> FileSystemSessionInterface(
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_FILE_DIR</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_FILE_THRESHOLD</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_FILE_MODE</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_KEY_PREFIX</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_USE_SIGNER</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_PERMANENT</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">])
    </span><span style="color: rgba(0, 0, 255, 1)">elif</span> config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_TYPE</span><span style="color: rgba(128, 0, 0, 1)">'</span>] == <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">mongodb</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
        session_interface </span>=<span style="color: rgba(0, 0, 0, 1)"> MongoDBSessionInterface(
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_MONGODB</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_MONGODB_DB</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_MONGODB_COLLECT</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_KEY_PREFIX</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_USE_SIGNER</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_PERMANENT</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">])
    </span><span style="color: rgba(0, 0, 255, 1)">elif</span> config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_TYPE</span><span style="color: rgba(128, 0, 0, 1)">'</span>] == <span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">sqlalchemy</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">:
        session_interface </span>=<span style="color: rgba(0, 0, 0, 1)"> SqlAlchemySessionInterface(
            app, config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_SQLALCHEMY</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_SQLALCHEMY_TABLE</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_KEY_PREFIX</span><span style="color: rgba(128, 0, 0, 1)">'</span>], config[<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_USE_SIGNER</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">],
            config[</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">SESSION_PERMANENT</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">])
    </span><span style="color: rgba(0, 0, 255, 1)">else</span><span style="color: rgba(0, 0, 0, 1)">:
        session_interface </span>=<span style="color: rgba(0, 0, 0, 1)"> NullSessionInterface()

    </span><span style="color: rgba(0, 0, 255, 1)">return</span> session_interface</pre>

View Code

3. 自定义 session 组件

#!/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 ())
</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__setitem__</span><span style="color: rgba(0, 0, 0, 1)">(self, key, value):
    super(MySession, self).</span><span style="color: rgba(128, 0, 128, 1)">__setitem__</span><span style="color: rgba(0, 0, 0, 1)">(key, value)

</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__getitem__</span><span style="color: rgba(0, 0, 0, 1)">(self, item):
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> super(MySession, self).<span style="color: rgba(128, 0, 128, 1)">__getitem__</span><span style="color: rgba(0, 0, 0, 1)">(item)

</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__delitem__</span><span style="color: rgba(0, 0, 0, 1)">(self, key):
    super(MySession, self).</span><span style="color: rgba(128, 0, 128, 1)">__delitem__</span><span style="color: rgba(0, 0, 0, 1)">(key)

class MySessionInterface(SessionInterface):
session_class = MySession
container = {}
</span><span style="color: rgba(0, 0, 255, 1)">def</span> <span style="color: rgba(128, 0, 128, 1)">__init__</span><span style="color: rgba(0, 0, 0, 1)">(self):
    </span><span style="color: rgba(0, 0, 255, 1)">import</span><span style="color: rgba(0, 0, 0, 1)"> redis
    self.redis </span>=<span style="color: rgba(0, 0, 0, 1)"> redis.Redis()

</span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> _generate_sid(self):
    </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> str(uuid.uuid4())

</span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> _get_signer(self, app):
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> <span style="color: rgba(0, 0, 255, 1)">not</span><span style="color: rgba(0, 0, 0, 1)"> app.secret_key:
        </span><span style="color: rgba(0, 0, 255, 1)">return</span><span style="color: rgba(0, 0, 0, 1)"> None
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> Signer(app.secret_key, salt=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">flask-session</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">,
                  key_derivation</span>=<span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(128, 0, 0, 1)">hmac</span><span style="color: rgba(128, 0, 0, 1)">'</span><span style="color: rgba(0, 0, 0, 1)">)

</span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> open_session(self, app, request):
    </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(128, 0, 0, 1)">
    程序刚启动时执行，需要返回一个session对象
    </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(0, 0, 0, 1)">
    sid </span>=<span style="color: rgba(0, 0, 0, 1)"> request.cookies.get(app.session_cookie_name)
    </span><span style="color: rgba(0, 0, 255, 1)">if</span> <span style="color: rgba(0, 0, 255, 1)">not</span><span style="color: rgba(0, 0, 0, 1)"> sid:
        sid </span>=<span style="color: rgba(0, 0, 0, 1)"> self._generate_sid()
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> self.session_class(sid=<span style="color: rgba(0, 0, 0, 1)">sid)

    signer </span>=<span style="color: rgba(0, 0, 0, 1)"> self._get_signer(app)
    </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">:
        sid_as_bytes </span>=<span style="color: rgba(0, 0, 0, 1)"> signer.unsign(sid)
        sid </span>=<span style="color: rgba(0, 0, 0, 1)"> sid_as_bytes.decode()
    </span><span style="color: rgba(0, 0, 255, 1)">except</span><span style="color: rgba(0, 0, 0, 1)"> BadSignature:
        sid </span>=<span style="color: rgba(0, 0, 0, 1)"> self._generate_sid()
        </span><span style="color: rgba(0, 0, 255, 1)">return</span> self.session_class(sid=<span style="color: rgba(0, 0, 0, 1)">sid)

