WTForms组件

WTForms组件

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。

注意:

from wtforms import Form

和

from flask_wtf import FlaskForm 需要设置csfr

安装

pip3 install wtforms

如何使用

1 登录实例：

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

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

自定义 验证

class MyValidator(object):

def init(self, message=None):
self.message = message

def call(self, form, field):
if field.data == 'a':
return None
raise ValidationError('验证失败')

class LoginForm(Form):
name = simple.StringField(
label='用户名',
validators=[
MyValidator,
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()

{{form.name.label}} {{form.name}} {{form.name.errors[0] }}

{{form.pwd.label}} {{form.pwd}} {{form.pwd.errors[0] }}

2 注册实例：

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'), # 也可以从数据库动态获取
),
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')) # 动态从数据库中获取字段

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}) # 渲染表单时的 设置默认值({'字段':数据})
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)

流程

实例化流程

(

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

验证流程

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】