rollerverbrauch/app/rollerverbrauch/forms.py

from flask_wtf import Form
from wtforms import DateField, IntegerField, DecimalField, StringField, SelectField, SubmitField
from wtforms.validators import ValidationError, Length


def date_check(form, field):
    if field.data < form.pitstop.date:
        raise ValidationError('The new date must after %s' % form.pitstop.date)


def odometer_check(form, field):
    if field.data <= form.pitstop.odometer:
        raise ValidationError('The new odometer value must be higher than %i km' % form.pitstop.odometer)


def litres_check(form, field):
    if field.data is not None and field.data <= 0:
        raise ValidationError('You must fuel at least 0.1 l')


class SelectVehicleForm(Form):
    vehicle = SelectField('Vehicle', coerce=int)
    submit = SubmitField(label='Do it!')


class CreatePitstopForm(Form):
    date = DateField('Date of Pitstop', validators=[date_check])
    odometer = IntegerField('Odometer (km)', validators=[odometer_check])
    litres = DecimalField('Litres (l)', places=2, validators=[litres_check])
    submit = SubmitField(label='Do it!')
    pitstop = None

    def set_pitstop(self, pitstop):
        self.pitstop = pitstop


class EditVehicleForm(Form):
    name = StringField('Name', validators=[Length(1, 255)])
    submit = SubmitField(label='Do it!')


class DeleteVehicleForm(Form):
    submit = SubmitField(label='Do it!')