Python 检查Flask应用程序中的数据库中是否存在所有三个WTForm

我如何编写一个验证函数来检查上面的db查询，如果所有三个数据都存在于db中，那么应该向用户抛出一个错误。

---

不确定如何进行验证，因为

def validate\u days（self，days）：

只能检查该值是否存在于db中这几乎是正确的，但您需要参考

self

上的值并返回真/假

class TimeSheet(FlaskForm):
    days = SelectField('Please Select a Date', choices=[('1', '1'),
                                                        ('2', '2'),
                                                        ('3', '3'),
                                                        ('4', '4'),
                                                        ('5', '5'),
                                                        ('6', '6'),
                                                        ('7', '7'),
                                                        ('8', '8'),
                                                        ('9', '9'),
                                                        ('10', '10'),
                                                        ('11', '11'),
                                                        ('12', '12'),
                                                        ('13', '13'),
                                                        ('14', '14'),
                                                        ('15', '15'),
                                                        ('16', '16'),
                                                        ('17', '17'),
                                                        ('18', '18'),
                                                        ('19', '19'),
                                                        ('20', '20'),
                                                        ('21', '21'),
                                                        ('22', '22'),
                                                        ('23', '23'),
                                                        ('24', '24'),
                                                        ('25', '25'),
                                                        ('26', '26'),
                                                        ('27', '27'),
                                                        ('28', '28'),
                                                        ('29', '29'),
                                                        ('30', '30'),
                                                        ('31', '31')])
    months = SelectField('Please Select a Month', choices=[('1', '1'),
                                                           ('2', '2'),
                                                           ('3', '3'),
                                                           ('4', '4'),
                                                           ('5', '5'),
                                                           ('6', '6'),
                                                           ('7', '7'),
                                                           ('8', '8'),
                                                           ('9', '9'),
                                                           ('10', '10'),
                                                           ('11', '11'),
                                                           ('12', '12')])
    year = SelectField('Please Select a Year', choices=[('2018', '2018'),
                                                        ('2019', '2019'),
                                                        ('2020', '2020'),
                                                        ('2021', '2021'),
                                                        ('2022', '2022')])
    submit = SubmitField('Submit')

    def validate(self, days,months,year):
        d = Timesheet.query.filter_by(
            user_id=current_user.id, days=days.data,months=months.data,years=year.data).all()
        if d:
            raise ValidationError(
                'Date has already been selected')

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为什么要投否决票？至少请给我链接，如果它已经回答

def validate(self):
    rv = FlaskForm.validate(self)
    if not rv:
        return False

    d = Timesheet.query.filter_by(user_id=current_user.id,
                                  days=self.days.data, 
                                  months=self.months.data,
                                  years=self.year.data).all()
    if d:
        self.days.errors.append('Date has already been selected')
        return False

    return True