Merge pull request #173 from alphagov/did-you-mean

Implement `suggested_queries` in search response

app/models/result_set.rb

@@ -2,5 +2,5 @@
 class ResultSet
   include ActiveModel::Model
 
-  attr_accessor :results, :total, :start, :discovery_engine_attribution_token
+  attr_accessor :results, :total, :start, :discovery_engine_attribution_token, :suggested_queries
 end

app/services/discovery_engine/query/search.rb

@@ -16,10 +16,15 @@ def result_set
       Rails.logger.debug { "#{self.class.name}: Query: #{discovery_engine_params}" }
       response = client.search(discovery_engine_params).response
 
+      # Suggested queries always expects an array on the client side, even if there are no
+      # suggestions.
+      suggested_queries = suggest_correction? ? [response.corrected_query].compact_blank : []
+
       ResultSet.new(
         results: response.results.map { Result.from_stored_document(_1.document.struct_data.to_h) },
         total: response.total_size,
         start: offset,
+        suggested_queries:,
         discovery_engine_attribution_token: response.attribution_token,
       )
     end
@@ -75,6 +80,10 @@ def filter
       Filters.new(query_params).filter_expression
     end
 
+    def suggest_correction?
+      query_params[:suggest] == "spelling"
+    end
+
     def serving_config
       Rails.configuration.discovery_engine_serving_config
     end

spec/requests/search_request_spec.rb

@@ -1,6 +1,6 @@
 RSpec.describe "Making a search request" do
   let(:search_service) { instance_double(DiscoveryEngine::Query::Search, result_set:) }
-  let(:result_set) { ResultSet.new(results:, total: 42, start: 21) }
+  let(:result_set) { ResultSet.new(results:, total: 42, start: 21, suggested_queries: %w[foo]) }
   let(:results) { [Result.new(content_id: "123"), Result.new(content_id: "456")] }
 
   before do
@@ -19,6 +19,7 @@
         ],
         "total" => 42,
         "start" => 21,
+        "suggested_queries" => %w[foo],
       })
     end
 

spec/services/discovery_engine/query/search_spec.rb

@@ -34,13 +34,21 @@
       let(:query_params) { { q: "garden centres" } }
 
       let(:search_return_value) { double(response: search_response) }
-      let(:search_response) { double(total_size: 42, attribution_token: "footobar", results:) }
+      let(:search_response) do
+        double(
+          total_size: 42,
+          attribution_token: "footobar",
+          results:,
+          corrected_query:,
+        )
+      end
       let(:results) do
         [
           double(document: double(struct_data: { title: "Louth Garden Centre" })),
           double(document: double(struct_data: { title: "Cleethorpes Garden Centre" })),
         ]
       end
+      let(:corrected_query) { nil }
 
       it "calls the client with the expected parameters" do
         expect(client).to have_received(:search).with(
@@ -122,6 +130,26 @@
         end
       end
 
+      context "when searching for a query where the client returns a corrected query" do
+        let(:corrected_query) { "graden crentres" }
+
+        context "and the suggest parameter is 'spelling'" do
+          let(:query_params) { { q: "garden centres", suggest: "spelling" } }
+
+          it "returns the corrected query in the result set" do
+            expect(result_set.suggested_queries).to eq([corrected_query])
+          end
+        end
+
+        context "and the suggest parameter is not set" do
+          let(:query_params) { { q: "garden centres" } }
+
+          it "does not return a corrected query in the result set" do
+            expect(result_set.suggested_queries).to be_empty
+          end
+        end
+      end
+
       context "when searching for a query that has a single best bets defined" do
         # see test section in YAML config
         let(:query_params) { { q: "i want to test a single best bet" } }