POST request problem

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

Hi Monks, I am trying to send a POST request using LWP::UserAgent and HTTP::Request. The example I was given looks a bit weird to me but this is it:

POST /endpoint?user=yyy&pass=zzz HTTP/1.1
Host: api.xxx.com
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary7MA4
+YWxkTrZu0gW

----WebKitFormBoundary7MA4YWxkTrZu0gW
[download]

This is the code I have tried:

my $url = 'https://api.xxx.com/endpoint?user=yyy&pass=zzz';
my $request = HTTP::Request->new( 'POST', $url );
$request->content_type('multipart/form-data');
print $request->as_string;
my $response = $ua->request($request);
print $response->as_string;
[download]

The request

POST https://api.xxx.com/endpoint?user=yyy&pass=zzz
Content-Type: multipart/form-data
[download]

The response:

HTTP Error 411. The request must be chunked or have a content length.
[download]

How can I get HTTP::Request to do this. I tried giving it a content of empty string but no different. TIA for any help

Comment on POST request problem Select or Download Code

Replies are listed 'Best First'.
Re: POST request problem by Corion (Patriarch) on Jun 03, 2016 at 13:31 UTC
Have you considered giving a `Content-Length` header?	[reply] [d/l]
Re^2: POST request problem by bangor (Monk) on Jun 03, 2016 at 13:37 UTC
I did try `$request->content_length(0);` but then got "Not Found". Thing is there is no content. From research I saw something about a header "Transfer-Encoding: chunked" but I can't seem to set that.	[reply] [d/l]
Re^3: POST request problem by Corion (Patriarch) on Jun 03, 2016 at 13:41 UTC
Have you looked at what exactly you are sending now? I would suspect that whatever "not found" error you're getting now is the next step. Personally, I don't know how to make LWP::UserAgent send content in a "chunked" encoding. Maybe consider first simply `print`ing directly all the headers and body yourself if you want to follow up that avenue.	[reply] [d/l]
Re^4: POST request problem by bangor (Monk) on Jun 03, 2016 at 13:54 UTC
Re^5: POST request problem by Corion (Patriarch) on Jun 03, 2016 at 14:11 UTC
Re: POST request problem by Anonymous Monk on Jun 04, 2016 at 00:36 UTC
Yeah , when you figure out what you really need, see one of these HTTP::Request::StreamingUpload, Re: PUT a Multipart request in PERL ( lwp-mechanize-put-multipart-form.pl ), Re^2: POST'ing a large File with LWP::UserAgent, Re^2: file download with connection problems, HTTP::Request::StreamingUpload,	[reply]
Re: POST request problem by hippo (Archbishop) on Jun 03, 2016 at 15:49 UTC
Unless I'm missing something obvious, your POST request has no payload, unlike the sample you've been given, ie. you never call the `content` method of your request object to set the data. This may be all that is required.	[reply] [d/l]
Re^2: POST request problem by bangor (Monk) on Jun 03, 2016 at 16:07 UTC
Hi hippo, you may have missed last line of my original question - I tried giving it a content of an empty string but it did not generate the boundary in the header and body which is what I think is necessary. The example I was given comes from the Postman app - if you put a URL in and then choose "multipart/form-data" that is the request it generates. I am trying to duplicate that.	[reply]
Re^3: POST request problem by hippo (Archbishop) on Jun 03, 2016 at 16:14 UTC
Yes, somehow missed reading that, thanks. However, I would recommend giving it some actual content (not an empty string). Do the folks running the server not suggest what the POSTed content should be? There is little point to a POST request with no content.	[reply]
Re^4: POST request problem by bangor (Monk) on Jun 03, 2016 at 16:35 UTC
Re^3: POST request problem by RonW (Parson) on Jun 03, 2016 at 22:04 UTC
Adding to what hippo said, from RFC 2616: The POST method is used to request that the origin server accept the entity enclosed in the request as a new subordinate of the resource identified by the Request-URI in the Request-Line. So, many webservers require that POST requests have actual content. However, it's up to whomever designed/implemented the handler pointed to by the URI to describe what that content should be.	[reply]
Re^3: POST request problem by Anonymous Monk on Jun 04, 2016 at 00:11 UTC
but it did not generate the boundary in the header and body which is what I think is necessary. Its highly unlikely it would be necessary (highly unlikely), but anything is possible (stupid servers exist) Server should only care about "content", the chunked/boundary stuff is just ways to deliver "content", only some kind of http test server would "require" that type of request	[reply]
Re: POST request problem by papidave (Pilgrim) on Jun 06, 2016 at 13:40 UTC
When I use LWP, I use the post() method instead of directly constructing the HTTP::Request object myself, and have never run into any issues. The Content for your request should be the user and pass arguments from your URL -- which, as a side effect, keeps the web server from logging user account info into its access log. I suspect that's the reason you wanted to POST in the first place. In any case, this would give you something like the following: `#!/usr/bin/perl -w use strict; use LWP::UserAgent; my $auser = 'jebediah'; # kerman my $apwd = 'KSP#bada55'; # green my $page = 'http://api.xxx.com/endpoint'; my @args = ( user => $auser, pass => $apwd ); my $agent = new LWP::UserAgent(); die "couldn't create agent\n" unless $agent; my $response = $agent->post( $page, Content => \@args ); die "couldn't post web page\n" unless $response; # process $response->header() here if desired. print $response->content(), "\n";` [download] UPDATE: cleaned up the account info so i'm not hard-coding @args as much.	[reply] [d/l]