Re: RequireIfPresent

[email protected] wrote:
> Dear fellow Formencode Enthusiasts:
> 
> I want to chain a field B to an existing field A, such that if user 
> inputs a value for field A, then field B is required, otherwise if field 
> A is empty, field B is not required.  I looked at RequireIfPresent, and 
> I believe I know how to use it:
> 
>  >>> from formencode import validators
>  >>> ripi_01 = validators.RequireIfPresent('phone_type_pri', 
> present='primary_phone')
>  >>> ripi_01.to_python({'phone_type_pri':'', 'primary_phone':'510 420 
> 4577'})
> 
> Invalid: You must give a value for phone_type_pri
>  >>> ripi_01.to_python({'phone_type_pri':'', 'primary_phone':''})
> {'phone_type_pri': '', 'primary_phone': ''}
>  >>>
> 
> but I can't seem to get it to work in context of my schema.  I get a 
> "Missing value" error message that at first made me conclude my schema 
> was expecting 'phone_type_pri' to be required, and yet when I do input a 
> value for phone_type_pri, e.g., 'home phone', I get the exact same error 
> message as before !  It seems no matter what I do (e.g., if I leave 
> primary_phone empty, if I select a value for phone_type_pri), I will get 
> the following error:
> 
>  phone_type_pri: Missing value
> 
> I searched on Google for RequireIfPresent and "missing value" and saw at 
> least one other user (negus on the Pylons list) with this problem.  
> Please let me know if I am doing something wrong:
> 
> class Appl_Form(formencode.Schema):
>     email = validators.Email(resolve_domain=True, not_empty=True)
>     confirm_email = validators.Email(not_empty=True)
>     primary_phone = validators.PhoneNumber()
>     phone_type_pri = validators.PlainText()
>     chained_validators = [validators.FieldsMatch('email', 
> 'confirm_email'), validators.RequireIfPresent('phone_type_pri', 
> present='primary_phone')]

Schemas require the fields to be present unless you put if_missing=None 
in the validator.  In this case you need:

   phone_type_pri = validators.PlainText(if_missing=None)

I also added an explanation to the RequireIfPresent docstring.

-- 
Ian Bicking : [email protected] : http://blog.ianbicking.org

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