Add possible overriding pattern to remove genreform from subjects, use for formats

config/traject/ead2_config.rb

@@ -1,5 +1,9 @@
 # frozen_string_literal: true
 
+def remove_to_field_def(field_name)
+  instance_variable_get(:@index_steps).reject! { |f| f.instance_variable_get(:@field_name) == field_name }
+end
+
 # Load the arclight gem's default EAD2 traject configuration first.
 # All additions and modifications below are kept separate from the upstream defaults.
 load_config_file Arclight::Engine.root.join("lib/arclight/traject/ead2_config.rb").to_s
@@ -8,3 +12,24 @@
 # Boxrunner-specific additions / overrides
 # ==========================================
 
+# Utilize genreform for Formats facet
+
+remove_to_field_def "access_subjects_ssim"
+remove_to_field_def "access_subjects_ssm"
+
+to_field "access_subjects_ssim", extract_xpath("/ead/archdesc/controlaccess", to_text: false) do |_record, accumulator|
+  accumulator.map! do |element|
+    %w[subject function occupation].map do |selector|
+      element.xpath(".//#{selector}").map(&:text)
+    end
+  end.flatten!
+end
+
+to_field "access_subjects_ssm" do |_record, accumulator, context|
+  accumulator.concat Array.wrap(context.output_hash["access_subjects_ssim"])
+end
+
+to_field "formats_ssim", extract_xpath("/ead/archdesc/controlaccess/genreform|/ead/archdesc/controlaccess/controlaccess/genreform")
+to_field "formats_ssm" do |_record, accumulator, context|
+  accumulator.concat Array.wrap(context.output_hash["formats_ssim"])
+end

spec/config/traject/ead2_config_spec.rb

@@ -133,14 +133,21 @@
     it "maps access_subjects_ssim from controlaccess subjects" do
       expect(result["access_subjects_ssim"]).to include "Women in science."
       expect(result["access_subjects_ssim"]).to include "Women engineers."
+      expect(result["access_subjects_ssim"]).to_not include "Digital file formats."
     end
 
     it "maps access_subjects_ssm from access_subjects_ssim" do
       expect(result["access_subjects_ssm"]).to eq result["access_subjects_ssim"]
     end
+  end
+
+  describe "formats" do
+    it "maps genreform to formats_ssim" do
+      expect(result["formats_ssim"]).to include "Digital file formats."
+    end
 
-    it "maps genreform_ssim from controlaccess" do
-      expect(result["genreform_ssim"]).to include "Photographs."
+    it "maps formats_ssim to formats_ssm" do
+      expect(result["formats_ssim"]).to eq result["formats_ssm"]
     end
   end