rails 3 undefined method `+' for nil:NilClass -

i making sorting table in rails , getting error. index.html.erb

<table>     <tr>       <th><%= sortable "name" %></th>     <th><%= sortable "city" %></th>     <th><%= sortable "country" %></th>     <th><%= sortable "street_address" %></th>     <th><%= sortable "sector" %></th>     <th><%= sortable "telephone" %></th>     <th><%= sortable "fax" %></th>   </tr>      <% company in @companies %>     <tr>       <td><%= company.name %></td>     <td><%= company.city %></td>     <td><%= company.country %></td>     <td><%= company.street_address %></td>     <td><%= company.sector %></td>     <td><%= company.telephone %></td>     <td><%= company.fax %></td>   </tr>   <% end %> </table> 

this companies_controller

def index   @companies = company.order(params[:sort] + ' ' + params[:direction]) end 

this application_helper

def sortable(column, title = nil)       title ||= column.titleize       direction = (column == params[:sort] && params[:direction] == "asc") ? "desc" : "asc"       link_to title, :sort => column, :direction => direction   end 

and error is:

nomethoderror in companiescontroller#index  undefined method `+' nil:nilclass app/controllers/companies_controller.rb:21:in `index' 

what problem , how can fix it?

your params[:sort] returns nil.

you can fix example checking params:

@companies = company.scoped if params[:sort].present? && params[:direction].present?   @companies = @companies.order(params[:sort] + ' ' + params[:direction]) end