error while converting json array to csv using perl - arrays

Question

im using a perl script to convert from JSON to csv. the sampple json is like this,
[{"id":100,
"primary-codes":["E0181V00","E0226V00"],
"substitute-codes":["E0181D00","E0226100"],
"fk-id":2294}]
and the perl code i used to convert this to csv is,
#!/usr/bin/perl
use utf8;
use warnings;
use strict;
use lib '.';
use JSON::PP qw(decode_json);
my $json;
{
local $/;
open my $fh, '<', 'output_array.json' or die $!;
$json = <$fh>;
}
my $perl = decode_json $json;
my $filename = 'sample.csv';
open(my $fh, '>>:encoding(UTF-8)', $filename) or die "Could not open file '$filename' $!";
say $fh 'nk_id,prim_cd,sub_cd,fk_id';
for (#$perl){
my $nk_id = '"' . $_->{"id"} . '"';
my $prim_cd= '"' . $_->{"primary-codes"} . '"';
my $sub_cd= '"' . $_->{"substitute-codes"} . '"';
my $fk_id= '"' . $_->{"fk-id"} . '"';
say $fh "$nk_id," . "$prim_cd," . "$sub_cd," . "$fk_id";
}
close $fh;
The output i get is like this,
nk_id,prim_cd,sub_cd,fk_id
100,ARRAY(0x201549f8),ARRAY(0x20154a88),2294
but i want it to be,
100,"E0181V00,E0226V00","E0181D00,E0226100",2294
i tried using ,
my $prim_cd = '"' . join ",", #{ $perl->[0]{"primary-codes"} } . '"';
But it just returns the count and not the elements.
Please help me out with this issue.
Thanks!

Answer 1

The one detail that subverted your honest attempt is the precedence. In
my $prim_cd = '"' . join ",", #{ $perl->[0]{"primary-codes"} } . '"';
the list #{ $perl->[0]...} is first concatenated (.) with ", and as the . operator imposes scalar context the number of elements in the list is used, yielding 2". Only then does join do its thing, "joining" the given list (which is a single element, 2")
Just add parenthesis
for (#$perl){
my $nk_id = '"' . $_->{"id"} . '"';
my $prim_cd = '"' . join(',', #{$_->{'primary-codes'}}) . '"';
my $sub_cd = '"' . join(',', #{$_->{'substitute-codes'}}) . '"';
my $fk_id = '"' . $_->{"fk-id"} . '"';
say $fh "$nk_id,$prim_cd,$sub_cd,$fk_id";
}
A few notes.
You forgot use feature qw(say); without which say won't work.
What is shown has no use of use utf8;, which is about the source file itself
What is shown doesn't need use lib; that specifies paths to be searched for modules. (It won't help in finding files, if that was the idea.). However, once we are at it ...
I avoid using . as it can create problems ranging from confusion to direct errors. For one, do you mean the current working directory, or the directory of the script? They aren't the same. Assuming that you use it for the script's directory (which it isn't), replace it with
use FindBin qw($RealBin);
use lib $RealBin;
To slurp a file you can also do
my $json = do {
local $/;
open my $fh, '<', 'output_array.json' or die $!;
<$fh>;
};