what @MarekLipka suggests is correct but defining your routes like this will take up all the single level namespace in your app i.e. "/anything" will route by default to posts#product
.
I recommended using some form of identifier to figure out which routes should go to posts#product
. What will work for you depends on why you want to do this. Couple of options are:
Use a short namespace:
scope '/pp' do
get ':id', to: 'posts#product
end
# "/pp/:id" routes to 'posts/product'
# pp is a random short name I picked, it could be anything
# link
<%= link_to sub_category.name, "pp/#{sub_category.slug}-#{sub_category.id}" %>
Use a constraint:
get ':id', to: 'posts#product`, constraints: { :id => /sub\-category/ }
# only id's with 'sub-cateogry' route to 'posts/product'
# link (assuming that sub_category.slug has 'sub-category' words in it)
<%= link_to sub_category.name, "#{sub_category.slug}-#{sub_category.id}" %>