A safer method using Data::Diver: 
use strict;
use Data::Diver 'DiveVal';
use Data::Dump 'dd';

my $root= {
    top => [
        {   first => 1 },
        {   second => {
                key => [
                    0, 1, 2, {
                        three => {
                            exists => 'yes',
                        },
                    },
                ],
            },
        },
    ],
};

DiveVal($root, qw/top 1 second key 3 three exists/) = 'no';
dd($root);

[download]
Output: 
{
  top => [
           { first => 1 },
           { second => { key => [0, 1, 2, { three => { exists => "no" 
+} }] } },
         ],
}

[download]

In reply to Re: Using serialized data structure to change hash key by Arunbear
in thread Using serialized data structure to change hash key by docdurdee

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.