Add an indexed solr field for which exhibits an object appears in

app/models/concerns/spotlight/solr_document.rb

@@ -84,7 +84,9 @@ def sidecar(exhibit)
     end
 
     def to_solr
-      { self.class.unique_key.to_sym => id }.reverse_merge(sidecars.inject({}) { |acc, elem| acc.merge(elem.to_solr) }).merge(tags_to_solr)
+      { self.class.unique_key.to_sym => id }.reverse_merge(sidecars.inject({}) { |acc, elem| acc.merge(elem.to_solr) })
+                                            .merge(tags_to_solr)
+                                            .merge(exhibits_to_solr)
     end
 
     def make_public!(exhibit)
@@ -128,6 +130,14 @@ def tags_to_solr
       end
       h
     end
+
+    def exhibits_to_solr
+      slugs = sidecars.map(&:exhibit).map(&:slug)
+
+      {
+        "#{Spotlight::Engine.config.solr_fields.prefix}spotlight_exhibit_slugs#{Spotlight::Engine.config.solr_fields.string_suffix}" => slugs
+      }
+    end
   end
 end
 

spec/services/spotlight/solr_document_builder_spec.rb

@@ -35,6 +35,11 @@
         expect(result).to include "spotlight_exhibit_slug_#{resource_alt.exhibit.slug}_bsi"
       end
 
+      it 'has a field with both exhibit slugs listed' do
+        result = resource.document_builder.documents_to_index.first
+        expect(result).to include 'spotlight_exhibit_slugs_ssim' => match_array([resource.exhibit.slug, resource_alt.exhibit.slug])
+      end
+
       it 'creates a sidecar resource for the document' do
         resource.document_builder.documents_to_index.first