how to use edit ajax link in controller.

Try this, Using the %{} make declaring a string over multiple lines easer and then you can also use direct #{} substitution for the variables which removes all the '+' and '"' characters.

@return_string += %{<tr bgcolor=white>                       <td>#{company.street_addr}</td>                       <td>#{company.city}</td>                       <td>#{company.state}</td>                       <td>#{company.pin}</td>                       <td width=10>#{company.branch}</td>                       <td width=10%>link_to_remote 'EDIT', :update => 'detail', :with => "company_id=#{company.id}", :url => { :action => 'edit_comp' }</td>                     </tr>}

David.