Error response when POSTing JSON with PERL - json

Question

I wrote a small PERL script to fetch some data from an URL using PERL. Not being an experienced programmer, I used the examples I found here in Stackoverflow. However, I always get the response
{"error":{"code":2,"message":"post parameter request missing"}}
The script looks like this
my $uri = 'URL';
my $json = '{"sourceCountry":"DE","sourceStore":476,"targetCountry":"DE","targetStore":[869],"article":[110101]}';
my $req = HTTP::Request->new( 'POST', $uri );
$req->header( 'Content-Type' => 'application/json' );
$req->content( $json );
my $lwp = LWP::UserAgent->new;
$response = $lwp->request($req);
The complete response is this:
HTTP/1.1 200 OK
Connection: close
Date: Wed, 15 Jan 2014 14:29:06 GMT
Server: Apache
Content-Length: 63
Content-Type: application/json; charset=utf-8
Client-Date: Wed, 15 Jan 2014 14:29:06 GMT
Client-Peer: 10.200.10.74:80
Client-Response-Num: 1
X-Powered-By: PHP/5.3.3
{"error":{"code":2,"message":"post parameter request missing"}}
What did I wrong?

Answer 1

Try:
use HTTP::Request::Common 'POST';
my $lwp = LWP::UserAgent->new;
$lwp->request( POST $uri, 'Content-Type' => 'application/json', 'Content' => $json );
though that should do basically the same thing except also setting Content-Length.
Alternatively, if the error you mention is literally indicating there is supposed to be a POST parameter (aka form data parameter) named request, try:
use HTTP::Request::Common 'POST';
my $lwp = LWP::UserAgent->new;
$lwp->request( POST $uri, [ 'request' => $json ] );

Answer 2

Assuming that it is a JSON RPC 2 service that you are trying to contact, you are missing part of the structure.
my $json = '{
"jsonrpc":"2.0",
"id":1,
"method":"some-method",
"params":{"sourceCountry":"DE","sourceStore":476,"targetCountry":"DE","targetStore":[869],"article":[110101]}
}';
If it is a JSON RPC service you could use JSON::RPC::LWP; which combines LWP::UserAgent and JSON::RPC::Common. It uses Moose so there will be quite a few dependencies to install. ( It uses Moose because JSON::RPC::Common uses Moose. )
use JSON::RPC::LWP;
my $url = ...;
my $rpc = JSON::RPC::LWP->new(
agent => 'Example ',
);
my $response = $rpc->call(
$url, # uri
'some-method', # service
{
sourceCountry => "DE",
sourceStore => 476,
targetCountry => "DE",
targetStore => [869],
article => [110101],
} # JSON container
);
if( my $error = $response->error ){
print 'error: #', $error->code, ' "', $error->message, "\"\n";
}else{
print "success!\n";
use Data::Dumper;
print Dumper( $response->result );
}
Note that you don't give JSON::RPC::LWP a JSON string, you give it a data structure.