[Dancer-users] raising exceptions in hooks.

[damien krotkine]

Hi,

Thanks for using exceptions :)

I'm having a look at this issue. There is indeed a "catch all" mechanism to
produce a Dancer::halt in case of any issue in hooks. I'll make it more
flexible.


On 28 February 2012 05:22, Rusty Conover <rconover at infogears.com> wrote:

> Hi Everyone,
>
> I'm trying to use a hook like:
>
> register_exception('DatabaseProblem', message_pattern => "Database
> problem: %s");
>
> hook 'database_error' => sub {
>  my $message = Carp::longmess($_[0]);
>  my $handle = shift;
>  raise DatabaseProblem => $message;
>  return;
> };
>
> This is documented in Dancer::Plugin::Database.
>
> To raise a DatabaseProblem exception in the event of a database error such
> as:
>
> my $dbh = database();
> try {
>   $dbh->do("insert into table_that_does_not_exist values(?)", undef,
> "yes");
> } catch {
>   my ($exception) = @_;
>   if ($exception->does('DatabaseProblem') {
>       # do something
>   }
> };
>
> The problem I'm getting is:
>
> An error occured while executing the filter named database_error:
>
> It seems we can't raise an exception in the database_error hook or any
> hook really, without having it generate a 500 error because Dancer::Hook
> catches all exceptions thrown in hooks and halts rendering.
>
> Relevant excerpt from Hook.pm:
>
> my $compiled_filter = sub {
>      my @arguments = @_;
>      return if Dancer::SharedData->response->halted;
>
>      my $app = Dancer::App->current();
>      return unless $properties->should_run_this_app($app->name);
>
>      Dancer::Logger::core( "entering " . $hook_name . " hook" );
>
>
>      try { $code->(@arguments) }
>      catch {
>          my ($exception) = @_;
>          # exception is not a workflow continuation but a genuine error
>          my $err = Dancer::Error->new(
>              code    => 500,
>              title   => $hook_name . ' filter error',
>              message => "An error occured while executing the filter named
> $hook_name: $exception",
>              exception => $exception,
>          );
>          # raise a new halt exception
>          Dancer::halt( $err->render );
>      };
>  };
>
> Can we change this so exceptions can be raised from hooks, or is there
> another pattern I should be using to catch DBI errors?
>
> Many thanks,
>
> Rusty
> --
> InfoGears Inc.
> http://www.infogears.com
> http://www.gearbuyer.com
>
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