IndexedSearchParamExtractor regression returned wrong number of links pre-persistence (#4341)

* fixed the issue

* change log

* fix regression

Co-authored-by: Ken Stevens <ken@smilecdr.com>

hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_4_0/4341-indexedsearchparamextractor-links.yaml

@@ -0,0 +1,6 @@
+---
+type: fix
+issue: 4341
+title: "Fixes a regression where IndexedSearchParamExtractor returns too few links when extracting search parameters from
+a resource that hasn't persisted yet.  E.g. when a create interceptor needs to extract search parameters from the resource
+before it is persisted."

hapi-fhir-jpaserver-model/src/main/java/ca/uhn/fhir/jpa/model/entity/ResourceLink.java

@@ -143,7 +143,13 @@ public class ResourceLink extends BaseResourceIndex {
 		b.append(myTargetResourceUrl, obj.myTargetResourceUrl);
 		b.append(myTargetResourceType, obj.myTargetResourceType);
 		b.append(myTargetResourceVersion, obj.myTargetResourceVersion);
+		// In cases where we are extracting links from a resource that has not yet been persisted, the target resource pid
+		// will be null so we use the target resource id to differentiate instead
+		if (getTargetResourcePid() == null) {
+			b.append(getTargetResourceId(), obj.getTargetResourceId());
+		} else {
 			b.append(getTargetResourcePid(), obj.getTargetResourcePid());
+		}
 		return b.isEquals();
 	}
 
@@ -256,7 +262,14 @@ public class ResourceLink extends BaseResourceIndex {
 		b.append(mySourceResource);
 		b.append(myTargetResourceUrl);
 		b.append(myTargetResourceVersion);
+
+		// In cases where we are extracting links from a resource that has not yet been persisted, the target resource pid
+		// will be null so we use the target resource id to differentiate instead
+		if (getTargetResourcePid() == null) {
+			b.append(getTargetResourceId());
+		} else {
 			b.append(getTargetResourcePid());
+		}
 		return b.toHashCode();
 	}
 

hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/searchparam/matcher/IndexedSearchParamExtractorTest.java

@@ -0,0 +1,41 @@
+package ca.uhn.fhir.jpa.searchparam.matcher;
+
+import ca.uhn.fhir.jpa.searchparam.extractor.ResourceIndexedSearchParams;
+import ca.uhn.fhir.jpa.test.BaseJpaR4Test;
+import org.hl7.fhir.r4.model.Appointment;
+import org.hl7.fhir.r4.model.Encounter;
+import org.hl7.fhir.r4.model.Reference;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.transaction.PlatformTransactionManager;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class IndexedSearchParamExtractorTest extends BaseJpaR4Test {
+	@Autowired
+	PlatformTransactionManager myPlatformTransactionManager;
+
+	// SUT: System Under Test
+	@Autowired
+	IndexedSearchParamExtractor mySrv;
+
+	@Override
+	protected PlatformTransactionManager getTxManager() {
+		return myPlatformTransactionManager;
+	}
+
+	@Test
+	public void extractIndexedSearchParams_twoReferences_twoLinks() {
+		Encounter encounter = new Encounter();
+		Appointment appt1 = new Appointment();
+		appt1.setId("Appointment/appt1");
+		encounter.addAppointment(new Reference(appt1));
+		Appointment appt2 = new Appointment();
+		appt2.setId("Appointment/appt2");
+		encounter.addAppointment(new Reference(appt2));
+
+		ResourceIndexedSearchParams result = mySrv.extractIndexedSearchParams(encounter, mySrd);
+		// red-green before the fix, the size was 1
+		assertEquals(2, result.myLinks.size());
+	}
+}