    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> session保存在redis中</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> val = self.redis.get(sid)</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> session保存在内存中</span>
    val =<span style="color: rgba(0, 0, 0, 1)"> self.container.get(sid)

    </span><span style="color: rgba(0, 0, 255, 1)">if</span> val <span style="color: rgba(0, 0, 255, 1)">is</span> <span style="color: rgba(0, 0, 255, 1)">not</span><span style="color: rgba(0, 0, 0, 1)"> None:
        </span><span style="color: rgba(0, 0, 255, 1)">try</span><span style="color: rgba(0, 0, 0, 1)">:
            data </span>=<span style="color: rgba(0, 0, 0, 1)"> json.loads(val)
            </span><span style="color: rgba(0, 0, 255, 1)">return</span> self.session_class(data, sid=<span style="color: rgba(0, 0, 0, 1)">sid)
        </span><span style="color: rgba(0, 0, 255, 1)">except</span><span style="color: rgba(0, 0, 0, 1)">:
            </span><span style="color: rgba(0, 0, 255, 1)">return</span> self.session_class(sid=<span style="color: rgba(0, 0, 0, 1)">sid)
    </span><span style="color: rgba(0, 0, 255, 1)">return</span> self.session_class(sid=<span style="color: rgba(0, 0, 0, 1)">sid)

</span><span style="color: rgba(0, 0, 255, 1)">def</span><span style="color: rgba(0, 0, 0, 1)"> save_session(self, app, session, response):
    </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(128, 0, 0, 1)">
    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
    </span><span style="color: rgba(128, 0, 0, 1)">"""</span><span style="color: rgba(0, 0, 0, 1)">
    domain </span>=<span style="color: rgba(0, 0, 0, 1)"> self.get_cookie_domain(app)
    path </span>=<span style="color: rgba(0, 0, 0, 1)"> self.get_cookie_path(app)
    httponly </span>=<span style="color: rgba(0, 0, 0, 1)"> self.get_cookie_httponly(app)
    secure </span>=<span style="color: rgba(0, 0, 0, 1)"> self.get_cookie_secure(app)
    expires </span>=<span style="color: rgba(0, 0, 0, 1)"> self.get_expiration_time(app, session)

    val </span>=<span style="color: rgba(0, 0, 0, 1)"> json.dumps(dict(session))

    </span><span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> session保存在redis中</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> self.redis.setex(name=session.sid, value=val, time=app.permanent_session_lifetime)</span>
    <span style="color: rgba(0, 128, 0, 1)">#</span><span style="color: rgba(0, 128, 0, 1)"> session保存在内存中</span>

        self.container.setdefault(session.sid, val)
    session_id </span>=<span style="color: rgba(0, 0, 0, 1)"> self._get_signer(app).sign(want_bytes(session.sid))

    response.set_cookie(app.session_cookie_name, session_id,
                        expires</span>=expires, httponly=<span style="color: rgba(0, 0, 0, 1)">httponly,
                        domain</span>=domain, path=path, secure=secure)</pre>

组件

from flask import Flask
from flask import session
from my_session import MySessionInterface
app = Flask(name)
app.secret_key = 'A0Zr98j/3yX R~XHH!jmN]LWX/,?RT'
app.session_interface = MySessionInterface()
@app.route('/login/', methods=['GET', "POST"])
def login():
print(session)
session['user1'] = 'alex'
session['user2'] = 'alex'
del session['user2']
</span><span style="color: rgba(0, 0, 255, 1)">return</span> <span style="color: rgba(128, 0, 0, 1)">"</span><span style="color: rgba(128, 0, 0, 1)">内容</span><span style="color: rgba(128, 0, 0, 1)">"</span>

if name == 'main':
app.run()

应用

七、蓝图

from flask import Blueprint

Flask 的 Blueprint 功能称为蓝图，它的功能就像Django 中的 include 或者 Gin 的路由分组，旨在为 web 框架的路由进行合理拆分。

from flask import Blueprint
#把名称为 test_zhanggen 的蓝图 register 到 app 中
test_zhanggen= Blueprint('oss_api_zhanggen',__name__)
@test_zhanggen.route('/index/', methods=['GET', 'POST'])
def index():
    """功能项辅助审核"""
    return "测试 / 张根 /Index"
@test_zhanggen.route('/home/', methods=['GET', 'POST'])
def home():
"""功能项辅助审核"""
return "测试 / 张根 /Home"

