内容简介：flask--Wtform
一、Wtform
WTForms是一个支持多个web框架的form组件，主要用于对用户请求数据进行验证。
安装：
pip3 install wtform
用途：
1. 用户登录注册
当用户登录时候，需要对用户提交的用户名和密码进行多种格式校验。如：
用户不能为空；用户长度必须大于6；
密码不能为空；密码长度必须大于12；密码必须包含 字母、数字、特殊字符等（自定义正则）；
#!/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')
app.debug = True
class LoginForm(Form):
name = simple.StringField(
label='用户名',
validators=[
validators.DataRequired(message='用户名不能为空.'),
validators.Length(min=6, max=18, message='用户名长度必须大于%(min)d且小于%(max)d')
],
widget=widgets.TextInput(),
render_kw={'class': 'form-control'}
)
pwd = simple.PasswordField(
label='密码',
validators=[
validators.DataRequired(message='密码不能为空.'),
validators.Length(min=8, message='用户名长度必须大于%(min)d'),
validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[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()
return render_template('login.html', form=form)
else:
form = LoginForm(formdata=request.form)
if form.validate():
print('用户提交数据通过格式验证，提交的值为：', form.data)
else:
print(form.errors)
return render_template('login.html', form=form)
if __name__ == '__main__':
app.run()
app.py
app.py
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<h1>登录</h1>
<form method="post">
<!--<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
2.用户注册
注册页面需要让用户输入：用户名、密码、密码重复、性别、爱好等。
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='alex'
)
pwd = simple.PasswordField(
label='密码',
validators=[
validators.DataRequired(message='密码不能为空.')
],
widget=widgets.PasswordInput(),
render_kw={'class': 'form-control'}
)
pwd_confirm = simple.PasswordField(
label='重复密码',
validators=[
validators.DataRequired(message='重复密码不能为空.'),
validators.EqualTo('pwd', message="两次密码输入不一致")
],
widget=widgets.PasswordInput(),
render_kw={'class': 'form-control'}
)
email = html5.EmailField(
label='邮箱',
validators=[
validators.DataRequired(message='邮箱不能为空.'),
validators.Email(message='邮箱格式错误')
],
widget=widgets.TextInput(input_type='email'),
render_kw={'class': 'form-control'}
)
gender = core.RadioField(
label='性别',
choices=(
(1, '男'),
(2, '女'),
),
coerce=int
)
city = core.SelectField(
label='城市',
choices=(
('bj', '北京'),
('sh', '上海'),
)
)
hobby = core.SelectMultipleField(
label='爱好',
choices=(
(1, '篮球'),
(2, '足球'),
),
coerce=int
)
favor = core.SelectMultipleField(
label='喜好',
choices=(
(1, '篮球'),
(2, '足球'),
),
widget=widgets.ListWidget(prefix_label=False),
option_widget=widgets.CheckboxInput(),
coerce=int,
default=[1, 2]
)
def __init__(self, *args, **kwargs):
super(RegisterForm, self).__init__(*args, **kwargs)
self.favor.choices = ((1, '篮球'), (2, '足球'), (3, '羽毛球'))
def validate_pwd_confirm(self, field):
"""
自定义pwd_confirm字段规则，例：与pwd字段是否一致
:param field:
:return:
"""
# 最开始初始化时，self.data中已经有所有的值
if field.data != self.data['pwd']:
# raise validators.ValidationError("密码不一致") # 继续后续验证
raise validators.StopValidation("密码不一致") # 不再继续后续验证
@app.route('/register', methods=['GET', 'POST'])
def register():
if request.method == 'GET':
form = RegisterForm(data={'gender': 1})
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()
APP.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
metaclass分析：
class MyType(type):
def __init__(self,*args,**kwargs):
print('xxxx')
super(MyType,self).__init__(*args,**kwargs)
def __call__(cls, *args, **kwargs):
obj = cls.__new__(cls,*args, **kwargs)
cls.__init__(obj,*args, **kwargs) # Foo.__init__(obj)
