French local : Use class Validators for SIRET and SIREN model fields, do not format output

[LLyaudet]

Hello,

Right now the SIRET and SIREN model fields use SIRET and SIREN form fields that do the validation.
I prefer the architecture of the IBAN and BIC fields in generic that use class Validators,
since you can call the validators without using form fields.
Would you accept if I submit a PR with a new file validators.py in fr/
and add in it SIRENValidator and SIRETValidator classes ?
I would use them as is done for IBANValidator and BICValidator.

There is also an annoying thing :
SIRET is max length 14
but it is formatted with spaces.
Thus if in Django admin you modify a form with a valid SIRET in it you get this error :
"Ensure this value has at most 14 characters (it has 17)."

I don't know what is the nicest way to avoid this :

• remove formatting in

  django-localflavor/localflavor/fr/forms.py

  Lines 251 to 255 in 80c6584

  	def prepare_value(self, value):
  	if value is None:
  	return value
  	value = value.replace(' ', '').replace('-', '')
  	return ' '.join((value[:3], value[3:6], value[6:9], value[9:]))

  ?
• change maxlength from 14 to 17 ?
  Modifying a SIRET each time you submit a form because of this is an unvolontary "dark pattern" ;)

Thanks, best regards,
Laurent Lyaudet

[LLyaudet]

For the annoying formatting, I have found a workaround :
https://stackoverflow.com/questions/61896109/changing-max-length-on-a-charfield-for-a-modelform

class MyModelForm(forms.ModelForm):
    siret = FRSIRETField(max_length=17)

[LLyaudet]

If you want to keep some arguments from the model, the workaround is more complicated (and ugly) :

class MyModelForm(forms.ModelForm):
    # siret = FRSIRETField(max_length=17) will not work with blank=True

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields["siret"].max_length = 17
        for i, validator in enumerate(self.fields["siret"].validators):
            if isinstance(validator, MaxLengthValidator):
                self.fields["siret"].validators[i] = MaxLengthValidator(17)
                break
        self.fields["siret"].widget.attrs["maxlength"] = 17