WTForms crea un número variable de campos

Question

¿Cómo crearía dinámicamente unos pocos campos de formulario con diferentes preguntas, pero las mismas respuestas?

from wtforms import Form, RadioField 
from wtforms.validators import Required 

class VariableForm(Form): 

    def __init__(formdata=None, obj=None, prefix='', **kwargs): 
     super(VariableForm, self).__init__(formdata, obj, prefix, **kwargs) 
     questions = kwargs['questions'] 
     // How to to dynamically create three questions formatted as below? 

    question = RadioField(
      # question ?, 
      [Required()], 
      choices = [('yes', 'Yes'), ('no', 'No')], 
      ) 

questions = ("Do you like peas?", "Do you like tea?", "Are you nice?") 
form = VariableForm(questions = questions) 

Answer 1

Fue in the docs todo el tiempo.

def my_view(): 
    class F(MyBaseForm): 
     pass 

    F.username = TextField('username') 
    for name in iterate_some_model_dynamically(): 
     setattr(F, name, TextField(name.title())) 

    form = F(request.POST, ...) 
    # do view stuff 

Lo que no se dan cuenta es que los atributos de clase deben establecerse antes de se produce ninguna ejemplificación. La claridad viene de este bitbucket comment:

This is not a bug, it is by design. There are a lot of problems with adding fields to instantiated forms - For example, data comes in through the Form constructor.

If you reread the thread you link, you'll notice you need to derive the class, add fields to that, and then instantiate the new class. Typically you'll do this inside your view handler.

Answer 2

Ya casi ha terminado:

CHOICES = [('yes', 'Yes'), ('no', 'No')] 

class VariableForm(Form): 

    def __new__(cls, questions, **kwargs): 
     for index, question in enumerate(questions): 
      field_name = "question_{}".format(index) 
      field = RadioField(question, 
            validators=[Required()], 
            choices=CHOICES) 
      setattr(cls, field_name, field) 
     return super(VariableForm, cls).__new__(cls, **kwargs)