return obj
def with_metaclass(base):
return MyType("MyType",(base,),{})
class Foo(with_metaclass(object)):
def __init__(self,name):
self.name = name
class Form(with_metaclass(FormMeta, BaseForm)): #相当于给这个form类定义了一个makeclass,这个类在刚创建时，先执行makeclass,这行makeclass的__init__方法
pass
def with_metaclass(meta, base=object):
#meta=FormMeta(("NewBase", (BaseForm,), {})) #实例化了这个类
#base=BaseForm (base继承了BaseForm)
return meta("NewBase", (base,), {})
class LoginForm(Form): #当执行到这一句是，他在formdata这个类中，LoginForm这个类中 里边有（LoginForm._unbound_fields = None
LoginForm._wtforms_meta = None这两个字段）
name=simple.StringField( #name实例化一个StringField(如果这个name中有makeclass这个类先要执行makeclass这个类，一个类在实例化__init__之前 有__new__,__call__,type,这几个方法，
对一个类来说整个请求进来先执行type的__init__方法，实例化的时候先执行type的__call__方法，有type的__call__方法调用类的 __new__方法，然后在执行类的__init__方法，这才叫实例化完成。对与这个StringField类方法，
如果有__new__方法，先执行__new__方法，点击进去找到它的new方法，最开始写的是StringField但正真的最开始是name=UnboundField(cls, *args, **kwargs)
(name对应的是UnboundField)在这个UnboundField中封装creation_counter，它就等于当前creation_counter自加1)
label='用户名',
validators=[
validators.DataRequired(message='用户名不能为空'),
validators.Length(min=5,max=15,message='用户名的长度必须大于5且小于15')
],
widget=widgets.TextInput(),
render_kw={'class':'form-control'}
)
pwd=simple.PasswordField( #（在执行这个是pwd=UnboundField(cls, *args, **kwargs)但是当他执行时UnboundField中的creation_counter这个静态字段已经被更新，
用creation_counter这个来计数是因为跟你以后在页面上显示的次序有关系）
label='密码',
validators=[
validators.DataRequired(message='密码不能为空'),
validators.Length(min=6,max=15,message='密码的长度必须大于6且小于15')
],
widget=widgets.TextInput(),
render_kw={'class':'form-control'}
)
3.Wtform源码分析
form类
from wtforms import Form
字段功能：（ 1. 通过正则进行校验； 2 . 插件生成HTML标签 ）
from wtforms.fields import core
from wtforms.fields import html5 from wtforms.fields import simple
插件
from wtforms import widgets from wtforms import validators
源码：
代码刚开始运行时：先执行LoginForm这个类的字段开始实例化
LoginForm 继承From，这个类是有type创建 ,默认makeclass=type (makeclass可以自定义）
流程：
from flask import Flask,request,render_template,redirect
from wtforms import Form
from wtforms import widgets
from wtforms import validators
from wtforms.fields import core
from wtforms.fields import simple
from wtforms.fields import html5
app = Flask(__name__)
class LoginForm(Form):
name=simple.StringField(
label='用户名',
validators=[
validators.DataRequired(message='用户名不能为空'),
validators.Length(min=5,max=15,message='用户名的长度必须大于5且小于15')
],
widget=widgets.TextInput(),
render_kw={'class':'form-control'}
)
pwd=simple.PasswordField(
label='密码',
validators=[
validators.DataRequired(message='密码不能为空'),
validators.Length(min=6,max=15,message='密码的长度必须大于6且小于15')
],
widget=widgets.TextInput(),
render_kw={'class':'form-control'}
)
@app.route('/login',methods=['GET','POST'])
def login():
#程序刚进来是get请求，对
if request.method=='GET':
#程序刚进来是get请求先实例化form=LoginForm(),先执行type的__call__方法（有__call__就执行，没有就跳过不执行，它的内部执行了接下来执行LoginForm
的__new__方法，再走LoginForm de __init__方法）
#页面标签数据初始化：data=字典,obj=对象.字段，formdata有getlist方法
form=LoginForm()
return render_template('login.html',form=form)
else:
form=LoginForm(formdata=request.form)
if form.validate():
print('用户提交的数据通过格式验证，提交的值为：',form.data)
else:
print(form.errors)
return render_template('login.html',form=form)
if __name__ == '__main__':
app.run()
“先执行__call__方法”
def __call__(cls, *args, **kwargs):
"""
Construct a new `Form` instance.
