ruby on rails - undefined method `name' for nil:NilClass -

i have problem on te line

<td><%= h box.manufacturer.name %></td> 

of

<% @boxes.each |box| %>   <tr>   <td><%= h box.manufacturer.name %></td>   <td><%= h box.model %></td>   <td><%= link_to 'mostrar', :action => 'show', :id => box %></td>   <td><%= link_to 'editar', :action => 'edit', :id => box  %></td>   <td><%= button_to 'eliminar', { :action => 'destroy', :id => box },   :confirm => "are sure want delete box #{box.model}?" %></td> 

manufacturers table field called name,its supposed object manufacturer has member called name ,isn it?

it's quite clear 1 of box records doesn't have associated manufacturer. if it's acceptable, can use object#try method, this:

<%= box.manufacturer.try(:name) %> 

if it's not, should think of adding proper validation box model:

validates_presence_of :manufacturer 

i didn't use h helper because in rails >= 3.0 (which use) untrusted content escaped automatically.