Avoid a crash reading an unknown ID on partitioned server (#2451)

* Avoid a crash reading an unknown ID on partitioned server. Fix #1953.

* Attempt 2 at fixing #1953

hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/5_4_0/1953-avoid-npe-performing-partitioned-read-for-unknown-id.yaml

@@ -0,0 +1,5 @@
+---
+type: fix
+issue: 1953
+title: "A crash was fixed when performing a FHIR read on a partitioned server, where the requested ID is not known. Thanks
+   to Umberto Cappellini for reporting!"

hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/dao/BaseHapiFhirResourceDao.java

@@ -1149,7 +1149,7 @@ public abstract class BaseHapiFhirResourceDao<T extends IBaseResource> extends B
 		BaseHasResource entity = myEntityManager.find(ResourceTable.class, pid.getIdAsLong());
 
 		// Verify that the resource is for the correct partition
-		if (!requestPartitionId.isAllPartitions()) {
+		if (entity != null && !requestPartitionId.isAllPartitions()) {
 			if (entity.getPartitionId() != null && entity.getPartitionId().getPartitionId() != null) {
 				if (!requestPartitionId.hasPartitionId(entity.getPartitionId().getPartitionId())) {
 					ourLog.debug("Performing a read for PartitionId={} but entity has partition: {}", requestPartitionId, entity.getPartitionId());

hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/dao/r4/PartitioningSqlR4Test.java

@@ -975,6 +975,58 @@ public class PartitioningSqlR4Test extends BasePartitioningR4Test {
 		}
 	}
 
+
+	@Test
+	public void testRead_PidId_UnknownResourceId() {
+		// Read in specific Partition
+		{
+			addReadPartition(1);
+			try {
+				myPatientDao.read(new IdType("Patient/1"), mySrd);
+				fail();
+			} catch (ResourceNotFoundException e) {
+				// expected
+			}
+		}
+
+		// Read in null Partition
+		{
+			addReadDefaultPartition();
+			try {
+				myPatientDao.read(new IdType("Patient/1"), mySrd);
+				fail();
+			} catch (ResourceNotFoundException e) {
+				// expected
+			}
+		}
+	}
+
+	@Test
+	public void testRead_PidId_ResourceIdOnlyExistsInDifferentPartition() {
+		IIdType id = createPatient(withPartition(2), withActiveTrue());
+		// Read in specific Partition
+		{
+			addReadPartition(1);
+			try {
+				myPatientDao.read(id, mySrd);
+				fail();
+			} catch (ResourceNotFoundException e) {
+				// expected
+			}
+		}
+
+		// Read in null Partition
+		{
+			addReadDefaultPartition();
+			try {
+				myPatientDao.read(id, mySrd);
+				fail();
+			} catch (ResourceNotFoundException e) {
+				// expected
+			}
+		}
+	}
+
 	@Test
 	public void testRead_ForcedId_SpecificPartition() {
 		IIdType patientIdNull = createPatient(withPutPartition(null), withActiveTrue(), withId("NULL"));