mojo streaming file upload

gistfile1.txt

use strict;
use warnings;
use Mojo::UserAgent;
use Mojo::Asset::File;
 
# Build a normal transaction
my $ua = Mojo::UserAgent->new;
my $tx = $ua->build_tx(POST => 'http://example.com');
 
# Prepare body
my $asset = Mojo::Asset::File->new(path => $file_path);
$tx->req->headers->content_type('video/x-msvideo');
$tx->req->headers->content_length(my $size = $asset->size);
 
# Start writing directly with a drain callback
my $drain;
my $start = 0;
$drain = sub {
  my $content = shift;
  my $chunk = $asset->get_chunk($start);
  $start += length $chunk;
  $drain = undef unless $start < $size;
  $content->write($chunk, $drain);
};
$tx->req->content->$drain;
 
# Process transaction
$tx = $ua->start($tx);