SPARQL gem monkey-patches Hash#deep_dup and breaks Blacklight's expec…

…ted contract with Rails

lib/hyrax/engine.rb

@@ -80,6 +80,10 @@ class Engine < ::Rails::Engine
         message += "It is UNEXPECTED if you are booting up a Hyrax powered application via `rails server'"
         Rails.logger.info(message)
       end
+
+      # Force CatalogController to use our SearchState class, which has an important
+      # work-around for some highly suspect SPARQL-gem monkeypatching.
+      CatalogController.search_state_class = Hyrax::SearchState if CatalogController.search_state_class == Blacklight::SearchState
     end
 
     initializer 'requires' do

lib/hyrax/search_state.rb

@@ -9,5 +9,14 @@ def url_for_document(doc, _options = {})
       return [hyrax, doc] if doc.collection?
       [main_app, doc]
     end
+
+    # The SPARQL gem stomps on the Rails definition of deep_dup and gives us a Hash instead of
+    # a HashWithIndifferentAccess. This is an ugly workaround to get the right contract with
+    # the upstream class.
+    # https://github.com/ruby-rdf/sparql/blob/develop/lib/sparql/algebra/extensions.rb#L238-L244
+    def to_hash
+      super.with_indifferent_access
+    end
+    alias to_h to_hash
   end
 end