WTForms組件

WTForms組件

WTForms是一個支持多個web框架的form組件，主要用於對用戶請求數據進行驗證。

注意:

from wtforms import Form

    和

    from flask_wtf  import FlaskForm  須要設置csfr

安裝

pip3 install wtforms

如何使用

1 登陸實例：

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
    

   # 自定義 驗證

    class MyValidator(object):

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

        def __call__(self, form, field):
            if field.data == 'a':
                return None
            raise ValidationError('驗證失敗')


    class LoginForm(Form):
        name = simple.StringField(
            label='用戶名',
            validators=[
                MyValidator,
                validators.DataRequired(message='用戶名不能爲空.'),
                validators.Length(min=6, max=18, message='用戶名長度必須大於%(min)d且小於%(max)d')
            ],
            widget=widgets.TextInput(),
            render_kw={'class': 'form-control'}
    
        )
        pwd = simple.PasswordField(
            label='密碼',
            validators=[
                validators.DataRequired(message='密碼不能爲空.'),
                validators.Length(min=8, message='用戶名長度必須大於%(min)d'),
                validators.Regexp(regex="^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[$@$!%*?&])[A-Za-z\d$@$!%*?&]{8,}",
                                  message='密碼至少8個字符，至少1個大寫字母，1個小寫字母，1個數字和1個特殊字符')
    
            ],
            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('用戶提交數據經過格式驗證，提交的值爲：', 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 註冊實例：

class RegisterForm(Form):
    name = simple.StringField(
        label='用戶名',
        validators=[
            validators.DataRequired()
        ],
        widget=widgets.TextInput(),
        render_kw={'class': 'form-control'},
        default='alex'
    )
    pwd = simple.PasswordField(
        label='密碼',
        validators=[
            validators.DataRequired(message='密碼不能爲空.')
        ],
        widget=widgets.PasswordInput(),
        render_kw={'class': 'form-control'}
    )
    pwd_confirm = simple.PasswordField(
        label='重複密碼',
        validators=[
            validators.DataRequired(message='重複密碼不能爲空.'),
            validators.EqualTo('pwd', message="兩次密碼輸入不一致")
        ],
        widget=widgets.PasswordInput(),
        render_kw={'class': 'form-control'}
    )

    email = html5.EmailField(
        label='郵箱',
        validators=[
            validators.DataRequired(message='郵箱不能爲空.'),
            validators.Email(message='郵箱格式錯誤')
        ],
        widget=widgets.TextInput(input_type='email'),
        render_kw={'class': 'form-control'}
    )
    gender = core.RadioField(
        label='性別',
        choices=(
            (1, '男'),
            (2, '女'),
        ),
        coerce=int
    )
    city = core.SelectField(
        label='城市',
        choices=(
            ('bj', '北京'),
            ('sh', '上海'),
        )
    )
    hobby = core.SelectMultipleField(
        label='愛好',
        choices=(
            (1, '籃球'),
            (2, '足球'),                       #  也能夠從數據庫動態獲取
    ),
    coerce=int
)

    favor = core.SelectMultipleField(
        label='喜愛',
        choices=(
            (1, '籃球'),
            (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, '籃球'), (2, '足球'), (3, '羽毛球'))           # 動態從數據庫中獲取字段


def validate_pwd_confirm(self, field):
    """
    自定義pwd_confirm字段規則，例：與pwd字段是否一致
    :param field:
    :return:
    """
    # 最開始初始化時，self.data中已經有全部的值

    if field.data != self.data['pwd']:
        # raise validators.ValidationError("密碼不一致") # 繼續後續驗證
        raise validators.StopValidation("密碼不一致")  # 再也不繼續後續驗證


@app.route('/register', methods=['GET', 'POST'])
def register():
    if request.method == 'GET':
        form = RegisterForm(data={'gender': 1})        # 渲染表單時的 設置默認值({'字段':數據})
        return render_template('register.html', form=form)
    else:
        form = RegisterForm(formdata=request.form)
        if form.validate():
            print('用戶提交數據經過格式驗證，提交的值爲：', form.data)
        else:
            print(form.errors)
        return render_template('register.html', form=form)

流程

實例化流程

(

1. 執行type的 __call__ 方法，讀取字段到靜態字段 cls._unbound_fields 中； meta類讀取到cls._wtforms_meta中
2. 執行構造方法
    
    a. 循環cls._unbound_fields中的字段，並執行字段的bind方法，而後將返回值添加到 self._fields[name] 中。
        即：
            _fields = {
                name: wtforms.fields.core.StringField(),
            }
            
        PS：因爲字段中的__new__方法，實例化時：name = simple.StringField(label='用戶名')，建立的是UnboundField(cls, *args, **kwargs)，當執行完bind以後，才變成執行 wtforms.fields.core.StringField()
    
    b. 循環_fields，爲對象設置屬性
        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. 執行process，爲字段設置默認值：self.process(formdata, obj, data=data, **kwargs)
        優先級：obj,data,formdata;
        
        再循環執行每一個字段的process方法，爲每一個字段設置值：
        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)
        
        執行每一個字段的process方法，爲字段的data和字段的raw_data賦值
        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. 頁面上執行print(form.name) 時，打印標籤
        
        由於執行了：
            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)
            執行字段的插件對象的 __call__ 方法，返回標籤字符串

驗證流程

a. 執行form的validate方法，獲取鉤子方法
                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. 循環每個字段，執行字段的 validate 方法進行校驗(參數傳遞了鉤子函數)
        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. 每一個字段進行驗證時候
        字段的pre_validate 【預留的擴展】
        字段的_run_validation_chain，對正則和字段的鉤子函數進行校驗
        字段的post_validate【預留的擴展】