The "None" placeholder is for a custom error message. I always look to the
source code when I have questions like this (which is a frequent occurrence
for me). Here is a sample from the source:
class IS_EQUAL_TO(Validator):
"""
example::
INPUT(_type='text', _name='password')
INPUT(_type='text', _name='password2',
requires=IS_EQUAL_TO(request.vars.password))
the argument of IS_EQUAL_TO is a string
>>> IS_EQUAL_TO('aaa')('aaa')
('aaa', None)
>>> IS_EQUAL_TO('aaa')('aab')
('aab', 'no match')
"""
def __init__(self, expression, error_message='No match'):
self.expression = expression
self.error_message = error_message
def __call__(self, value):
if value == self.expression:
return (value, None)
return (value, translate(self.error_message))
As you can see, a custom error message is initialized during the init()
phase and passed back if there is an error during the call() phase.
-- Joe
On Friday, April 18, 2014 10:24:24 AM UTC-7, [email protected] wrote:
>
> This is a very important question that i would like to complement.
>
> You can use a single custom validator for any kind of parse you want to
> perform on any particular field, like this.
>
> class process_field():
> def __init__(self, func):
> self.func = func
> def __call__(self, value):
> return (self.func(value), None)
>
> db.define_table("people",
> Field("name", "string", length=50,
> requires=process_field(str.capitalize))
> )
>
> This passes a function to the validator (proccess_field) and outputs the
> result of the inserted value. This way you dont need to create many
> validators for each field.
>
> I dont know what None is supposed to be, does anyone knows about it?
>
> Thanks.
>
>
--
Resources:
- http://web2py.com
- http://web2py.com/book (Documentation)
- http://github.com/web2py/web2py (Source code)
- https://code.google.com/p/web2py/issues/list (Report Issues)
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