简介
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 wtforms
用户登录注册示例
1. 用户登录
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）；
############################## app.py #############################
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask, render_template, request, redirect
from wtforms import Form
from wtforms.fields import core # 字段大部分都在core html5 simple 中
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', # 显示名称
validators=[ # 校验
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(), # 插件
render_kw={'class': 'form-control'} # 渲染
)
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() # 实例化
return render_template('login.html', form=form)
else:
form = LoginForm(formdata=request.form) # 校验
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()
############################## login.html #############################
<!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>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。
############################## app.py #############################
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 # 会自动转化为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): # 钩子函数，filed 代表要检验的字段，self 代表所有的数据
"""
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，验证的是本字段
raise validators.StopValidation("密码不一致") # 不再继续后续验证，验证的是本字段
@app.route('/register', methods=['GET', 'POST'])
def register():
if request.method == 'GET':
form = RegisterForm(data={'gender': 1}) # data 为form 传值
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()
############################## login.html #############################
<!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. meta
使用WTFrom 提供的 csrf_token，一般不怎么用
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask, render_template, request, redirect, session
from wtforms import Form
from wtforms.csrf.core import CSRF
from wtforms.fields import core
from wtforms.fields import html5
from wtforms.fields import simple
from wtforms import validators
from wtforms import widgets
from hashlib import md5
app = Flask(__name__, template_folder='templates')
app.debug = True
class MyCSRF(CSRF): # 继承CSRF，实现自己的规则
"""
Generate a CSRF token based on the user's IP. I am probably not very
secure, so don't use me.
"""
def setup_form(self, form):
self.csrf_context = form.meta.csrf_context()
self.csrf_secret = form.meta.csrf_secret
return super(MyCSRF, self).setup_form(form)
def generate_csrf_token(self, csrf_token):
gid = self.csrf_secret + self.csrf_context
token = md5(gid.encode('utf-8')).hexdigest()
return token
def validate_csrf_token(self, form, field):
print(field.data, field.current_token)
if field.data != field.current_token:
raise ValueError('Invalid CSRF')
class TestForm(Form):
name = html5.EmailField(label='用户名')
pwd = simple.StringField(label='密码')
class Meta:
# -- CSRF
# 是否自动生成CSRF标签
csrf = True
# 生成CSRF标签name
csrf_field_name = 'csrf_token'
# 自动生成标签的值，加密用的csrf_secret
csrf_secret = 'xxxxxx'
# 自动生成标签的值，加密用的csrf_context
csrf_context = lambda x: request.url
# 生成和比较csrf标签
csrf_class = MyCSRF
# -- i18n
# 是否支持本地化
# locales = False
locales = ('zh', 'en')
# 是否对本地化进行缓存
cache_translations = True
# 保存本地化缓存信息的字段
translations_cache = {}
@app.route('/index/', methods=['GET', 'POST'])
def index():
if request.method == 'GET':
form = TestForm()
else:
form = TestForm(formdata=request.form)
if form.validate():
print(form)
return render_template('index.html', form=form)
if __name__ == '__main__':
app.run()其他：
1. metaclass
第一阶段
class MyType(type):
def __init__(self, *args, **kwargs):
print('MyType创建类',self)
super(MyType, self).__init__(*args, **kwargs)
def __call__(self, *args, **kwargs):
obj = super(MyType, self).__call__(*args, **kwargs)
print('类创建对象', self, obj)
return obj
class Foo(object,metaclass=MyType):
user = 'flepeng'
age = 18
obj = Foo()第二阶段
class MyType(type):
def __init__(self, *args, **kwargs):
super(MyType, self).__init__(*args, **kwargs)
def __call__(cls, *args, **kwargs):
v = dir(cls)
obj = super(MyType, cls).__call__(*args, **kwargs)
return obj
class Foo(MyType('MyType', (object,), {})):
user = 'wupeiqi'
age = 18
obj = Foo()第三阶段
class MyType(type):
def __init__(self, *args, **kwargs):
super(MyType, self).__init__(*args, **kwargs)
def __call__(cls, *args, **kwargs):
v = dir(cls)
obj = super(MyType, cls).__call__(*args, **kwargs)
return obj
def with_metaclass(arg,base):
return MyType('MyType', (base,), {})
class Foo(with_metaclass(MyType,object)):
user = 'wupeiqi'
age = 18
obj = Foo()2. 实例化流程分析
# 源码流程
1. 执行type的 __call__ 方法，读取字段到静态字段 cls._unbound_fields 中； meta类读取到cls._wtforms_meta中
2. 执行构造方法
a. 循环cls._unbound_fields中的字段，并执行字段的bind方法，然后将返回值添加到 self._fields[name] 中。
即：
_fields = {
