Uploading file yields 406 (Not Acceptable) error - ruby

Question

I am trying to upload a file using sample code. I am not getting any compilation errors but a 406 Not Acceptable error message. What does this mean?
POST request:
Started POST "/files/upload" for 10.15.24.38 at 2012-06-22 21:18:11 -0400
Processing by FilesController#upload as HTML
Parameters: {"utf8"=>"â", "authenticity_token"=>"wfpBi3Y8KgmqitXrh4fZ3xfun73mWOfXiTQ+J7bdfWU=", "user_id"=>"231",
"button"=>"", "upload"=>{"datafile"=>"ws_1920x1080.jpg"}}
View:
<%= form_tag files_upload_path, :remote => true, :method => :post, :multipart => true do %>
#The form has some other values too. I am keeping it short here.
<p>
<label for="upload_file">Select File</label> :
<%= file_field 'upload', 'datafile' %>
</p>
<% end %>
Controller:
def upload
#The controller has some other values too, that are not related to file upload.
if params[:datafile]
uploaded_io = params[:upload][:datafile]
File.open(Rails.root.join('public', 'uploads', uploaded_io.original_filename), 'w') do |file|
file.write(uploaded_io.read)
end
end
if params[:user_id]
#do some extra stuff
end
respond_to do |format|
format.js
end
end
Error:
Completed 406 Not Acceptable in 2736ms (ActiveRecord: 3.2ms)

Answer 1

There isn't enough information to provide the answer but you're clearly missing :multipart => true in our form_for call as in:
<%= form_for #upload, :multipart => true do |f| %>
Your form code here
<% end %>
And the not acceptable error happens because you're asking for HTML rendering but there is probably not a respond_to piece answering to HTML.

Answer 2

You are not allowed (in direct way) to upload files through remote request. Take a look here: How can I upload files asynchronously?

Answer 3

I guess you cant upload a file using ajax just by specifying remote => true you need some sort of plugin or something like it to do it like
remotipart , plupload , uploadify or something like it .
so if you are not using any plugin then even if you specify remote => true the form would be sent as normal HTML request instead of XMLHttpRequest
Now since in your controller you have removed
format.html part as you are assuming that it would be an ajax request but in reality it is not (HTML request)
becoz Rails cannot find the appropriate format to respond back it is reporting 406 Not Acceptable
Do your self a favor log the request.xhr? method in your controller.
something like
logger.info "******************** #{request.xhr?} *********************"
If request.xhr? return nil that specify that request is not an ajax request