Flask-WTForms How to bypass automatic pre-validate for Radio Fields

Question

I'm trying to create a form with two Submit Fields - Filter and Submit. For Filter, I have a Select Field with a list of names, and if they select a name I want to filter the existing page based on that name. For Submit, I have a Radio Field and want to jump to a different page based on the selection. For Filter, I don't want any validation of the Radio Field, and for Submit I don't want any validation of the Select Field.

This appears to work fine with my Select Field - it only validates when I hit the Filter button. But for the Radio Field, it always validates and I get the following regardless of which button I click:

[Not a valid choice]

Here are my code snippets. Html:

        <h2>Filter</h2>
        <p>
            {{ form.player.label }}<br>
            {{ form.player }}
            {% for error in form.player.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.filter() }}</p>
        <h2>Games to be played</h2>
        <p>
            {{ form.result.label }}<br>
            {{ form.result }}
            {% for error in form.result.errors %}
            <span style="color: red;">[{{ error }}]</span>
            {% endfor %}
        </p>
        <p>{{ form.submit() }}</p>

Form:

class MatchupsForm(FlaskForm):
    player = SelectField(u'Filter by Player', coerce=int)
    filter = SubmitField('Filter')
    result = RadioField(u'Select Game to Update', coerce=int)
    submit = SubmitField('Update')

    def validate_player(self, player):
        if (player.data == 0) and self.filter.data:
            raise ValidationError("Please select a Name to filter on")
            return False
        return True
    def validate_result(self, result):
        if not result.data and self.submit.data:
            raise ValidationError("Please select a Matchup")
            return False
        return True

I've tried the suggestion from Flask-WTForms How to override pre validate on Radio Fields by creating

    def pre_validate(self, form):
        for v, _ in self.choices:
            if self.data == v:
                break
        else:
            raise ValueError(self.gettext('Need a Matchup'))

But that didn't work either - I get the same error. Note that my additional validators seem to work correctly - when I click Filter with no player selection, I see that error, but if I click Submit with no result selection, I see both the default error and my customized one.

[Not a valid choice] [Please select a Matchup]

Appreciate any insights on how to make this work.

Answer 1

Try to manually create an hidden field with the same name as your RadioField and give it a value you can manually validate when the form submit.