Accessing a nested data structure - perl

Question

I have an array of hashes nested to multiple levels. I need to extract a value from all deeply-nested hashes that have a given value for a different key in the same hash
This is a collection of entities from our database, and the data represents contacts within each entity and all of their contact values.
There is a hash key contact_method_type_id which refers to an integer defining the type of contact method. The contact_method_type_id that I care about is 1, which is email.
The first contact has three different contact_methods. The first is 4 which is an office phone, the second is a 2 which is a home phone, and the third is a 1 which is email.
Within the same hash is there is a 'contact_method_value', which is the string representation of their email address.
I need a way to extract just these values into a new array
Here are the contents of the first element of the array
$VAR1 = [
{ 'total' => '2',
'results' => [
{ 'contact_type_name' => 'Primary Technical Contact',
'street' => undef,
'state_id' => undef,
'state_name' => undef,
'last_name' => 'Barb',
'entities' => [
{ 'entity_name' => 'XXXXX',
'entity_id' => 'XXXXX'
}
],
'state_abbr_name' => undef,
'city' => undef,
'country_id' => undef,
'latitude' => undef,
'contact_id' => 'XXXXXX',
'contact_type_id' => '1',
'roles' => [],
'contact_methods' => [
{ 'entity_name' => undef,
'contact_method_value' => 'XXXXXXX',
'contact_method_type_id' => '4',
'contact_method_id' => '24041',
'entity_id' => undef,
'contact_method_type_name' => 'Cell Phone'
},
{ 'entity_name' => undef,
'contact_method_value' => 'XXXXXX',
'contact_method_type_id' => '2',
'contact_method_id' => '24051',
'entity_id' => undef,
'contact_method_type_name' => 'Office Phone'
},
{ 'entity_name' => undef,
'contact_method_value' => 'example#example.com',
'contact_method_type_id' => '1',
'contact_method_id' => '24061',
'entity_id' => undef,
'contact_method_type_name' => 'Email'
}
],
'country_name' => undef,
'longitude' => undef,
'country_abbr_name' => undef,
'full_name' => 'NAME',
'networks' => [
{ 'network_name' => 'NET',
'network_id' => 'X'
}
],
'timezone_id' => undef,
'zip' => undef,
'timezone_name' => undef,
'title' => 'MAC/Network Specialist',
'first_name' => 'Terri'
},
{ 'contact_type_name' => 'Primary Technical Contact',
'street' => 'STREET',
'state_id' => undef,
'state_name' => undef,
'last_name' => 'NAME',
'entities' => [
{ 'entity_name' => 'NAME',
'entity_id' => '2679'
}
],
'state_abbr_name' => undef,
'city' => 'CITY',
'country_id' => undef,
'latitude' => undef,
'contact_id' => '7896',
'contact_type_id' => '1',
'roles' => [],
'contact_methods' => [
{ 'entity_name' => undef,
'contact_method_value' => 'example#example.com',
'contact_method_type_id' => '1',
'contact_method_id' => '16796',
'entity_id' => undef,
'contact_method_type_name' => 'Email'
},
{ 'entity_name' => undef,
'contact_method_value' => 'number',
'contact_method_type_id' => '2',
'contact_method_id' => '16797',
'entity_id' => undef,
'contact_method_type_name' => 'Office Phone'
}
],
'country_name' => undef,
'longitude' => undef,
'country_abbr_name' => undef,
'full_name' => 'NAME',
'networks' => [
{ 'network_name' => 'net',
'network_id' => '17'
}
],
'timezone_id' => undef,
'zip' => 'zip',
'timezone_name' => undef,
'title' => 'Infrastructure Manager',
'first_name' => 'name'
}
],
'offset' => '0'
},
...

Answer 1

This looks suspiciously like something that XML::Simple would have generated.
Assuming this is the case, then I would suggest that you've fallen for the classic mistake of assuming XML::Simple actually helps.
Under that assumption, if you instead use XML::Twig:
Taking your $VAR1. Although - ideally you'll just parse the original source with parse or parsefile:
use XML::Twig;
use XML::Simple;
my $twig = XML::Twig->parse( XMLout($VAR1) );
print $_->att('contact_method_value'), "\n" for $twig->findnodes('//contact_methods[#contact_method_type_name="Email"]');
Which given your sample (as $VAR1):
example#example.com
example#example.com
Edit: Because you've commented that it's JSON then I wouldn't necessarily do this (Although - it does actually work, despite that).

Answer 2

If the data structures are all of the same kind, this is very trivial. You just need to iterate all the outer hashrefs (I called those resultsets). Inside those, you need to look at all results, and in each result you need to look at all the contact methods. If one of them has a contact_method_type_id of 1, you take the contact_method_value. And that's it.
my #email_addresses;
foreach my $resultset ( #{$data} ) {
foreach my $result ( #{ $resultset->{results} } ) {
foreach my $contact ( #{ $result->{contact_methods} } ) {
push #email_addresses , [ $contact->{contact_method_value} ]
if $contact->{contact_method_type_id} == 1;
}
}
}
This code assumes your structure is called $data. #email_addresses looks like this when output.
[
[ 'EMAIL' ],
[ 'EMAIL' ]
];

Answer 3

If you have this on a database then you should use an SQL query to retrieve it, rather than fetching everything into memory and processing what you have
The output from Data::Dumper shows the contents of your data, but it doesn't explain what you're dealing with in your code. Specifically, you don't have a $VAR1 in your code, but I have no idea what you do have
In the end, I think I wouldn't start from here. But since it's the only starting point I have to work with, it's a simple matter of recursing through the data structure
I've assumed that you want
$VAR1->[*]{results}[*]{contact_methods}[*]{contact_method_value}
where
$VAR1->[*]{results}[*]{contact_methods}[*]{contact_method_type_name} eq 'Email'
Update
Since your comments I've altered my code to select the same values where
$VAR1->[*]{results}[*]{contact_methods}[*]{contact_method_type_id} == 1
Since you said nothing about your code at all, I've had to assume a variable $data which contains a reference to the array that you show in your question
for my $item ( #$data ) {
my $results = $item->{results};
for my $result ( #$results ) {
my $methods = $result->{contact_methods} or die;
for my $method ( #$methods ) {
#my $type_name = $method->{contact_method_type_name};
#next unless $type_name eq 'Email';
my $type_id = $method->{contact_method_type_id};
next unless $type_id == 1; ## Email
my $value = $method->{contact_method_value};
print "$value\n";
}
}
}
output
example#example.com
example#example.com