CODEWITHSUNDEEP
arraysjsonperl
Jeff
Jeff

Reputation: 179

Creating a JSON array containing multiple variables

I want to modify my Perl script to output a list of variables using the json_encode function, but I'm not sure how.

Here's the output of my unmodified Perl script:

Vicia_sativa = Vicia_sativa.png 
Geranium_maculatum = Geranium_maculatum.png 
Narcissus_pseudonarcissus = Narcissus_pseudonarcissus1.png Narcissus_pseudonarcissus2.png 
Polygonum_persicaria = Polygonum_persicaria1.png Polygonum_persicaria2.png 
Corylus_americana = Corylus_americana1.png Corylus_americana2.png

The variables to the left of the equal signs are plant names, and the one or more file names to the right of the equal signs are plant photos. Notice that these file names are not separated by commas.

Here's my Perl script that generated the above output:

#!/usr/bin/perl
use strict;
use warnings;
use English;   ## use names rather than symbols for special variables

my $dir = '/Users/jdm/Desktop/xampp/htdocs/cnc/images/plants';

opendir my $dfh, $dir  or die "Can't open $dir: $OS_ERROR";
my %genus_species;  ## store matching entries in a hash

for my $file (readdir $dfh)
{
    next unless $file =~ /.png$/;  ## entry must have .png extension
    my $genus = $file =~ s/\d*\.png$//r;
    push(@{$genus_species{$genus}}, $file);   ## push to array,the @{} is to cast the single entry to a reference to an list
}

for my $genus (keys %genus_species)
{
    print "$genus = ";
    print "$_ " for sort @{$genus_species{$genus}}; # sort and loop though entries in list reference
    print "\n";
}

Please advise how to output these variables in a JSON array. Thanks.

Update... Here's the revised script with the recommended changes per a forum member:

#!/usr/bin/perl
use strict;
use warnings;

use JSON::PP;

use English;   ## use names rather than symbols for special variables

my $dir = '/Users/jdm/Desktop/xampp/htdocs/cnc/images/plants';

opendir my $dfh, $dir  or die "Can't open $dir: $OS_ERROR";
my %genus_species;  ## store matching entries in a hash

for my $file (readdir $dfh)
{
    next unless $file =~ /.png$/;  ## entry must have .png extension
    my $genus = $file =~ s/\d*\.png$//r;
    push(@{$genus_species{$genus}}, $file);   ## push to array,the @{} is to cast the single entry to a reference to an list
}

print(encode_json(\%genus_species));

This revised code works! However, the file names are no longer sorted. Any ideas how to incorporate sort into the encode_json function?

Upvotes: 1

Views: 167

Answers (1)

sticky bit
sticky bit

Reputation: 37472

Pretty straight forward actually... You can use the JSON::PP module and pass a reference of your hash to encode_json().

#!/usr/bin/perl

use strict;
use warnings;

use JSON::PP;
# your other code goes here...

# instead of `for my $genus (keys %genus_species) { ... }` do:
print(encode_json(\%genus_species));

Upvotes: 3

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