perl hash with array - arrays

Question

I did same hash like this:
my %tags_hash;
Then I iterate some map and add value into #tags_hash:
if (#tagslist) {
for (my $i = 0; $i <= $#tagslist; $i++) {
my %tag = %{$tagslist[$i]};
$tags_hash{$tag{'refid'}} = $tag{'name'};
}}
But I would like to have has with array, so when key exists then add value to array.
Something like this:
e.g. of iterations
1,
key = 1
value = "good"
{1:['good']}
2,
key = 1
value = "bad"
{1:['good', 'bad']}
3,
key = 2
value = "bad"
{1:['good', 'bad'], 2:['bad']}
And then I want to get array from the key:
print $tags_hash{'1'};
Returns: ['good', 'bad']

Answer 1

An extended example:
#!/usr/bin/perl
use strict;
use warnings;
my $hash = {}; # hash ref
#populate hash
push #{ $hash->{1} }, 'good';
push #{ $hash->{1} }, 'bad';
push #{ $hash->{2} }, 'bad';
my #keys = keys %{ $hash }; # get hash keys
foreach my $key (#keys) { # crawl through hash
print "$key: ";
my #list = #{$hash->{$key}}; # get list associate within this key
foreach my $item (#list) { # iterate through items
print "$item ";
}
print "\n";
}
output:
1: good bad
2: bad

Answer 2

So the value of the hash element to be an array ref. Once you have that, all you need to do is push the value onto the array.
$hash{$key} //= [];
push #{ $hash{$key} }, $val;
Or the following:
push #{ $hash{$key} //= [] }, $val;
Or, thanks to autovivification, just the following:
push #{ $hash{$key} }, $val;
For example,
for (
[ 1, 'good' ],
[ 1, 'bad' ],
[ 2, 'bad' ],
) {
my ($key, $val) = #$_;
push #{ $hash{$key} }, $val;
}