Faceted Search with Sunspot - ruby-on-rails-3

Question

I'm trying to implement faceted search with Sunspot, but I must be doing something wrong.
class Product < ActiveRecord::Base
attr_accessible :category, :color, :condition, :item_no, :size
searchable do
text :color, :size
end
end
This is my product model, i want to have a menu on the side of the navigation which will allow to filter results by using category, color, condition etc.
In my controller i have:
def index
#search = Product.search do
fulltext params[:search]
facet :color
end
#products = #search.results
respond_to do |format|
format.html
format.json { render json: #products }
end
end
But i keep getting an error that says:
Sunspot::UnrecognizedFieldError
No field configured for Product with name 'color'
In the view I have:
<div id="facets">
<h3>Category</h3>
<ul>
<% for row in #search.facet(:color).rows %>
<li>
<% if params[:color].blank? %>
<%= link_to row.value, :color => row.value %> (<%= row.count %>)
<% else %>
<strong><%= row.value %></strong> (<%= link_to "remove", :color => nil %>)
<% end %>
</li>
<% end %>
</ul>
</div>
Can anyone point what to what I'm doing wrong?
Thanks a lot for the help!
Update:
This is a piece of the trace of the error.
sunspot (1.3.3) lib/sunspot/query/restriction.rb:245:in `to_solr_conditional'
sunspot (1.3.3) lib/sunspot/query/restriction.rb:92:in `to_positive_boolean_phrase'
sunspot (1.3.3) lib/sunspot/query/restriction.rb:72:in `to_boolean_phrase'
sunspot (1.3.3) lib/sunspot/query/filter.rb:11:in `to_filter_query'
sunspot (1.3.3) lib/sunspot/query/scope.rb:5:in `block in to_params'
sunspot (1.3.3) lib/sunspot/query/scope.rb:5:in `map'
sunspot (1.3.3) lib/sunspot/query/scope.rb:5:in `to_params'
sunspot (1.3.3) lib/sunspot/query/common_query.rb:51:in `block in to_params'
sunspot (1.3.3) lib/sunspot/query/common_query.rb:50:in `each'
sunspot (1.3.3) lib/sunspot/query/common_query.rb:50:in `to_params'
sunspot (1.3.3) lib/sunspot/search/abstract_search.rb:37:in `execute'
sunspot_rails (1.3.3) lib/sunspot/rails/searchable.rb:329:in `solr_execute_search'
sunspot_rails (1.3.3) lib/sunspot/rails/searchable.rb:153:in `solr_search'

Answer 1

Two things missing here. First, you need to include the color as a field, and second, the facet method tells sunspot (i.e., solr) to return all the facets that are present in the result set, but not to scope the query by that facet. So, you need something like:
searchable do
text :color, :size
string :color
end
#search = Product.search do
fulltext params[:search]
with(:color).all_of(params[:color]) unless params[:color].blank?
facet :color
end