freddo411 has asked for the wisdom of the Perl Monks concerning the following question:

Monks, I am using Data::FormValidator to provide input checking/constraints/filters for my CGI::Application.

Data::FV makes it easy to code constraints on $B and $C, or to require $B and $C if $A exists by setting up rules contained in a hash structure. Like so... 

#  snip

     dependencies   =>
           {  # If A is "N", make list of inputs required
              "A" => {
                   N =>  [ qw/
                          admin_contact_fk                            
+            
                          tech_contact_fk
                          billing_contact_fk
                         / ],
                     }
     },
     constraints => {  # check these inputs with these subs
                 dn_id       => 'OK_int',
                 foo         => 'OK_chars',
     },

#  snip

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I would like to write a construct so that if Input $A = exists, then Input $B and $C have to meet certain constraints. If $A isn't one of the inputs, then the $B anc $C have no constraints

I don't see any way other way, using D::FV, than writing custom constraints that take in $A, $B, and $C to solve my problem. Is this true?

-------------------------------------
Nothing is too wonderful to be true
-- Michael Faraday

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Re: Data::FormValidator question
by freddo411 (Chaplain) on Mar 18, 2004 at 18:56 UTC
    Strangely, I'm replying to myself:

    The answer to my question is yes, one must write a custom constraint. I got this reply from the module author (Mark Stosberg):

    Fred, if using the 'dependencies' system doesn't solve your problem, I think you are right. You could write a custom constraint for b or c, such that they only kick-in if A is present.

    He also suggested that I propose any new functionality to the maintainers list.

    Solving my problem I used the following code (see Data::FormValidator for explaination) 

    
# .. snip
# Part of my hash to pass to D::FV

   constraints => {
      dn_id    => 'OK_int',
      b        => { 
        constraint  => 'custom_constraint_sub_name',
        params      => [ qw/ b a / ],
                  },
      c        => { 
        constraint  => 'custom_constraint_sub_name',
        params      => [ qw/ c a / ],
                  },
   }

# .. snip ...

# Defining my constraint routine elsewhere:

#################################
sub match_custom_constraint_sub_name {
  my $val = shift;
  my $a = shift;
  if ( $a eq 'N' ) {
        return  match_another_custom_constraint($val) ;
  } else {
        return "0";  # use this default value  
}

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    -------------------------------------
    Nothing is too wonderful to be true
    -- Michael Faraday

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