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-zd$@$!%*?&]{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()


<!--<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">

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】