Ending a controller with a get_p call

[daleif]

This has been annoying me for a while now, and it bugs me that it is listed in the FAQ, but with no explanation on how to solve it.

Say I have controller that is suppose to fetch a page online, get some info and return some JSON. Why does this not work (I replaced the return statements with

sub extract ($self) {
  my $url   = 'SOM EURL';
  my $ua    = Mojo::UserAgent->new->inactivity_timeout(15)->max_redirects(5);

  $self->render_later;
  
  return $ua->get_p($url)
      ->then(sub ($tx)  {
		 $self->log->info($self->dumper($tx));
                 return $self->render(json => {title => 'test'});
	     })
      ->catch( sub ($err) {
		   $self->log->error($err);
                  return $self->render(json => undef);
	       })->wait;
}

I keep getting "Premature connection close". I get that something runs out of scope. But when what exactly is the paradigm we should use for something like this?

[kraih]

You need to prevent $ua from going out of scope. Store it in a helper or so.

[daleif]

It would be nice if there were an example of a solution do such a thing somewhere in the documentation.

I added an our variable in my plugin where i store my helpers and made a helper that just sets that variable to $ua. That works. Using a my variable did not.

[Grinnz]

https://docs.mojolicious.org/Mojolicious/Guides/FAQ#What-does-Premature-connection-close-mean

[Grinnz]

Alternatively to an our variable, you can store the $ua in a helper or at a higher scope in the file.

[daleif]

I know I've read it, but it has now good suggestions for solutions.

I did try storing it in a helper, but that gave the same result, hence the our.

[hussam-qasem]

Perhaps something like this?

use Mojolicious::Lite -signatures, -async_await;

helper my_ua => sub {
  use Mojo::UserAgent;
  my $ua = Mojo::UserAgent->new->inactivity_timeout(15)->max_redirects(5);
  $ua
};

any '/' => async sub ($c) {
    my $url = Mojo::URL->new('https://httpbin.org/json');
    $c->render_later();
    my $results = await Mojo::Promise->all_settled( $c->my_ua->get_p( $url ) );
    if ($results->{status} eq "fulfilled") {
      my $tx = $results->{value}[0];
      my $json = $tx->res->json;
      $c->render(json => $json);
    }
    else {
      my $reason = $results->{reason}[0];
      $c->render(json => {reason => $reason});
    }
};

app->start;

Also, if you're proxying requests consider the proxy helper.

[daleif]

Very interesting and a better helper than what I was doing ;-) Will do some tests.

[hussam-qasem]

You can also use the built-in user agent, e.g. $c->ua->get_p( $url ) and control parameter using environment variables.

[daleif]

I thought I read somewhere that one should not mess with $c->ua.
BTW: do you have any ideas for #2090

[hussam-qasem]

It's there in the docs