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

Hi all,

I'm attempting to write a Perl script that can upload a file to a web server based on the following very simple file upload form (URL redacted):
<form enctype="multipart/form-data" action="http://example.com" method
+="post">
    <input type="file" size="50" name="file_0"/><br /><br />
    <input type="submit" value="Attach File(s)" name="confirm"/>
</form>

[download]

And here's my Perl code (URL, username, and password redacted): 
use strict;
use warnings;

use LWP::UserAgent;
use HTTP::Request::Common;

my $userAgent = LWP::UserAgent->new();
my $request = HTTP::Request->new(POST 'http://example.com', Content_Ty
+pe => 'multipart/form-data', Content => [file_0 => ['options2.txt']])
+;

$request->authorization_basic('username', 'password');
my $response = $userAgent->request($request);
print $response->error_as_HTML . "\n" if $response->is_error;

[download]

This gives me a 400 "URL missing" error from the web server. Quite frankly, I have no idea what I'm doing wrong. I'm not a Perl noob, but I've never had occasion to use LWP::UserAgent or HTTP::Request, so I'm a noob in that sense.

Any ideas what I'm doing wrong or how I can debug?

Replies are listed 'Best First'.
Re: File upload with LWP::UserAgent
by Joost (Canon) on Jun 12, 2008 at 23:08 UTC
    URL missing is not a webserver response, it signifies that you didn't pass the URL: 
    my $request = HTTP::Request->new(POST 'http://example.com', Content_Ty
+pe => 'multipart/form-data', Content => [file_0 => ['options2.txt']])
+;

    [download]

    You're missing => after POST. Which probably explains the immediate error: POST 'http://..' is seen as a function call (from HTTP:::Request::Common) instead of a string.

    AFAIK the content should be added using the content method, not as an argument to the constructor (since constructor arguments are all parsed as headers. See HTTP::Request

    Anyway, using WWW::Mechanize will probably be easier and make your code a bit more robust.

    "What should it profit a man, if he should win a flame war, yet lose his cool?"
[reply]
[d/l]
[select]
      Thanks for suggesting WWW::Mechanize. I'm getting a little further, but I think my problem now is that I can't get cookies working. When I authenticate, the appropriate page is returned, but the next page I request prompts me to log in again. Here's my code:
      use HTTP::Cookies;
use WWW::Mechanize;

my $cj = HTTP::Cookies->new( autosave => 1, ignore_discard => 1 );

my $mech = WWW::Mechanize->new( cookie_jar => $cj );

$mech->get( 'http://example.com/login.action' );

if ($mech->success())
{
    $mech->submit_form( form_name => 'loginform', fields => { os_usern
+ame => 'username', os_password => 'password' } );
}

if ($mech->success())
{
    $mech->follow_link( text => 'Training'); # This is where I get red
+irected to the login page again!
}

      [download]

      Am I using cookies improperly, or is there some other problem with my code?
[reply]
[d/l]
        I figured it out. The login form has a checkbox for remembering your username/password (as login forms often do). I simply had to use the tick() method to make sure that box was checked so that I could receive the login cookie and access subsequent pages.

        Thanks again for suggesting WWW::Mechanize!
[reply]
Re: File upload with LWP::UserAgent
by Anonymous Monk on Sep 16, 2008 at 14:28 UTC 
    ...

my $userAgent = LWP::UserAgent->new();
my $request = POST 'http://example.com', Content_Type => 'multipart/fo
+rm-data', Content => [file_0 => ['options2.txt']];

$request->authorization_basic('username', 'password');
my $response = $userAgent->request($request);
print $response->error_as_HTML . "\n" if $response->is_error;

    [download]
    would be correct, POST() creates HTTP::Request Object, making a HTTP::Request Object out of a HTTP::Request Object is nonsense.
[reply]
[d/l]

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