Trap for a nil pointer and give a helpful message

sul-dlss · Oct 7, 2019 · 1e70e14 · 1e70e14
1 parent 93c01d7
commit 1e70e14
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diff --git a/app/services/public_xml_service.rb b/app/services/public_xml_service.rb
@@ -104,6 +104,13 @@ def add_data_from_src(external_file)
     # locate and extract the resourceId/fileId elements
     doc = src_item.contentMetadata.ng_xml
     src_resource = doc.at_xpath("//resource[@id=\"#{src_resource_id}\"]")
+
+    unless src_resource
+      raise Dor::DataError, "The contentMetadata of #{object.pid} has an exernalFile "\
+        "reference to #{src_druid}, #{src_resource_id}, but #{src_druid} doesn't have " \
+        "a matching resource node in it's contentMetadata"
+    end
+
     src_file = src_resource.at_xpath("file[@id=\"#{src_file_id}\"]")
     raise Dor::DataError, "Unable to find a file node with id=\"#{src_file_id}\" (child of #{object.pid})" unless src_file
 

diff --git a/spec/services/public_xml_service_spec.rb b/spec/services/public_xml_service_spec.rb
@@ -216,6 +216,36 @@
         expect(ng_xml.at_xpath('/publicObject/thumb').to_xml).to be_equivalent_to('<thumb>jw923xn5254/2542B.jp2</thumb>')
       end
 
+      context 'when the referenced object does not have the referenced resource' do
+        let(:cover_item) { instance_double(Dor::Item, pid: 'druid:cg767mn6478', contentMetadata: contentMetadata) }
+        let(:contentMetadata) { instance_double(Dor::ContentMetadataDS, ng_xml: Nokogiri::XML(cm_xml)) }
+        let(:cm_xml) do
+          <<-EOXML
+          <contentMetadata objectId="cg767mn6478" type="map">
+          </contentMetadata>
+          EOXML
+        end
+
+        before do
+          item.contentMetadata.content = <<-EOXML
+          <contentMetadata objectId="hj097bm8879" type="map">
+            <resource id="hj097bm8879_1" sequence="1" type="image">
+              <externalFile fileId="2542A.jp2" objectId="druid:cg767mn6478" resourceId="cg767mn6478_1" />
+              <relationship objectId="druid:cg767mn6478" type="alsoAvailableAs"/>
+            </resource>
+          </contentMetadata>
+          EOXML
+
+          allow(Dor).to receive(:find).with(cover_item.pid).and_return(cover_item)
+        end
+
+        it 'raises an error' do
+          expect { xml }.to raise_error(Dor::DataError, 'The contentMetadata of druid:ab123cd4567 has an exernalFile ' \
+            "reference to druid:cg767mn6478, cg767mn6478_1, but druid:cg767mn6478 doesn't have " \
+            "a matching resource node in it's contentMetadata")
+        end
+      end
+
       context 'when the referenced object does not have the referenced image' do
         let(:cover_item) { instance_double(Dor::Item, pid: 'druid:cg767mn6478', contentMetadata: contentMetadata) }
         let(:contentMetadata) { instance_double(Dor::ContentMetadataDS, ng_xml: Nokogiri::XML(cm_xml)) }