Monkey patch CouchRest for supporting redis caching

gistfile1.rb

class CouchRest::Database
    alias :old_save_doc :save_doc
    alias :old_delete_doc :delete_doc
    attr_writer :rcache
    
    # Automatically add the created_at and updated_at time fields to the 
    # document and also save it back to redis with a ttl.
    def save_doc doc, bulk = false, batch = false
        doc['created_at'] ||= Time.now
        doc['updated_at'] = Time.now
        res = old_save_doc doc, bulk, batch
        rcache.set doc['_id'], doc
        return res
    end
    
    # Purge the key from redis after a successful delete
    def delete_doc doc
        res = old_delete_doc doc
        rcache.del doc['_id']
        return res
    end
    
    # Fetch from redis first and if not, go to CouchDB. 
    def cache_get id
        rcache.get id do
            self.get id rescue nil
        end
    end
end