Index lc_facet field (#2547)

* Index lc_facet field

* Rubocop

* Use dig to reduce nested if statements

Co-authored-by: Max Kadel <[email protected]>

* Revert "Use dig to reduce nested if statements"

This reverts commit eaa24e2.

---------

Co-authored-by: Ryan Laddusaw <[email protected]>
Co-authored-by: Max Kadel <[email protected]>

marc_to_solr/lib/traject_config.rb

@@ -972,6 +972,17 @@
   end
 end
 
+to_field 'lc_facet' do |record, accumulator|
+  if record['050']
+    if record['050']['a']
+      first_letter = record['050']['a'].lstrip.slice(0, 1)
+      letters = /([[:alpha:]])*/.match(record['050']['a'])[0]
+      accumulator << Traject::TranslationMap.new("callnumber_map")[first_letter]
+      accumulator << "#{Traject::TranslationMap.new('callnumber_map')[first_letter]}:#{Traject::TranslationMap.new('callnumber_map')[letters]}"
+    end
+  end
+end
+
 to_field 'sudoc_facet' do |record, accumulator|
   MarcExtractor.cached('086|0 |a').collect_matching_lines(record) do |field, spec, extractor|
     letters = /([[:alpha:]])*/.match(extractor.collect_subfields(field, spec).first)[0] if /([[:alpha:]])*/.match?(extractor.collect_subfields(field, spec).first)

spec/marc_to_solr/lib/config_spec.rb

@@ -977,6 +977,21 @@ def fixture_record(fixture_name, indexer: @indexer)
       end
     end
 
+    describe 'lc_facet' do
+      it 'includes a field with data for the classification facet' do
+        lc_facet = @sample40['lc_facet']
+        expect(lc_facet).to match_array(['R - Medicine', 'R - Medicine:RA - Public Aspects of Medicine'])
+      end
+      it 'handles cases where the call number is a single letter' do
+        lc_facet = @sample44['lc_facet']
+        expect(lc_facet).to match_array(['Z - Bibliography, Library Science, Information Resources', 'Z - Bibliography, Library Science, Information Resources:Z - Bibliography, Library Science, Information Resources'])
+      end
+      it 'handles cases where there is no call number' do
+        lc_facet = @record_no_call_number['lc_facet']
+        expect(lc_facet).to be_nil
+      end
+    end
+
     describe 'series 490 dedup, non-filing' do
       let(:s490) { { "490" => { "ind1" => "", "ind2" => " ", "subfields" => [{ "a" => "Series title" }] } } }
       let(:s830) { { "830" => { "ind1" => "", "ind2" => " ", "subfields" => [{ "a" => "Series title." }] } } }