How can I have a Dancer2 before hook return an HTTP error?

lembark has asked for the wisdom of the Perl Monks concerning the following question:

Q: What can I use in a Dancer2 before hook to cause the request being processed to hand back an HTTP error?

Say I have a before hook that will filter out requests which are not worth processing. I would like to short-circuit the request and simply return, say, a 404. I've tried variations on bare return, returning a Dancer2::Core::Error object or the result of calling ->throw on one with no luck. I can abort with a 'die' but that leaves me returning a 500, not a 404 whatever. There is documentation in Dancer2 on handling errors generated by Dancer2 itself, but I cannot find anything that describes how to raise an error/exception/whatever from the Perl code running in handlers. The simplest example I can think of is a lightweight handler that rejects botched requests based on IP, username, etc, that are blacklisted.


hook before => sub
{
    ...
    is_bogus_request $request and ... # what???
};
[download]

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Re: How can I have a Dancer2 before hook return an HTTP error? by Arunbear (Prior) on Jan 25, 2025 at 13:12 UTC
From looking at the docs (and not tested): `hook before => sub { if ($some_condition) { send_error("Not allowed", 403); } };` [download] send_error halt (similar but more generic)	[reply] [d/l]
Re: How can I have a Dancer2 before hook return an HTTP error? by 1nickt (Canon) on Jan 26, 2025 at 12:37 UTC
Hi, First of all, as you may know, you don't need to code anything to get a 404 error response for a path that does not exist. `use strict; use warnings; use Dancer2; get '/' => sub { return 'Hello, world'; }; dance;` [download] `$ curl localhost:3000/does_not_exist` [download] `<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0 +, user-scalable=yes"> <title>Error 404 - Not Found</title> <link rel="stylesheet" href="http://localhost:3000/css/error.css"> </head> <body> <h1>Error 404 - Not Found</h1> <div id="content"> /does_not_exist </div> <div id="footer"> Powered by <a href="http://perldancer.org/">Dancer2</a> 1.1.2 </div> </body> </html>` [download] To return an error page based on something like an ID that is not allowed, use `send_error`: `use strict; use warnings; use Dancer2; get '/hello/:name' => sub { my $name = route_parameters->get('name'); return "Hello, $name"; }; hook before => sub { my $name = route_parameters->get('name'); is_disallowed($name) and send_error("$name is disallowed", 401); }; sub is_disallowed { my $name = shift; return $name eq 'nick' ? 1 : 0; } dance;` [download] `$ curl localhost:3000/hello/lembark` [download] `Hello, lembark` [download] `$ curl localhost:3000/hello/nick` [download] `<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0 +, user-scalable=yes"> <title>Error 401 - Unauthorized</title> <link rel="stylesheet" href="http://localhost:3000/css/error.css"> </head> <body> <h1>Error 401 - Unauthorized</h1> <div id="content"> nick is disallowed </div> <div id="footer"> Powered by <a href="http://perldancer.org/">Dancer2</a> 1.1.2 </div> </body> </html>` [download] See the documentation. Hope this helps update: included the before hook, d'oh The way forward always starts with a minimal test.	[reply] [d/l] [select]