Perl ABC

The value of can be expressed in the format & lt; value & gt; . You can also use it to create new values such as %Perl .

It maps to the following parameters:

{
  title =>'%Perl',
  price => 1000,
  a =>'%Ken%'
}

Keys not specified in the map method will not be mapped. The key b is not mapped in this example.

If you want to change the value a little more flexibly, you can use the subroutine reference. Since the original value can be obtained with the first argument, the new value is returned.

Original key name => [new key name => sub {return'%'. $_[0].'%'}]

Parameter mapping conditions

The default mapping conditions are as follows:

The value is defined and has a length

So the following parameters are mapped.

title =>'Perl',

However, anything that does not have an empty string, undefined value, or the key itself is not mapped. This is because the mapping is intended for web applications.

title =>'',
title => undef

Use the condition attribute to change this condition. You can set the reference of any subroutine or the strings "length", "defined", and "exists" as special values.

$mapper->condition('length'); # Same as default
$mapper->condition('defined'); # value is defined
$mapper->condition('exists'); # key exists
$mapper->condition(sub {defined $_[0]}); # Reference to any subroutine

It is also possible to set each key individually as follows with the map method.

$mapper->map(
  Old key => [new key => new value, {condtion =>'defined'}],
);