Python Web开发之Flask

前言:

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的第三方开源组件比丰富;http://flask.pocoo.org/extensions/

Bottle:比较简单;

总结:

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;

Flask的socket是基于Werkzeug 实现的,模板语言依赖jinja2模板,在使用Flask之前需要安装一下;

pip3 install flask #安装flask
from werkzeug.wrappers import Request, Response # Flask的socket使用werkzeug实现,所以要导入 werkzeug@Request.application
def hellow(request):return Response('Hello World')
if__name__ == '__main__':from werkzeug.serving import run_simple run_simple('localhost',400,hellow)

werkzeug

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

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/zhanggendef 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urlfrom flask import Flask,url_forapp=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_forfrom werkzeug.routing import BaseConverter
app = Flask(import_name=__name__)
class RegexConverter(BaseConverter):""" 自定义URL匹配正则表达式"""def__init__(self, map, regex): super(RegexConverter, self).__init__(map) self.regex = regex
def to_python(self, value):""" 路由匹配时,匹配成功后传递给视图函数中参数的值 :param value: :return: """return int(value)
def to_url(self, value):""" 使用url_for反向生成URL时,传递的参数经过该方法处理,返回的值用于生成URL中的参数 :param value: :return: """ val = super(RegexConverter, self).to_url(value)return val
# 添加到flask中 app.url_map.converters['regex'] = RegexConverter
@app.route('/index/<regex("\d+"):nid>')def index(nid):print(url_for('index', nid='888'))return'Index'
if__name__ == '__main__': app.run()

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()

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
def get(self):return'Index.GET'def post(self):return'Index.POST'
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 -->

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>

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_tagdef 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_fifterdef 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, redirectfrom wtforms import Formfrom wtforms.fields import corefrom wtforms.fields import html5from wtforms.fields import simplefrom wtforms import validatorsfrom 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):
#不同的字段 内部包含正则表达式 html5.EmailField | html5.DateTimeField... name=simple.StringField( label='用户名', validators=[ #验证规则和错误提示信息 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(), #前端页面显示的插件.TextArea render_kw={'class': 'form-control'} #设置form标签的class信息 )
# 不同的字段 内部包含正则表达式 html5.EmailField | html5.DateTimeField... 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'),#自定义验证规则 validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{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() #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>
<!--<input type="password" name="pwd">--><p>{{form.pwd.label}} {{form.pwd}} {{form.pwd.errors[0] }}</p><input type="submit" value="提交"></form></body></html>
login.html

login.html

用户注册页面验证

#用户注册from flask import Flask, render_template, request, redirectfrom wtforms import Formfrom wtforms.fields import corefrom wtforms.fields import html5from wtforms.fields import simplefrom wtforms import validatorsfrom 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 = 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( #第二次输入密码 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") #验证2次输入的密码是否一致? ], 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'), #生成email input标签 render_kw={'class': 'form-control'} )
gender = core.RadioField( label='性别', choices=( #choice radio选项 (1, '男'), (2, '女'), ), coerce=int #讲用户提交过来的 '4' 强制转成 int 4 ) city = core.SelectField( label='城市', choices=( ('bj', '北京'), ('sh', '上海'), ) )
hobby = core.SelectMultipleField( #select 下拉框多选框 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), #生成Checkbox 多选框 option_widget=widgets.CheckboxInput(), coerce=int, default=[1, 2] )
def__init__(self, *args, **kwargs): #重写form验证类的__init__方法可以实时同步数据中数据 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): #wtforms验证 钩子函数""" 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': 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>

register.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

Python Web开发之Flask

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:

Python Web开发之Flask

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;

Python Web开发之Flask

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
def__str__(self): #调用插件的__str__return str(self.widget)
class DateField(object):def__init__(self, wg): self.widget = wg
def__str__(self):return 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,): passclass Form(NewBase): pass
class LoginForm(Form): pass'''
class Form(with_metaclass(FormMeta,BaseForm)):

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."""def__init__(cls, name, bases, attrs): type.__init__(cls, name, bases, attrs) #继承type的功能 cls._unbound_fields = None #在LoginForm中添加1个静态字段 cls._wtforms_meta = None #在LoginForm中添加1个静态字段

