curl command line equivalent to this perl code - perl

Question

I want to write a curl command for a POST request equivalent to this Perl code:
use strict;
use warnings;
use LWP::UserAgent;
my $base = 'http://www.uniprot.org/mapping/';
my $params = {
from => 'ACC',
to => 'P_REFSEQ_AC',
format => 'tab',
query => 'P13368'
};
my $agent = LWP::UserAgent->new();
push #{$agent->requests_redirectable}, 'POST';
my $response = $agent->post($base, $params);
$response->is_success ?
print $response->content :
die 'Failed, got ' . $response->status_line .
' for ' . $response->request->uri . "\n";
I tried with (and many other variants) :
curl -X POST -H "Expect:" --form "from=ACC;to=P_REFSEQ_AC;format=tab; query=P13368" http://www.uniprot.org/mapping/ -o out.tab
The Perl code retrieves the expected result, but the curl command line does not. It retrieves the web page from "http://www.uniprot.org/mapping/" but does not make the POST request.
I looked for an error in the response header, but didn't find anything suspicious.
> POST http://www.uniprot.org/mapping/ HTTP/1.1
> User-Agent: curl/7.22.0 (x86_64-pc-linux-gnu) libcurl/7.22.0 OpenSSL/1.0.1 zlib/1.2.3.4 libidn/1.23 librtmp/2.3
> Host: www.uniprot.org
> Accept: */*
> Proxy-Connection: Keep-Alive
> Content-Length: 178
> Content-Type: multipart/form-data; boundary=----------------------------164471d8347f
>
} [data not shown]
* HTTP 1.0, assume close after body
< HTTP/1.0 200 OK
< Server: Apache-Coyote/1.1
< Vary: User-Agent
< Vary: Accept-Encoding
< X-Hosted-By: European Bioinformatics Institute
< Content-Type: text/html;charset=UTF-8
< Date: Wed, 05 Aug 2015 20:32:00 GMT
< X-UniProt-Release: 2015_08
< Access-Control-Allow-Origin: *
< Access-Control-Allow-Headers: origin, x-requested-with, content-type
< X-Cache: MISS from localhost
< X-Cache-Lookup: MISS from localhost:3128
< Via: 1.0 localhost (squid/3.1.20)
< Connection: close
<
I spent almost three days looking for a solution in the web, but nothing is working for me.

Answer 1

It looks like the server expects the data as application/x-www-form-urlencoded and not as multipart/form-data as you do with the --form argument. The following should work:
curl -v -L --data \
"from=ACC&to=P_REFSEQ_AC&format=tab&query=P13368" \
http://www.uniprot.org/mapping/ -o out.tab
With --data you get the expected content-type header, but you must do the encoding yourself. With -L curl follows a redirect which is needed here to get the resulting data.
The -X POST option is not needed since POST is the default method when sending data. And -H "Expect:" is not needed either.