在 app 注册已经生成的蓝图

#把 api_zhanggen 文件中 test_zhanggen 蓝图注册到 flask appp
app.register_blueprint(blueprint=api_zhanggen.test_zhanggen, url_prefix='/test/zhanggen')

八、message （闪现）

message 是一个基于 Session 实现的用于保存数据的集合，其特点是：一次性。

特点：和 labada 匿名函数一样不长期占用内存

from flask import Flask,request,flash,get_flashed_messages
app = Flask(name)
app.secret_key = 'some_secret'
@app.route('/set/')
def index2():
flash('Disposable')    #在 message 中设置 1 个个值
return 'ok'
#---------------------------------------------------------------------------------

@app.route('/')
def index1():
messages = get_flashed_messages() #获取 message 中设置的值，只能获取 1 次。（1 次性）
print(messages)
return "Index1"
if name == "main":
app.run()

flask_message

九、中间件

flask 也有中间件功能和 Django 类似，不同的是使用的是使用 3 个装饰器来实现的；

1.@app.before_first_request : 请求第 1 次到来执行 1 次，之后都不执行；

2.@app.before_request：请求到达视图之前执行；（改函数不能有返回值，否则直接在当前返回）

3.@app.after_request：请求经过视图之后执行；（最下面的先执行）

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask, Request, render_template
app = Flask(name, template_folder='templates')
app.debug = True
@app.before_first_request  #第 1 个请求到来执行
def before_first_request1():
print('before_first_request1')
@app.before_request #中间件 2
def before_request1():
Request.nnn = 123
print('before_request1')  #不能有返回值，一旦有返回值在当前返回

@app.before_request
def before_request2():
print('before_request2')
@app.errorhandler(404)
def page_not_found(error):
return 'This page does not exist', 404
@app.route('/')
def hello_world():
return "Hello World"
@app.after_request #中间件 执行视图之后
def after_request1(response):
print('after_request1', response)
return response
@app.after_request #中间件 执行视图之后 先执行 after_request2
def after_request2(response):
print('after_request2', response)
return response
if name == 'main':
app.run()

View Code

十、Flask 相关组件

1、flask-sqlchemy

2、flask-script 组件

flask-script 组件：用于通过脚本的形式，启动 flask；（实现类似 Django 的 python manager.py runserver 0.0.0.0:8001)

pip install flask-script        #安装

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from sansa import create_app
from flask_script import Manager #导入
app = create_app()
manager=Manager(app)              #实例化 Manager 对象
if name == 'main':
manager.run()

run.py

python run.py runserver -h 0.0.0.0 -p 8001

* Running on http://0.0.0.0:8001/ (Press CTRL+C to quit)

3.flask-migrate 组件

在线修改、迁移数据库（Django 的 migrate 。

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from sansa import create_app,db
from flask_script import Manager #导入
from flask_migrate import  Migrate,MigrateCommand
app = create_app()
manager=Manager(app)              #实例化 Manager 对象
migrate=Migrate(app,db)
manager.add_command('db',MigrateCommand) #注册命令
if name == 'main':
manager.run()

run.py

pip install flask-migrate       #安装

3.1. 初始化数据库：python run.py db init

3.2. 迁移数据： python run.py db migrate

3.3. 生成表： python run.py db upgrade

ps: 修改表结构 first 直接注释静态字段代码，second 执行 python run.py db upgrade.

D:\Flask 练习 \sansa>python run.py db init
Creating directory D:\Flask 练习 \sansa\migrations ... done
Creating directory D:\Flask 练习 \sansa\migrations\versions ... done
Generating D:\Flask 练习 \sansa\migrations\alembic.ini ... done
Generating D:\Flask 练习 \sansa\migrations\env.py ... done
Generating D:\Flask 练习 \sansa\migrations\README ... done
Generating D:\Flask 练习 \sansa\migrations\script.py.mako ... done
Please edit configuration/connection/logging settings in 'D:\\Flask 练习 \\sansa\\migrations\\alembic.ini' before proceeding.
D:\Flask 练习 \sansa>python run.py db migrate
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'users666'
Generating D:\Flask 练习 \sansa\migrations\versions\a7f412a8146f_.py ... done
D:\Flask 练习 \sansa>python run.py db upgrade
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> a7f412a8146f, empty message
D:\Flask 练习 \sansa>

文档： http://docs.jinkan.org/docs/flask/quickstart.html

银角大王：http://www.cnblogs.com/wupeiqi/articles/7552008.html

银角大王：http://www.cnblogs.com/wupeiqi/articles/5713330.html（执行原生 SQL 模块 pymsql ，ORM 框架 SQLAchemy）

PythonWEB框架之Flask

前言：

Flask 简单使用

一、配置文件

二、路由系统

四、视图

五、模板语言

六、session 功能

七、蓝图

八、message （闪现）

九、中间件

十、Flask 相关组件

相关帖子

随便看看

PythonWEB框架之Flask