None error when comparing words using the lenght of themselves

Question

I am trying to place a restriction on the minimum number of characters that a subject can use in a form field using Otree. I want that if the subjects put a name that is less than 4 characters long, the application shows them an error that says they must write a longer word.

I am using len but I am getting the following error:

'NoneType' has no len()

Can someone help me figure out what is wrong in the code and help me fix it?

This is my pages.py code.


class Consentimiento(Page):

    form_model = 'player'
    form_fields = ['consentimiento', 'consentimienton',]

    def consentimiento_error_message(self, value):
        print('El nombre es', value)
        if len(self.player.consentimiento)) < Constants.number:
            return 'Por favor en el campo de nombre debe poner mínimo 4 letras'

This is my models.py code

consentimienton =  models.StringField( max_length=50 )

what is this? self.player.consentimiento Also, consentimiento and consentimienton are easy to mix — Daemon Painter, Nov 16 '20 at 14:21
self.player.consentimiento is a empty stringField where the people put their names. — Diego Montaña, Nov 16 '20 at 14:38
Are you sure it is of type stringField? Try to print out the type of `self.player.consentimiento`, then check if it is a compatible type of `len()` — Daemon Painter, Nov 16 '20 at 14:40

score 0 · Answer 1 · answered Nov 20 '20 at 10:41

I noticed several errors in your working example.

len(self.player.consentimiento) is checking the data, not the input provided by the user. You should replace it with len(value). (Also mind the extra paranthesis)
You are using fieldname_error_message(self,value) function. This should be defined:
- for the field, not for the page.
- in models.py under your model, not in pages.py.

So in the end you should have the following in models.py:

# Don't forget to define number field in Constants

class Player(BasePlayer):
    consentimienton =  models.StringField( max_length=50 )

    def consentimienton_error_message(self, value):
        print('El nombre es', value)
        if len(value) < Constants.number:
            return 'Por favor en el campo de nombre debe poner mínimo 4 letras'

and this in your pages.py:

class Consentimiento(Page):
    form_model = 'player'
    form_fields = ['consentimienton']

None error when comparing words using the lenght of themselves

1 Answers1