select product option

gistfile1.rb

my route
get 'products/:id(/:color_id(/:size_id))' => 'products#show', :as => "select_product_option"

in my product_group model

def size size_id
  return nil unless size_id
  product_sizes.find(size_id)

end

def color color_id
  return nil unless color_id
  product_colors.find(color_id)
end

def product_by_color_and_size color, size
  return nil unless color
  return nil unless size
  products.find_by_product_color_id_and_product_size_id(color.id,size.id)
end


in my controller:

def show
  @product_group = ProductGroup.find(params[:id])
  @color = @product_group.color(params[:color_id])
  @size = @product_group.size(params[:size_id])
  @product = @product_group.product_by_color_and_size(@color, @size)
end

now in my view I need two selects like this:

select color
<ul>
  <li>
    blue    
  </li>
  <li>
    braun
  </li>
</ul>

select size

<ul>
  <li>
    M    
  </li>
  <li>
    L
  </li>
</ul>

Whats the best way to select/choose size and color to find the product?

If there's no color, show a select with all possible colors. On select navigate the page to the value of the select option using JS.

If you have a @color, also show the size options that again navigates to the select option value.

The JS using jQuery could look something like this:

$("#colors-select").change(function() {
    location.href = "/products/5/" + $("#colors-select").val();
});

you should be using spree or at least checking it's sources