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
def__init__(self, field_class, *args, **kwargs): #field_class=.StringField / PasswordField#获取到field_class 的 参数封装到 UnboundField对象中,并且设置 排序 'creation_counter': 2 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 }'''

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')
def__init__(self,name): #由于__nwe__方法返回了其他对象,所以不会执行Queen的__init__方法print('ok') self.name=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):ifnot 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
if cls._wtforms_meta is None: bases = [] #bases = [DefaultMeta],# 按照继承顺序:获取当前类(FormLogin)所有父类for mro_class in cls.__mro__:if'Meta'in mro_class.__dict__: #去每个父类(mro_class)获取 Meta = DefaultMeta
bases.append(mro_class.Meta) #bases = [DefaultMeta],
''' class Meta(DefaultMeta): pass ''' cls._wtforms_meta = type('Meta', tuple(bases), {}) #cls._wtforms_meta=Meta(DefaultMeta)类:
return type.__call__(cls, *args, **kwargs)

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, '_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):passclass F2(object):passclass 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):
# 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 meta_obj = self._wtforms_meta()#meta是 form = LoginForm(meta={'csrf':'true'})传过来的参数,封装到meta_obj中if meta isnot None and isinstance(meta, dict): meta_obj.update_values(meta)
#执行父类的构造方法,参数# self._unbound_fields''' '_unbound_fields'=[ (name, UnboundField对象(1,simple.StringField,参数)), (pwd, UnboundField对象(2,simple.PasswordField,参数)), ],'''# meta_ob=Meta(DefaultMeta)对象 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())'''#循环form对象 中的_fields字段(字典),给form对象赋值 form.name/form.pwdfor name, field in iteritems(self._fields): setattr(self, name, field)''' _fields: { name: StringField对象(), pwd: PasswordField对象(), } name: StringField对象(widget=widgets.TextInput()), pwd: PasswordField对象(widget=widgets.PasswordInput())
''' self.process(formdata, obj, data=data, **kwargs)

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'''
if prefix and prefix[-1] notin'-_;:/.': prefix += '-'
self.meta = meta self._prefix = prefix self._errors = None self._fields = OrderedDict()
if hasattr(fields, 'items'): fields = fields.items()
translations = self._get_translations() extra_fields = []#------------------------------------------------------if meta.csrf: #生成 CSRF tocken隐藏标签 self._csrf = meta.build_csrf(self) extra_fields.extend(self._csrf.setup_form(self))
for name, unbound_field in itertools.chain(fields, extra_fields):##(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 = getattr(field, 'render_kw', None)if other_kw isnot None: render_kw = dict(other_kw, **render_kw)# StringField对象.widget(field, **render_kw)#插件.__call__()''' #field =StringField对象 StringField对象.widget对象()=调用widget对象的.__call__方法'''return field.widget(field, **render_kw)

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'notin kwargs: kwargs['value'] = field._value()if'required'notin kwargs and'required'in getattr(field, 'flags', []): kwargs['required'] = Truereturn 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')
# 实例:编辑# # 从数据库对象# form = LoginForm(obj='值') # 值.name/值.pwd## # 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 sessionimport jsonapp=Flask(__name__,template_folder='templates',static_path='/static/',static_url_path='/static/')app.debug=Trueapp.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 valuereturn 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sessionif 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sessionimport jsonapp=Flask(__name__,template_folder='templates',static_path='/static/',static_url_path='/static/')app.debug=Trueapp.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redisSession(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 valuereturn 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sessionif 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')
if config['SESSION_TYPE'] == 'redis': session_interface = RedisSessionInterface( config['SESSION_REDIS'], config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])elif config['SESSION_TYPE'] == 'memcached': session_interface = MemcachedSessionInterface( config['SESSION_MEMCACHED'], config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])elif config['SESSION_TYPE'] == 'filesystem': session_interface = FileSystemSessionInterface( config['SESSION_FILE_DIR'], config['SESSION_FILE_THRESHOLD'], config['SESSION_FILE_MODE'], config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])elif config['SESSION_TYPE'] == 'mongodb': session_interface = MongoDBSessionInterface( config['SESSION_MONGODB'], config['SESSION_MONGODB_DB'], config['SESSION_MONGODB_COLLECT'], config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])elif config['SESSION_TYPE'] == 'sqlalchemy': session_interface = SqlAlchemySessionInterface( app, config['SESSION_SQLALCHEMY'], config['SESSION_SQLALCHEMY_TABLE'], config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])else: session_interface = NullSessionInterface()
return session_interface

