Support per_page parameter

app/graphql/types/query_type.rb

@@ -54,6 +54,8 @@ def record_id(id:, index:)
       argument :title, String, required: false, default_value: nil, description: 'Search by title'
       argument :from, String, required: false, default_value: '0',
                               description: 'Search result number to begin with (the first result is 0)'
+      argument :per_page, Integer, required: false, default_value: 20,
+                                   description: 'Number of results per page. Defaults to 20.'
       argument :fulltext, Boolean, required: false, default_value: false,
                                    description: 'Include fulltext field in search? Defaults to false.'
       argument :index, String, required: false, default_value: nil,
@@ -101,9 +103,9 @@ def record_id(id:, index:)
     end
 
     def search(searchterm:, citation:, contributors:, funding_information:, geodistance:, geobox:, identifiers:,
-               locations:, subjects:, title:, index:, source:, from:, boolean_type:, fulltext:, **filters)
+               locations:, subjects:, title:, index:, source:, from:, boolean_type:, fulltext:, per_page: 20, **filters)
       query = construct_query(searchterm, citation, contributors, funding_information, geodistance, geobox, identifiers,
-                              locations, subjects, title, source, boolean_type, filters)
+                              locations, subjects, title, source, boolean_type, filters, per_page)
 
       results = Opensearch.new.search(from, query, Timdex::OSClient, highlight_requested?, index, fulltext)
 
@@ -133,7 +135,7 @@ def inject_hits_fields_into_source(hits)
     end
 
     def construct_query(searchterm, citation, contributors, funding_information, geodistance, geobox, identifiers,
-                        locations, subjects, title, source, boolean_type, filters)
+                        locations, subjects, title, source, boolean_type, filters, per_page)
       query = {}
       query[:q] = searchterm
       query[:boolean_type] = boolean_type
@@ -144,6 +146,7 @@ def construct_query(searchterm, citation, contributors, funding_information, geo
       query[:geobox] = geobox
       query[:identifiers] = identifiers
       query[:locations] = locations
+      query[:per_page] = per_page
       query[:subjects] = subjects
       query[:title] = title
       query[:access_to_files_filter] = filters[:access_to_files_filter]

app/models/opensearch.rb

@@ -2,7 +2,7 @@
 # rubocop:disable Metrics/MethodLength
 class Opensearch
   SIZE = 20
-  MAX_PAGE = 200
+  MAX_SIZE = 200
 
   def search(from, params, client, highlight = false, index = nil, fulltext = false)
     @params = params
@@ -24,9 +24,18 @@ def default_index
 
   # Construct the json query to send to elasticsearch
   def build_query(from)
+    # allow overriding the OpenSearch `size` via params (per_page), capped by MAX_PAGE
+    calculate_size = if @params && @params[:per_page]
+                       per_page = @params[:per_page].to_i
+                       per_page = SIZE if per_page <= 0
+                       [per_page, MAX_SIZE].min
+                     else
+                       SIZE
+                     end
+
     query_hash = {
       from:,
-      size: SIZE,
+      size: calculate_size,
       query:,
       aggregations: Aggregations.all,
       sort:

test/controllers/graphql_controller_test.rb

@@ -937,4 +937,23 @@ class GraphqlControllerTest < ActionDispatch::IntegrationTest
       end
     end
   end
+
+  test 'graphql search respects perPage argument' do
+    VCR.use_cassette('opensearch_init') do
+      VCR.use_cassette('graphql_search_per_page_5', match_requests_on: [:method, :uri]) do
+        post '/graphql', params: { query: '{
+                                    search(perPage:5) {
+                                      hits
+                                      records {
+                                        title
+                                      }
+                                    }
+                                  }' }
+        assert_equal(200, response.status)
+        json = JSON.parse(response.body)
+        assert_equal(5, json['data']['search']['records'].count)
+        assert_equal(100, json['data']['search']['hits'])
+      end
+    end
+  end
 end

test/models/opensearch_test.rb

@@ -359,4 +359,32 @@ class OpensearchTest < ActiveSupport::TestCase
       os.query.to_json.include?('{"locations.geoshape":{"top":"42.886","bottom":"41.239","left":"-69.507","right":"-73.928"}}')
     )
   end
+
+  test 'build_query uses default size' do
+    os = Opensearch.new
+    os.instance_variable_set(:@params, {})
+    json = JSON.parse(os.build_query(0))
+    assert_equal Opensearch::SIZE, json['size']
+  end
+
+  test 'build_query respects per_page' do
+    os = Opensearch.new
+    os.instance_variable_set(:@params, { per_page: 5 })
+    json = JSON.parse(os.build_query(0))
+    assert_equal 5, json['size']
+  end
+
+  test 'build_query falls back for nonpositive per_page' do
+    os = Opensearch.new
+    os.instance_variable_set(:@params, { per_page: 0 })
+    json = JSON.parse(os.build_query(0))
+    assert_equal Opensearch::SIZE, json['size']
+  end
+
+  test 'build_query caps per_page at MAX_SIZE' do
+    os = Opensearch.new
+    os.instance_variable_set(:@params, { per_page: Opensearch::MAX_SIZE + 100 })
+    json = JSON.parse(os.build_query(0))
+    assert_equal Opensearch::MAX_SIZE, json['size']
+  end
 end