name: wtforms.fields.core.StringField(),
}
PS：由于字段中的__new__方法，实例化时：name = simple.StringField(label='用户名')，创建的是UnboundField(cls, *args, **kwargs)，当执行完bind之后，才变成执行 wtforms.fields.core.StringField()
b. 循环_fields，为对象设置属性
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)
c. 执行process，为字段设置默认值：self.process(formdata, obj, data=data, **kwargs)
优先级：obj,data,formdata;
再循环执行每个字段的process方法，为每个字段设置值：
for name, field, in iteritems(self._fields):
if obj is not None and hasattr(obj, name):
field.process(formdata, getattr(obj, name))
elif name in kwargs:
field.process(formdata, kwargs[name])
else:
field.process(formdata)
执行每个字段的process方法，为字段的data和字段的raw_data赋值
def process(self, formdata, data=unset_value):
self.process_errors = []
if data is unset_value:
try:
data = self.default()
except TypeError:
data = self.default
self.object_data = data
try:
self.process_data(data)
except ValueError as e:
self.process_errors.append(e.args[0])
if formdata:
try:
if self.name in formdata:
self.raw_data = formdata.getlist(self.name)
else:
self.raw_data = []
self.process_formdata(self.raw_data)
except ValueError as e:
self.process_errors.append(e.args[0])
try:
for filter in self.filters:
self.data = filter(self.data)
except ValueError as e:
self.process_errors.append(e.args[0])
d. 页面上执行print(form.name) 时，打印标签
因为执行了：
字段的 __str__ 方法
字符的 __call__ 方法
self.meta.render_field(self, kwargs)
def render_field(self, field, render_kw):
other_kw = getattr(field, 'render_kw', None)
if other_kw is not None:
render_kw = dict(other_kw, **render_kw)
return field.widget(field, **render_kw)
执行字段的插件对象的 __call__ 方法，返回标签字符串3. 验证流程分析
a. 执行form的validate方法，获取钩子方法
def validate(self):
extra = {}
for name in self._fields:
inline = getattr(self.__class__, 'validate_%s' % name, None)
if inline is not None:
extra[name] = [inline]
return super(Form, self).validate(extra)
b. 循环每一个字段，执行字段的 validate 方法进行校验(参数传递了钩子函数)
def validate(self, extra_validators=None):
self._errors = None
success = True
for name, field in iteritems(self._fields):
if extra_validators is not None and name in extra_validators:
extra = extra_validators[name]
else:
extra = tuple()
if not field.validate(self, extra):
success = False
return success
c. 每个字段进行验证时候
字段的pre_validate 【预留的扩展】
字段的_run_validation_chain，对正则和字段的钩子函数进行校验
字段的post_validate【预留的扩展】
################################## class FormMeta ###############################
class FormMeta(type):
# 创建类时，调用的方法
def __init__(cls, name, bases, attrs):
type.__init__(cls, name, bases, attrs)
cls._unbound_fields = None
cls._wtforms_meta = None
# 实例化类时调用的方法
def __call__(cls, *args, **kwargs):
if cls._unbound_fields is None:
fields = []
for name in dir(cls):
if not name.startswith('_'):
unbound_field = getattr(cls, name)
if hasattr(unbound_field, '_formfield'): # 只要是继承自File，_formfield = True
fields.append((name, unbound_field)) # 将字段添加至fields
fields.sort(key=lambda x: (x[1].creation_counter, x[0]))
cls._unbound_fields = fields # _unbound_fields =[字段对应的示例,]
if cls._wtforms_meta is None:
bases = []
for mro_class in cls.__mro__:
if 'Meta' in mro_class.__dict__:
bases.append(mro_class.Meta) # 将所有的Meta添加至bases中
cls._wtforms_meta = type('Meta', tuple(bases), {}) # 创建一个新的Meta，并继承自找到的Meta列表
return type.__call__(cls, *args, **kwargs) # 执行type的call方法，前面的都是派生的
################################## class Form ###############################
# class Form(BaseForm , classmate=FormMeta)
class Form(with_metaclass(FormMeta, BaseForm)):
Meta = DefaultMeta
def __init__(self, formdata=None, obj=None, prefix='', data=None, meta=None, **kwargs):
meta_obj = self._wtforms_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):
setattr(self, name, field)
self.process(formdata, obj, data=data, **kwargs)
def __setitem__(self, name, value):
raise TypeError('Fields may not be added to Form instances, only classes.')
def __delitem__(self, name):
del self._fields[name]
setattr(self, name, None)
def __delattr__(self, name):
if name in self._fields:
self.__delitem__(name)
else:
unbound_field = getattr(self.__class__, name, None)
if unbound_field is not None and hasattr(unbound_field, '_formfield'):
setattr(self, name, None)
else:
super(Form, self).__delattr__(name)
def validate(self):
extra = {}
for name in self._fields:
inline = getattr(self.__class__, 'validate_%s' % name, None)
if inline is not None:
extra[name] = [inline]
return super(Form, self).validate(extra)
################################## class BaseForm ###############################
class BaseForm(object):
def __init__(self, fields, prefix='', meta=DefaultMeta()):
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)
field = meta.bind_field(self, unbound_field, options)
self._fields[name] = field