Wrapper to allow any spawner to be launch with an option form.

formspawner.py

from wtforms import Form
from jinja2 import Template
from collections import Sequence
from traitlets import Type, HasTraits

class MetaSpawnerForm(Form):
    form_template = Template("""
   {% for field in form %}
       {{ field.label() }}
       {{ field() }}
       <br>
   {% endfor %}""")

    class MockMultiDict(dict):
        def getlist(self, key):
            value = self[key]
            return value if isinstance(value, list) else [self[key]]

    @property
    def options_form(self):
       return self.form_template.render(form=self)

    def options_from_form(self, options):
        self.process(formdata=self.MockMultiDict(options))
        if not self.validate():
            raise Exception(self.errors)
        return self.data

class FormSpawner(HasTraits):
    form_type = Type(MetaSpawnerForm, allow_none=False, help="")
    def __init__(self, *args, **kargs):
        super().__init__(*args, **kargs)
        self.form = self.form_type()
        self.options_form = self.form.options_form
        self.options_from_form = self.form.options_from_form

def generate_form_spawner(baseclass, **kargs):
    form_type = type("SpawnerForm", (MetaSpawnerForm,), kargs)
    return type(baseclass.__name__ + "_form", (baseclass, FormSpawner), {'form_type': form_type})