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POMultipart File Upload in Ruby
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copied!<p>I simply want to upload an image to a server with POST. As simple as this task sounds, there seems to be no simple solution in Ruby.</p> <p>In my application I am using <a href="http://mechanize.rubyforge.org/" rel="noreferrer">WWW::Mechanize</a> for most things so I wanted to use it for this too, and had a source like this:</p> <pre><code>f = File.new(filename, File::RDWR) reply = agent.post( 'http://rest-test.heroku.com', { :pict => f, :function => 'picture2', :username => @username, :password => @password, :pict_to => 0, :pict_type => 0 } ) f.close</code></pre> <p>This results in a totally garbage-ready file on the server that looks scrambled all over:</p> <blockquote> <p><a href="http://imagehub.org/f/1tk8/garbage.png" rel="noreferrer">alt text http://imagehub.org/f/1tk8/garbage.png</a></p> </blockquote> <p>My next step was to downgrade WWW::Mechanize to version 0.8.5. This worked until I tried to run it, which failed with an error like "Module not found in hpricot_scan.so". Using the Dependency Walker tool I could find out that hpricot_scan.so needed msvcrt-ruby18.dll. Yet after I put that .dll into my Ruby/bin-folder it gave me an empty error box from where on I couldn't debug very much further. So the problem here is that Mechanize 0.8.5 has a dependency on Hpricot instead of Nokogiri (which works flawlessly).</p> <hr> <p>The next idea was to use a different gem, so I tried using Net::HTTP. After short research I could find out that there is no native support for multipart forms in Net::HTTP and instead you have to build a class that encodes etc. for you. The most helpful I could find was the <a href="http://stanislavvitvitskiy.blogspot.com/2008/12/multipart-post-in-ruby.html" rel="noreferrer">Multipart-class by Stanislav Vitvitskiy</a>. This class looked good so far, but it does not do what I need, because I don't want to post <em>only</em> files, I also want to post normal data, and that is not possible with his class.</p> <hr> <p>My last attempt was to use <a href="http://rest-client.heroku.com/rdoc/" rel="noreferrer">RestClient</a>. This looked promising, as there have been examples on how to upload files. Yet I can't get it to post the form as multipart.</p> <pre><code>f = File.new(filename, File::RDWR) reply = RestClient.post( 'http://rest-test.heroku.com', :pict => f, :function => 'picture2', :username => @username, :password => @password, :pict_to => 0, :pict_type => 0 ) f.close</code></pre> <p>I am using <a href="http://rest-test.heroku.com" rel="noreferrer">http://rest-test.heroku.com</a> which sends back the request to debug if it is sent correctly, and I always get this back:</p> <pre>POST http://rest-test.heroku.com/ with a 101 byte payload, content type application/x-www-form-urlencoded { "pict" => "#<File:0x30d30c4>", "username" => "s1kx", "pict_to" => "0", "function" => "picture2", "pict_type" => "0", "password" => "password" }</pre> <p>This clearly shows that it does not use <code>multipart/form-data</code> as content-type but the standard <code>application/x-www-form-urlencoded</code>, although it definitely sees that <code>pict</code> is a file.</p> <hr> <p><strong>How can I upload a file in Ruby to a multipart form without implementing the whole encoding and data aligning myself?</strong></p>

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