rails_admin.rb

RailsAdmin.config do |config|
	config.actions do
		dashboard
		index
    new
    show
    edit
    delete

		collection :upload_renewals do
			register_instance_option :link_icon do
				'icon-upload'
			end

			register_instance_option :visible? do
				bindings[:abstract_model].to_s == "Renewal"
			end

			register_instance_option :http_methods do
			    [:get, :post]
			end

			register_instance_option :pjax? do
    		false
      end


			register_instance_option :controller do
				Proc.new do
					if params.has_key?(:import_file)
						doc = SimpleXlsxReader.open(params[:import_file].tempfile)
        
    					main_sheet = doc.sheets.first
    					count = 0
    					main_sheet.rows[1..main_sheet.rows.length].each do |row|      
    						count += 1
    					end
    					redirect_to back_or_index, notice: "#{count} Rows imported"
					end
				end
			end
		end
	end
end

upload_renewals.html.haml

%form.form-horizontal.denser{:method => "POST", :enctype => "multipart/form-data" }
  %input{:name => "authenticity_token", :type => "hidden", :value => form_authenticity_token}
  %fieldset
    .control-group
      %label.control-label{:for => "import_file"}
        Import File
      .controls
        %input{:type => "file", :name => "import_file"} 
        %p.help-block
          Select the .xls file to be imported
  .form-actions
    %button.btn.btn-primary{:type => "submit"}
      Upload