Import DFC graphs with multiple objects

lib/data_food_consortium/connector/importer.rb

@@ -20,11 +20,16 @@ module DataFoodConsortium
       end
 
       def import(json_string)
+        @subjects = {}
+
         graph = parse_rdf(json_string)
-        head, *tail = graph.to_a
-        subject = build_subject(head)
-        apply_statements(subject, tail)
-        subject
+        apply_statements(graph)
+
+        if @subjects.size > 1
+          @subjects.values
+        else
+          @subjects.values.first
+        end
       end
 
       private
@@ -42,13 +47,15 @@ module DataFoodConsortium
         clazz.new(id)
       end
 
-      def apply_statements(subject, statements)
+      def apply_statements(statements)
         statements.each do |statement|
-          apply_statement(subject, statement)
+          apply_statement(statement)
         end
       end
 
-      def apply_statement(subject, statement)
+      def apply_statement(statement)
+        subject = subject_of(statement)
+
         return unless subject.hasSemanticProperty?(statement.predicate.value)
 
         prop_name = statement.predicate.fragment
@@ -59,6 +66,10 @@ module DataFoodConsortium
         value = statement.object.object
         subject.public_send(setter_name, value)
       end
+
+      def subject_of(statement)
+        @subjects[statement.subject] ||= build_subject(statement)
+      end
     end
   end
 end

spec/lib/data_food_consortium/connector/importer_spec.rb

@@ -5,6 +5,12 @@ require Rails.root.join('lib/data_food_consortium/connector/connector')
 
 describe DataFoodConsortium::Connector::Importer, vcr: true do
   let(:connector) { DataFoodConsortium::Connector::Connector.instance }
+  let(:catalog_item) do
+    DataFoodConsortium::Connector::CatalogItem.new(
+      "https://example.net/tomatoItem",
+      product:,
+    )
+  end
   let(:product) do
     DataFoodConsortium::Connector::SuppliedProduct.new(
       "https://example.net/tomato",
@@ -25,6 +31,22 @@ describe DataFoodConsortium::Connector::Importer, vcr: true do
     expect(result.totalTheoreticalStock).to eq 3
   end
 
+  it "imports a graph with multiple objects" do
+    result = import(catalog_item, product)
+
+    expect(result).to be_a Array
+    expect(result.size).to eq 2
+
+    item, tomato = result
+
+    expect(item.class).to eq catalog_item.class
+    expect(item.semanticType).to eq catalog_item.semanticType
+    expect(item.semanticId).to eq "https://example.net/tomatoItem"
+    expect(tomato.name).to eq "Tomato"
+    expect(tomato.description).to eq "Awesome tomato"
+    expect(tomato.totalTheoreticalStock).to eq 3
+  end
+
   def import(*args)
     json = connector.export(*args)
     connector.import(json)