Accessing Hash of hash of Array in Perl - perl

Question

I have the following data I wish to access:
$data1=
{'Family' => {
'House' => [
{
'Id' => '1111',
'Name' => 'DFG'
},
{
'Id' => '211',
'Name' => 'ABC'
}
]
}
}
I want to access the each Name field value. I am using this code:
foreach(keys%$data1) {
if(ref($data1->{$_}) eq 'HASH') {
foreach my $inner_key (keys%{$data1->{$_}}) {
print "Key:$inner_key and value:$data1->{$_}->{$inner_key}\n";
}
}
else {
print "Key: $_ and Value: $data1->{$_}\n"
}
}
It prints Key:House and value:ARRAY(OXXX).
I know I am doing something wrong. Since the data in 'House' is an array of hashes, I even tried accessing through $data1->{$_}->{$inner_key}[0]. What is wrong in the code???

Answer 1

You have to dereference array for foreach loop first, and then dereference hashref to reach "Name" values.
print "Key:$inner_key and value:$_->{Name}\n"
for #{$data1->{$_}->{$inner_key}};

Answer 2

You should read perlref first to learn how to create and use references.
Here is a demonstration:
#!/usr/bin/perl
use strict;
use warnings;
my $data1=
{'Family' => {
'House' => [
{
'Id' => '1111',
'Name' => 'DFG'
},
{
'Id' => '211',
'Name' => 'ABC'
}
]
}
};
while (my ($key1, $val1) = each %$data1) {
print "\$key1 = $key1\n";
while (my ($key2, $val2) = each %$val1) {
print "\t\$key2 = $key2\n";
foreach my $val3 (#$val2) {
while (my ($key4, $val4) = each %$val3) {
print "\t\t\$key4 = $key4 => $val4\n";
}
print "\n";
}
}
}

Answer 3

[Edit I typed too slowly while answering, so this response bascially duplicates #mpapec's below - I will leave the references here and you can vote me up for those ;-) but do not accept my response as the answer].
Try something like the following to see if it works:
for $inner_hash (#{ $data1->{Family}{House} }) {
say "Name: $inner_hash->{Name}"
}
since you need to get the inner hashes' values from inside the elements of the array (that is what value:ARRAY(OXXX) is telling you).
You can use perldoc to look at the perldata, perlref, perlreftut and perldsc PODs to learn more about data structures and dereferencing. If keeping your data structure in mind while you are writing code gets to be too hard to do, it may mean you need to simplify things: either the data itself or by writing sub's to make it easier to access, or making use some of the excellent utility modules from CPAN.
There's also some good perl data structure related tutorials out there. The POD/perldoc documentation that ships with perl (along with Chapter 9 of Programming Perl) is the canonical reference, but you might browse these nodes from perlmonks:
References quick reference
Referencing in advanced data structures
Visualizing perl data structures
Perlmonks Hash Tutorial
NB Above I'm using the perlcritic and Perl Best Practices style of dereferencing: e.g.: #{ $data1->{Family}{House} } so the syntax reminds me that the inner hashes (or inner-inner?) are inside an array. There's a cool new way of dereferencing being introduced in perl 5.20 called postfix dereferencing which will be great, but you can't go wrong following the recommendations of PBP.
"Until you start thinking in terms of hashes, you aren't really thinking in Perl." -- Larry Wall
Cheers,