3.自定义session组件

#!/usr/bin/env python# -*- coding:utf-8 -*-import uuidimport jsonfrom flask.sessions import SessionInterfacefrom flask.sessions import SessionMixinfrom 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 ())
def__setitem__(self, key, value): super(MySession, self).__setitem__(key, value)
def__getitem__(self, item):return super(MySession, self).__getitem__(item)
def__delitem__(self, key): super(MySession, self).__delitem__(key)
class MySessionInterface(SessionInterface): session_class = MySession container = {}
def__init__(self):import redis self.redis = redis.Redis()
def _generate_sid(self):return str(uuid.uuid4())
def _get_signer(self, app):ifnot app.secret_key:return Nonereturn Signer(app.secret_key, salt='flask-session', key_derivation='hmac')
def open_session(self, app, request):""" 程序刚启动时执行,需要返回一个session对象""" sid = request.cookies.get(app.session_cookie_name)ifnot sid: sid = self._generate_sid()return self.session_class(sid=sid)
signer = self._get_signer(app)try: sid_as_bytes = signer.unsign(sid) sid = sid_as_bytes.decode()except BadSignature: sid = self._generate_sid()return self.session_class(sid=sid)
# session保存在redis中# val = self.redis.get(sid)# session保存在内存中 val = self.container.get(sid)
if val isnot None:try: data = json.loads(val)return self.session_class(data, sid=sid)except:return self.session_class(sid=sid)return self.session_class(sid=sid)
def save_session(self, app, session, response):""" 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""" domain = self.get_cookie_domain(app) path = self.get_cookie_path(app) httponly = self.get_cookie_httponly(app) secure = self.get_cookie_secure(app) expires = self.get_expiration_time(app, session)
val = json.dumps(dict(session))
# session保存在redis中# self.redis.setex(name=session.sid, value=val, time=app.permanent_session_lifetime)# session保存在内存中 self.container.setdefault(session.sid, val)
session_id = self._get_signer(app).sign(want_bytes(session.sid))
response.set_cookie(app.session_cookie_name, session_id, expires=expires, httponly=httponly, domain=domain, path=path, secure=secure)

组件

from flask import Flaskfrom flask import sessionfrom 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']
return"内容"
if__name__ == '__main__': app.run()

应用

 七、蓝图

使用Flask自带Blueprintmuk模块,帮助我们做代码目录结构的归类

Python Web开发之Flask

import luffy #导入luffy包就会执行luffy包中__init__.py文件luffy.app.run()

app.py

from flask import Flask
app=Flask(__name__,template_folder='templates',static_path='/static/',static_url_path='/static/')
app.debug=True
from .views import loginfrom .views import index
#把文件中蓝图对象注册到app里app.register_blueprint(login.login,url_prefix='/login') #访问login蓝图必须以url_prefix开头app.register_blueprint(index.index,url_prefix='/index')
if__name__ == '__main__': app.run()

luffy包的__init__.py

from flask import Blueprint #导入蓝图login=Blueprint('login',__name__) #在本模块实例化1个蓝图@login.route('/login/',methods=['GET','POST'])def login1():return'登录页面'

login

from flask import Blueprintindex=Blueprint('index',__name__)@index.route('/index/',methods=['GET','POST'])def index1():return'首页'

index

 

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2def before_request1(): Request.nnn = 123print('before_request1') #不能有返回值,一旦有返回值在当前返回
@app.before_requestdef 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_request2def after_request2(response):print('after_request2', response)return response
if__name__ == '__main__': app.run()

 

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_appfrom 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,dbfrom 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.

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)

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