Merge pull request #4356 from sul-dlss/single-term

Use a special qf for single-term queries

app/models/search_builder.rb

@@ -12,6 +12,7 @@ class SearchBuilder < Blacklight::SearchBuilder
   self.default_processor_chain += [:database_prefix_search]
   self.default_processor_chain += [:modify_params_for_cjk, :modify_params_for_cjk_advanced]
   self.default_processor_chain += [:consolidate_home_page_params]
+  self.default_processor_chain += [:modify_single_term_qf]
 
   # Override range limit to only add parameters on search pages, not the home page
   def add_range_limit_params(*args)
@@ -34,6 +35,18 @@ def database_prefix_search(solr_params)
     solr_params[:fq] << "title_sort:/[#{blacklight_params[:prefix]}].*/"
   end
 
+  # Solr edismax does not apply phrase boosts to single-term matches. When we have a single term query,
+  # we can use a different set of query boosts to give better results.
+  def modify_single_term_qf(solr_params)
+    return unless Settings.search.use_single_term_query_fields
+    return unless blacklight_params && blacklight_params[:q].present? && solr_params[:qf].blank?
+
+    q_str = blacklight_params[:q]
+    return unless q_str.split.size == 1
+
+    solr_params[:qf] = '${qf_single_term}'
+  end
+
   private
 
   def page_location

config/settings.yml

@@ -98,6 +98,9 @@ dynamic_sitemap_solr_endpoint: 'select'
 browse_nearby:
   enabled: true
 
+search:
+  use_single_term_query_fields: false
+
 libraries:
   ARS:
     about_url: https://library.stanford.edu/libraries/archive-recorded-sound

spec/models/search_builder_spec.rb

@@ -34,6 +34,27 @@
     end
   end
 
+  describe 'single term query' do
+    before do
+      allow(Settings.search).to receive(:use_single_term_query_fields).and_return(true)
+    end
+
+    it "sets the single-term query fields" do
+      solr_params = search_builder.with(q: 'singleterm').to_hash
+      expect(solr_params[:qf]).to eq '${qf_single_term}'
+    end
+
+    it "leaves multi-term queries alone" do
+      solr_params = search_builder.with(q: 'multi term').to_hash
+      expect(solr_params[:qf]).to be_nil
+    end
+
+    it "leaves fielded search queries alone" do
+      solr_params = search_builder.with(q: 'multi term', search_field: 'search_title').to_hash
+      expect(solr_params[:qf]).to eq '${qf_title}'
+    end
+  end
+
   describe "advanced search" do
     let(:action_name) { 'advanced_search' }