How do I validate wtforms fields against one another?

Question

I have three identical SelectField inputs in a form, each with the same set of options. I can't use one multiple select.

I want to make sure that the user selects three different choices for these three fields.

In custom validation, it appears that you can only reference one field at a time, not compare the value of this field to others. How can I do that? Thanks!

Answer 1

You can override validate in your Form...

class MyForm(Form):     select1 = SelectField('Select 1', ...)     select2 = SelectField('Select 2', ...)     select3 = SelectField('Select 3', ...)     def validate(self):         if not Form.validate(self):             return False         result = True         seen = set()         for field in [self.select1, self.select2, self.select3]:             if field.data in seen:                 field.errors.append('Please select three distinct choices.')                 result = False             else:                 seen.add(field.data)         return result