Following this useful Advent about Dancer::Exception:

 

 

I am attempting to refactor exception handling in a large D1 app, using Dancer::Exception. 

 

Ideally I’d like to Raise Friendly => ‘Some Friendly Error Message’ to report user-friendly error messages without logging, and everything else (whether raised by Dancer, die(), or by something else such as a database error) should just report “Internal Server Error” and log it.

 

Furthermore, I’d like to be able to use Raise Friendly => ‘Some Friendly Error Message’ anywhere within the route code or within any package used by the route (example below uses Some::Package).

 

See code below.  It *appears* to work for all shown cases (1, 2, 3a-3d), but I would really appreciate critique and recommendations.  In particular:

 

1. I don’t want to repeat the same catch {} section within every single route (following principles of D.R.Y.), so would really appreciate recommendations for cleanup.  I tried using hook before_error_init and before_error_render but got nowhere fast (maybe I shouldn’t have given up?)

 

2. Am I using register_exception(‘Friendly’); correctly?  I get a compilation error if I attempt to register_exception(‘Friendly’); within Some::Package. 

 

3. Following D.R.Y., it would be nice to not have to register_exception(‘Friendly’) in every single route.  I tried declaring it within app.pl but got the expected compilation error.

 

Thanks all,

Hermann

 

---

 

package mytest;

use strict;

use Dancer ':syntax';

use Dancer::Exception qw(:all);

register_exception('Friendly');

use lib "/home/s1/modules";

use Some::Package;

 

get '/' => sub {

 

  try {

 

    # Case 1

    Raise Friendly => ‘Friendly within mytest’;

 

    # Case 2

    die ‘Unfriendly within my test’;

 

    # Case 3a-3d

    &Some::Package::Test();

 

    }

   catch {

    my ($exception) = @_;

    if (ref($exception) =~ /^Dancer\:\:Exception/) {

      if ($exception->does('Friendly')) {

        status 400;

        return "got a friendly exception: " . $exception->message;

        }

      warning 'got an unknown exception to rethrow';

      $exception->rethrow;

      }

    die $exception;

    };

};

 

 

 

----

 

package Some::Package;

use Dancer ':syntax';

use Dancer::Plugin::Database;

use Dancer::Exception qw(:all);

return –1;

 

sub Test {

 

  # Case 3a:

  raise Friendly => 'A friendly error within Some::Package’;

 

  # Case 3b:

  die ‘Unfriendly within Some::Package’;

 

  # Case 3c: database error (unfriendly)

  database(‘mydb’)->selectrow_array("SELbarfECT 1");

 

  # Case 3d: Some other package

  &Some::Other::Package::Test();

 

};

 

 

-----

 

And for completeness, app.pl:

 

use strict;

use Dancer;

use mytest;

dance;