How do I make curl to POST a parameter, reading its value from a file? - http

Question

I’m playing with GitHub web hooks and I want to use curl to post some sample JSON. The request is supposed to contain a payload POST parameter with the JSON string as a value. As an example, this works:
$ curl --form payload='{"foo":1}' http://somewhere
But I need to read the JSON from a file (say foo.json). Replacing the JSON string by #foo.json posts the payload in the request body:
--------------------------8d0c6d3f9cc7da97
Content-Disposition: form-data; name="payload"; filename="foo.json"
Content-Type: application/octet-stream
{'foo':1}
--------------------------8d0c6d3f9cc7da97--
That’s not really what I want, I need the payload to be passed as a parameter. How do I do that?

Answer 1

Maybe silly but try this:
cat foo.json | xargs -I % curl --form payload='%' http://example.com
Just wrote this little thing and it worked:
var=`cat some.json` && curl --form payload="$var" http://lvh.me/test/index.php

Answer 2

Here’s an alternative Perl testing script. Pass the target URL as the first argument, feed the JSON to STDIN:
#!/usr/bin/env perl
use strict;
use warnings;
use LWP;
my $target = shift #ARGV or die "Need a target URL";
my $ua = LWP::UserAgent->new;
my $payload = do { local $/; <STDIN> };
my $response = $ua->post($target, { payload => $payload });
print $response->as_string;