Why does LWP::UserAgent succeed and Mojo::UserAgent fail? - perl

Question

If I make a request like this:
my $mojo_ua = Mojo::UserAgent->new->max_redirects(5);
$mojo_ua->inactivity_timeout(60)->connect_timeout(60)->request_timeout(60);;
$mojo_ua->transactor->name('Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36');
my $headers = {
'Accept' => 'application/json',
'Accept-Language' => 'en-US,en;q=0.5',
'Connection' => 'keep-alive',
'User-Agent' => 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36',
'x-csrf-token' => 'Fetch',
'Accept-Encoding' => 'gzip, deflate, br',
'DataServiceVersion' => '2.0',
'MaxDataServiceVersion' => '2.0',
'Referer' => 'https://blah.blas.com/someThing.someThing'
};
my $url = Mojo::URL->new('https://blah.blah.com/irj/go/sap/FOO_BAR_BAZ/');
my $tx = $mojo_ua->get($url, $headers);
$tx = $mojo_ua->start($tx);
my $res = $tx->result;
the request times out, but if I take the exact same request, built in the same way and do this:
my $lwp_ua = LWP::UserAgent->new;
my $req = HTTP::Request->parse( $tx->req->to_string );
$req->uri("$url");
my $res = $lwp_ua->request($req);
it succeeds.
It happens in a few cases that Mojo::UserAgent fails, and LWP::UserAgent succeeds with exactly the same transaction, and I'm starting to get curious.
Any idea as to why?

Answer 1

Your call to
$mojo_ua->get($url, $headers)
has already sent the HTTP request and received the response from the server, errored, or timed out. You don't need to call
$mojo_ua->start($tx)
as well, and that statement should be removed
If you really want to first build the transaction and then start it, you need
my $tx = $mojo_ua->build_tx(GET => $url, $headers);
$tx = $mojo_ua->start($tx);
but I don't see any reason why you should need to do it this way