Creates the `_unbound_fields` list and the internal `_wtforms_meta`
subclass of the class Meta in order to allow a proper inheritance
hierarchy.
"""
if cls._unbound_fields is None:
fields = []
for name in dir(cls): #（cls是LoginForm这个类，dir把这个类的所有字段都拿到）
if not name.startswith('_'): #（判断如果以'_'开头）
#获取静态字段的值：Unbound_Field对象
unbound_field = getattr(cls, name) #（拿到Unbound_Field的对象）
if hasattr(unbound_field, '_formfield'):
fields.append((name, unbound_field))#(fields这个列表里面是一个元组，元组里面一个是它的名称，一个是它的Unbound_field对象,每个
Unbound_field对象有creation_counter用来计数)
# We keep the name as the second element of the sort
# to ensure a stable sort.
fields.sort(key=lambda x: (x[1].creation_counter, x[0])) #优先按照Unbound_field的count数来排序 ，fieldsshi 排序过后的字段
cls._unbound_fields = fields
# Create a subclass of the 'class Meta' using all the ancestors.
if cls._wtforms_meta is None: bases = []
for mro_class in cls.__mro__: #找到所有的继承关系，相当于继承所有的类
if 'Meta' in mro_class.__dict__: #mro_class.dict__ 就是；类中的所有成员
bases.append(mro_class.Meta)
cls._wtforms_meta = type('Meta', tuple(bases), {}) #type('Meta')表示。自己创建一个Meta类继承bases
return type.__call__(cls, *args, **kwargs)
'执行login的__new__方法，没有__new__方法执行它的__init__方法'
def __init__(self, formdata=None, obj=None, prefix='', data=None, meta=None, **kwargs):
meta_obj = self._wtforms_meta() #原来创建的Meta类（实例化meta）
if meta is not None and isinstance(meta, dict):
meta_obj.update_values(meta)
super(Form, self).__init__(self._unbound_fields, meta=meta_obj, prefix=prefix)
for name, field in iteritems(self._fields):
# Set all the fields to attributes so that they obscure the class
# attributes with the same names.
setattr(self, name, field)
self.process(formdata, obj, data=data, **kwargs)
class BaseForm(object):
"""
Base Form Class. Provides core behaviour like field construction,
validation, and data and error proxying.
"""
def __init__(self, fields, prefix='', meta=DefaultMeta()):
"""
:param fields:
A dict or sequence of 2-tuples of partially-constructed fields.
:param prefix:
If provided, all fields will have their name prefixed with the
value.
:param meta:
A meta instance which is used for configuration and customization
of WTForms behaviors.
"""
if prefix and prefix[-1] not in '-_;:/.':
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:
self._csrf = meta.build_csrf(self)
extra_fields.extend(self._csrf.setup_form(self))
for name, unbound_field in itertools.chain(fields, extra_fields):
options = dict(name=name, prefix=prefix, translations=translations)
#对每一个UNbound中的字段进行实例化
field = meta.bind_field(self, unbound_field, options)
self._fields[name] = field
get执行完现在开始校验
def validate(self):
"""
Validates the form by calling `validate` on each field, passing any
extra `Form.validate_<fieldname>` validators to the field validator.
"""
extra = {}
for name in self._fields: #_fields是所有的字段
inline = getattr(self.__class__, 'validate_%s' % name, None)
if inline is not None:
extra[name] = [inline]
return super(Form, self).validate(extra) #调用父类的validate
你觉得基础知识那些最重要函数也重要， 装饰器，闭包也是蛮重要的。mainxiang面向对象基础流程也是挺重要的，为什么，因为它的流程我知道是
通过流程type，__call__,__new__再到这个方法，原来不知道，后来通过看了看源码就了解了。
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