如何从 Perl 数据结构中获取数据

Question

I've parsed JSON into the following data structure:

$VAR1 = {
          '041012020' => {
                            'item_number' => 'P2345'
                          },
          '041012021' => {
                            'item_number' => 'I0965'
                          },
          '041012022' => {
                            'item_number' => 'R2204'
                          }
        };

I'm trying to get the values of item_numbers using the following code, and it's giving me the HASH Values as output rather than the actual item_number values. Please guide me to get the expected values.

foreach my $value (values %{$json_obj}) {
       say "Value is: $value,";
 }

Output:

Value is: HASH(0x557ce4e2f3c0),
Value is: HASH(0x557ce4e4de18),
Value is: HASH(0x557ce4e4dcf8),

If I use the same code to get the keys it's working perfectly fine

foreach my $key (keys %{$json_obj}) {
        say "Key is: $key,";
 }

Output:

Key is: 041012020,
Key is: 041012020,
Key is: 041012022,

Answer 1

The values of the hash elements are references to hashes ( { item_number => 'P2345' } ). That's what you get when you stringify a reference. If you want the item number, you'll need to tell Perl that.

for my $value (values %$data) {
   say $value->{item_number};
}

or

for my $item_number ( map { $_->{item_number} } values %$data ) {
   say $item_number;
}

Answer 2

Here is the short code for your question.

    #!usr/bin/perl
    
    $VAR1 = {
              '041012020' => {
                                'item_number' => 'P2345'
                              },
              '041012021' => {
                                'item_number' => 'I0965'
                              },
              '041012022' => {
                                'item_number' => 'R2204'
                              }
            };
            
    print "$VAR1->{$_}->{item_number}\n" for keys %$VAR1;

To use for in a block:

for my $key (keys %$VAR1) {
    print "$VAR1->{$key}->{item_number}\n"
}