CODEWITHSUNDEEP
validationflaskradio-buttonflask-wtformswtforms
machump
machump

Reputation: 1267

WTForms custom validator- RequiredIf on a RadioField

I borrowed a validator that requires the user to input data if the value of another field is a certain value:

class RequiredIf(object):
    def __init__(self, *args, **kwargs):
            self.conditions = kwargs
    def __call__(self, form, field):
            for name, data in self.conditions.items():
                if name not in form._fields:
                    Optional(form, field)
                else:
                    condition_field = form._fields.get(name)
                if condition_field.data == data and not field.data:
                    DataRequired()(form, field)
                    Optional()(form, field)

This works really well when the field containing the validator argument is a TextField, but it doesn't seem to work when the field is a RadioField. How can I adapt the validator so that this also works on RadioFields?

As it stands, regardless of whether the validation condition applies or not, not a valid choice is always returned for the RadioField.

Thanks in advance.

For example:

class new_form(Form):
    code=BooleanField('Do you code?')
    code2=RadioField('If so, what languages do you use?',
        choices=[('python','python'),('C++','C++')],
        validators=[RequiredIf(code=1)])

Regardless of whether the BooleanField code is checked or not, this is not a valid choice is always returned for code2. I would like a validator that requires an input for any type of field(including RadioField), conditional on the value of another field (code=1 in this case).

Upvotes: 2

Views: 1531

Answers (1)

Danila Ganchar
Danila Ganchar

Reputation: 11232

Updated!. You can create any custom processing using __call__. Example:

from multidict import CIMultiDict
from wtforms import Form, RadioField, BooleanField


class RequiredIf(object):

    def __init__(self, **kwargs):
        self.conditions = kwargs

    def __call__(self, form, field):
        # NOTE! you can create here any custom processing
        current_value = form.data.get(field.name)
        if current_value == 'None':
            for condition_field, reserved_value in self.conditions.items():
                dependent_value = form.data.get(condition_field)
                if condition_field not in form.data:
                    continue
                elif dependent_value == reserved_value:
                    # just an example of error
                    raise Exception(
                        'Invalid value of field "%s". Field is required when %s==%s' % (
                            field.name,
                            condition_field,
                            dependent_value
                        ))

class NewForm(Form):
    code = BooleanField('Do you code?')
    code2 = RadioField(
        'If so, what languages do you use?',
        choices=[('python', 'python'), ('C++', 'C++')],
        validators=[RequiredIf(code=True)])

form = NewForm(formdata=CIMultiDict(code=True, code2='python'), )
form.validate()  # valid data - without errors

# invalid data
form = NewForm(formdata=CIMultiDict(code=True), )
form.validate()  # invalid data - Exception: Invalid value of field "code2". Field is required when code==True

One more example with 2 RadioField:

class NewForm(Form):
    list_one = RadioField('City/Country', choices=['city', 'country'])
    list_two = RadioField(
        'Cities',
        choices=[('minsk', 'Minsk'), ('tbilisi', 'Tbilisi')],
        validators=[RequiredIf(list_one='city')])


form = NewForm(formdata=CIMultiDict(list_one='city', list_two='minsk'), )
form.validate()  # without errors
form = NewForm(formdata=CIMultiDict(list_one='country'), )
form.validate()  # without errors
form = NewForm(formdata=CIMultiDict(list_one='city'), )
form.validate()  # invalid data - Exception: Invalid value of field "list_two". Field is required when list_one==city

Hope this helps.

Upvotes: 3

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