[karmi#446] Changed, that arbitrary objects passed in the :as mappi…

…ng option are indexed

Previously, objects other then `String` or `Proc` were silently discarded
when evaluating the `:as` mapping option.

With this change, you may pass whatever object you like in the `:as` mapping option:

    class MyModel
        include Some::ORM
        include Tire::Model::Search

        mapping do
          indexes :field, :type => 'string', :analyzer => 'keyword', :as => SomeOtherObject.whatever
        end
      end
    end

    class MyModel
        include Some::ORM
        include Tire::Model::Search

        mapping do
          indexes :field, :type => 'string', :analyzer => 'keyword', :as => [1, 2, 3]
        end
      end
    end

This commit is a conceptual opposite of karmi/retire@0ccee42. Until karmi#446 is decided,
this change brings some consistency to the behaviour.

lib/tire/model/search.rb

@@ -154,7 +154,7 @@ def update_index
         # declared in the mapping are serialized.
         #
         # For properties declared with the `:as` option, the passed String or Proc
-        # is evaluated in the instance context.
+        # is evaluated in the instance context. Other objects are indexed "as is".
         #
         def to_indexed_json
           if instance.class.tire.mapping.empty?
@@ -172,7 +172,9 @@ def to_indexed_json
                   hash[key] = instance.instance_eval(options[:as])
                 when Proc
                   hash[key] = instance.instance_eval(&options[:as])
-              end
+                else
+                  hash[key] = options[:as]
+              end if options[:as]
             end
 
             hash.to_json

test/unit/model_search_test.rb

@@ -620,7 +620,7 @@ def method_missing(name, *args, &block)
 
           end
 
-          should "serialize mapped properties when mapping procs are set" do
+          should "evaluate :as mapping options passed as strings or procs" do
             class ::ModelWithMappingProcs
               extend  ActiveModel::Naming
               extend  ActiveModel::Callbacks
@@ -656,6 +656,28 @@ def method_missing(name, *args, &block)
             assert_equal 3, document['three']
           end
 
+          should "index :as mapping options passed as arbitrary objects" do
+            class ::ModelWithMappingOptionAsObject
+              extend  ActiveModel::Naming
+              extend  ActiveModel::Callbacks
+              include ActiveModel::Serialization
+              include Tire::Model::Search
+
+              mapping do
+                indexes :one,   :as => [1, 2, 3]
+              end
+
+              attr_reader :attributes
+
+              def initialize(attributes = {}); @attributes = attributes; end
+            end
+
+            model    = ::ModelWithMappingOptionAsObject.new
+            document = MultiJson.decode(model.to_indexed_json)
+
+            assert_equal [1, 2, 3], document['one']
+          end
+
         end
 
         context "with percolation" do