title: uploading a file to Rails JSON API server with Paperclip and Multipart request
body: <p>I want to upload a file from an Android client to a Rails JSON API server.</p>
  
  <p>I'm sending a Multipart/form request from the Android client which looks like that:</p>
  
  <pre><code>Content-Type: multipart/form-data; boundary=d99ArGa2SaAsrXaGL_AdkNlmGn2wuflo5
  Host: 10.0.2.2:3000
  Connection: Keep-Alive
  User-Agent: Apache-HttpClient/UNAVAILABLE (java 1.4)
  
  --d99ArGa2SaAsrXaGL_AdkNlmGn2wuflo5
  Content-Disposition: form-data; name="POSTDATA"
  Content-Type: application/json; charset=UTF-8
  Content-Transfer-Encoding: 8bit
  
  {"tags":["test"],"location_id":1,"post":{"content":"test"}}
  --d99ArGa2SaAsrXaGL_AdkNlmGn2wuflo5
  Content-Disposition: form-data; name="IMAGEDATA"; filename="testimage.jpg"
  Content-Type: image/jpeg
  Content-Transfer-Encoding: binary
  
  &lt;BINARY DATA?
  --d99ArGa2SaAsrXaGL_AdkNlmGn2wuflo5--
  </code></pre>
  
  <p>in the rails controller i'm creating the new post with this code:</p>
  
  <pre><code>@parsed_json = JSON(params[:POSTDATA])
  @post = @current_user.posts.new(@parsed_json["post"]) 
  </code></pre>
  
  <p>how do I make Paperclip save the attachment from the multipart form ?</p>
  
  <p>I can do it with something like this:</p>
  
  <pre><code>if params.has_key?(:IMAGEDATA)
      photo = params[:IMAGEDATA]
      photo.rewind
  
      @filename = "/tmp/tempfile"
      File.open(@filename, "wb") do |file|
        file.write(photo.read)
      end
  
      @post.photo = File.open(@filename)
    end
  </code></pre>
  
  <p>but it doesn't look like the best solution, also, the filename that is being passed in ther multipart request is not used.</p>