From 1faf77dcc8394929377fdf7da378a005a8e2b495 Mon Sep 17 00:00:00 2001
From: Luke deGruchy <luke.degruchy@smilecdr.com>
Date: Thu, 30 Mar 2023 12:51:17 -0400
Subject: [PATCH] Fix error message for bad $mdm-link-history input and handle
 comma-delimited input (#4701)

* Fix error message for bad $mdm-link-history input and handle comma-delimited input.

* Code review feedback:  filter out null objects in the stream.
---
 ...ror-messge-and-comma-delimited-inputs.yaml |  5 +++++
 .../fhir/mdm/provider/BaseMdmProvider.java    | 20 ++++++++++++++-----
 .../MdmLinkHistoryProviderDstu3Plus.java      |  4 ++--
 3 files changed, 22 insertions(+), 7 deletions(-)
 create mode 100644 hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_6_0/4700-mdm-link-history-error-messge-and-comma-delimited-inputs.yaml

diff --git a/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_6_0/4700-mdm-link-history-error-messge-and-comma-delimited-inputs.yaml b/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_6_0/4700-mdm-link-history-error-messge-and-comma-delimited-inputs.yaml
new file mode 100644
index 00000000000..5451276a03d
--- /dev/null
+++ b/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_6_0/4700-mdm-link-history-error-messge-and-comma-delimited-inputs.yaml
@@ -0,0 +1,5 @@
+---
+type: fix
+issue: 4700
+title: "When querying $mdm-link-history with no inputs, the error message is mislaeading.  Also, $mdm-link-history cannot handle comma-delimited inputs.
+        Both issues are now fixed."
diff --git a/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/BaseMdmProvider.java b/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/BaseMdmProvider.java
index cea40b6571e..b878cf8ad69 100644
--- a/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/BaseMdmProvider.java
+++ b/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/BaseMdmProvider.java
@@ -41,8 +41,11 @@ import org.springframework.data.domain.Page;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 
@@ -74,7 +77,7 @@ public abstract class BaseMdmProvider {
 
 	private void validateBothCannotBeNullOrEmpty(String theFirstName, List<IPrimitiveType<String>> theFirstList, String theSecondName, List<IPrimitiveType<String>> theSecondList) {
 		if ((theFirstList == null || theFirstList.isEmpty()) && (theSecondList == null || theSecondList.isEmpty())) {
-			throw new InvalidRequestException(Msg.code(2292) + "both ["+theFirstName+"] and ["+theSecondName+"] cannot be null or empty");
+			throw new InvalidRequestException(Msg.code(2292) + "Please include either ["+theFirstName+"]s, ["+theSecondName+"]s, or both in your search inputs.");
 		}
 	}
 
@@ -123,10 +126,17 @@ public abstract class BaseMdmProvider {
 	}
 
 	@Nonnull
-	protected List<String> convertToStringsIfNotNull(List<IPrimitiveType<String>> thePrimitiveTypeStrings) {
-		return thePrimitiveTypeStrings == null
-			? Collections.emptyList()
-			: thePrimitiveTypeStrings.stream().map(this::extractStringOrNull).collect(Collectors.toUnmodifiableList());
+	protected List<String> convertToStringsIncludingCommaDelimitedIfNotNull(List<IPrimitiveType<String>> thePrimitiveTypeStrings) {
+		if (thePrimitiveTypeStrings == null) {
+			return Collections.emptyList();
+		}
+
+		return thePrimitiveTypeStrings.stream()
+			.map(this::extractStringOrNull)
+			.filter(Objects::nonNull)
+			.map(input -> Arrays.asList(input.split(",")))
+			.flatMap(Collection::stream)
+			.collect(Collectors.toUnmodifiableList());
 	}
 
 	protected String extractStringOrNull(IPrimitiveType<String> theString) {
diff --git a/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/MdmLinkHistoryProviderDstu3Plus.java b/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/MdmLinkHistoryProviderDstu3Plus.java
index 06018d3585a..d8121176a55 100644
--- a/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/MdmLinkHistoryProviderDstu3Plus.java
+++ b/hapi-fhir-server-mdm/src/main/java/ca/uhn/fhir/mdm/provider/MdmLinkHistoryProviderDstu3Plus.java
@@ -53,8 +53,8 @@ public class MdmLinkHistoryProviderDstu3Plus extends BaseMdmProvider {
 													ServletRequestDetails theRequestDetails) {
 		validateMdmLinkHistoryParameters(theMdmGoldenResourceIds, theResourceIds);
 
-		final List<String> goldenResourceIdsToUse = convertToStringsIfNotNull(theMdmGoldenResourceIds);
-		final List<String> resourceIdsToUse = convertToStringsIfNotNull(theResourceIds);
+		final List<String> goldenResourceIdsToUse = convertToStringsIncludingCommaDelimitedIfNotNull(theMdmGoldenResourceIds);
+		final List<String> resourceIdsToUse = convertToStringsIncludingCommaDelimitedIfNotNull(theResourceIds);
 
 		final IBaseParameters retVal = ParametersUtil.newInstance(myFhirContext);