Make #to_param aware about keys

Change-Id: Ie6eb5a680d040637578634f40a310a9d698fd94e
Reviewed-on: http://review.couchbase.org/21722
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>

lib/couchbase/model.rb

@@ -756,6 +756,13 @@ def to_key
       keys = [id || key]
       keys.empty? ? nil : keys
     end
+
+    def to_param
+      keys = to_key
+      if keys && !keys.empty?
+        keys.join("-")
+      end
+    end
   end
 
 end

test/test_model.rb

@@ -176,4 +176,9 @@ def test_to_key
     assert_equal ["the-key"], Post.new(:key => "the-key").to_key
   end
 
+  def test_to_param
+    assert_equal "the-id", Post.new(:id => "the-id").to_param
+    assert_equal "the-key", Post.new(:key => ["the", "key"]).to_param
+  end
+
 end