[dfv] Questions on writing my own contraints

[Jonas B. N. <jo...@gm...>]

Hello,

I am somewhat a heavy user of (out of the box) Data::FormValidator. I  
am currently attempting to port some of my CPAN code, which has  
validation behavior to Data::FormValidator::Constraints::* modules.

I have followed the documentation and everything seems to work, but I  
feel I am missing something, I have examined several of the other  
implementations of constraints on CPAN, but this has not made me  
completely confident in how Data::FormValidator works or at least  
expect me to do things.

So I have a few questions, please bear with me since some of this  
things my be obvious, but I have just not understood the concept  
completely.

I have a constraint module.

It exports by request: valid_cvr, this validates whether a given  
parameter is a valid cvs according to an algorithm implemented in  
Business::DK::CVR.

At the same time I want to support untainting, in that sense that if  
any of the flags:

- untaint_all_constraints
- untaint_constraint_fields

Are set to true, this is also recommended in the POD.

So I have implemented:

match_cvr, also exported by request. The only thing this method does  
is match against the data for a certain format, no actual validation  
is done (see: valid_cvr above).

The implementations I have seen seem to have implemented either valid_  
or match_ as a thin wrapper for the other, so I am unsure as to I need  
to separate the two, which lead to the following questions.

1. If a user defines a profile with a field named cvr, would match_cvr  
be used to untaint this magically and would this not require default  
export? I can see a scenario where the user is only interested in  
untainting data not necessarily validating, so the separation in  
implementation makes sense in my opinion

2. It seems as if a validation, results in auto-untainting, according  
to my tests, where match_cvr is not called at all, so match_cvr does  
not need to be wrapped, is there any policies regarding this I should  
be aware of

So to sort of wrap this way too long mail up, I am unsure as to what  
the role and when a match_ method should be implemented and called.  
Let me know if I am unclear, but I have spent a lot of time writing  
tests to sort of try to get my head around writing my own constraints.


Thanks,

jonasbn
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