Hey guys! I wanna add a voluntary question for participants, which stores input as float when there is input and "None" when there is not. I try to use field_maybe_none() to achieve my goal but I did not quite understand its usage.

In otree doc, the code is:
# instead of player.abc, do:
abc = player.field_maybe_none('abc')

But I guess it is a way to get the value from an existing variable "player.abc", right? How can I store the data in form fields?

Thanks!

You can make a field optional by adding blank = True when you define your field.
Then you include the field on your HTML page just as you always do, but the field is now optional.

E.g.:
class Player(BasePlayer):
    abc = models.FloatField(blank = True)
    
See the documentation here: https://otree.readthedocs.io/en/latest/forms.html#optional-fields

Thanks a lot, it works!