How to Parse JSON from a URL in Perl

Question

I am trying parsing JSON from a website. I am having problem in parsing JSON. I am getting following error:

malformed JSON string, neither tag, array, object, number, string or atom, at character offset 0 (before "<html...") at D:\parser.pl line 45.

The URL is: https://coinmarketcap.com/coins

Any help would be appreciated. My code snippet is:

use strict;
use warnings;
use LWP::UserAgent;
use LWP::Simple;
use HTML::TreeBuilder;
use JSON;
use IO::Socket::SSL;
use Data::Dumper;

sub getJSON {
    my $url = $_[0] or die "URL missing!\n";
    
    my $ua = LWP::UserAgent->new(
    ssl_opts => {
        SSL_verify_mode => SSL_VERIFY_NONE(),
        verify_hostname => 0,
    }
);
    my $req = HTTP::Request->new( GET => $url );
$req->content_type('application/json');
my $res = $ua->request($req);

 die $res->status_line unless $res->is_success;

my $json = JSON->new();
my $json_text = $json->decode( $res->content );
}

The main problem with this code is that the URL you access does not actually return JSON. So the error message is fully correct - you are trying to interpret something as JSON which is not JSON. The fix is therefore to use the correct URL, whatever this is. Apart from that: setting a Content-Type header on a GET request does not make sense. This header describes the type of the content in the request body. But since this is a GET request there is no request body which also means that this none existing body has no type. — Steffen Ullrich
– Steffen Ullrich, Commented Mar 7, 2021 at 11:15
I found the solution myself. I scanned the HTML of website page with tree builder and extracted the tag containing json with tag ID. I got the whole json in one variable as a string. — P_Z
– P_Z, Commented Mar 7, 2021 at 13:03

P_Z · Accepted Answer · 2021-03-07 13:06:57Z

1

I found the solution myself. I scanned the HTML of the website page with tree builder (Perl API available on CPAN) and extracted the tag containing json with its tag ID. I got the whole json in one variable as a string.

answered Mar 7, 2021 at 13:06

P_Z

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