Dancer::Serializer: content deserialization fails silently instead of yielding an error

[a-adam]

reopening issue #977, the suggested code to catch deserialization errors does not work.

post '/foo' => sub {
   my $data = params('body') or die "couldn't deserialize " . request()->body;
};

there is no such params('body') on successful deserialization. also, no param('body').
i do not see a safe way to detect such failures at this time -- especially since parameters
get merged together from URL and content.
hence, it would be necessary to try to deserialize manually to see if it fails...

IMO still, the right fix is to return 400 or a 4xx (suggesting it should be 500 was, of course, a mistake).

[yanick]

Does too:

$ cat foo.pl
use Dancer;

use strict;
use warnings;

set serializer => 'JSON';

post '/' => sub {
    return join( ' ', params('body') ) || "deserialization failed";
};

dance;

$ perl foo.pl &
>> Dancer 1.3123 server 3532 listening on http://0.0.0.0:3000
== Entering the development dance floor ...

$ curl -H "Content-Type: application/json" -X POST -d '{ "foo": 1 }' http://0.0.0.0:3000/
foo 1⏎                                                                                         

$ curl -H "Content-Type: application/json" -X POST -d 'banana' http://0.0.0.0:3000/
deserialization failed⏎ 

But I see the usefulness of a "die if deserialization failed". I'll try to merge that in as an option.