Rails: Exporting to CSV failing

I am attempting to export my data to a CSV file. This is my model:

def self.generate_csv(ids)
    CSV.generate({:col_sep => "\t"}) do |csv|
      csv << ['topfind terminus id','position','sequence','protein (uniprot ac)','topfind evidence ids']
      ids.each do |id|
        n = Nterm.find(id)       
        csv << [n.externalid,n.pos,n.protein.sequence[n.pos-1..n.pos+9],n.protein.ac,n.evidences.collect{|e| e.externalid}.join(':')]
      end
    end  
  end 

And this is the controller for this model that calls this method:

  def show
     puts "id search: [#{params[:id]}]" 
     @output = Nterm.generate_csv(params[:id])
     respond_to do |format|
       format.html
       format.csv { send_data @output.as_csv }
     end
     p @output
  end

And this is my view:

<%= link_to "Export to CSV", {:method=> "show", :id => @nterm.map {|i| i.id }} %>

I'm not quite sure what to put on my show view in this case. How do I produce a CSV?

Change your view as following, use your route path for view action, instead of id, pass ids because its collection of ids not single id.

<%= link_to "Export to CSV", your_route_path(:format => :csv, :ids => @nterm.map {|i| i.id }}) %>

And slide changes need to your action as following, for receive ids

def show
 @output = Nterm.generate_csv(params[:ids])
 #your codes goes here 
end