add remove method to field list mutator (#4088)

* add remove method to field list mutator

* add test and Msg.code

* test passes

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

hapi-fhir-base/src/main/java/ca/uhn/fhir/context/BaseRuntimeChildDefinition.java

@@ -89,6 +89,15 @@ public abstract class BaseRuntimeChildDefinition {
 		void addValue(IBase theTarget, IBase theValue);
 
 		void setValue(IBase theTarget, IBase theValue);
+
+		/**
+		 * Remove an item from a list of values
+		 * @param theTarget field to remove the item from (e.g. patient.name)
+		 * @param theIndex the index of the item to be removed (e.g. 1 for patient.name[1])
+		 */
+		default void remove(IBase theTarget, int theIndex) {
+			// implemented in subclasses
+		}
 	}
 
 	BaseRuntimeElementDefinition<?> findResourceReferenceDefinition(Map<Class<? extends IBase>, BaseRuntimeElementDefinition<?>> theClassToElementDefinitions) {

hapi-fhir-base/src/main/java/ca/uhn/fhir/context/BaseRuntimeDeclaredChildDefinition.java

@@ -177,6 +177,18 @@ public abstract class BaseRuntimeDeclaredChildDefinition extends BaseRuntimeChil
 		public void setValue(IBase theTarget, IBase theValue) {
 			addValue(theTarget, theValue, true);
 		}
+
+		@Override
+		public void remove(IBase theTarget, int theIndex) {
+			List<IBase> existingList = (List<IBase>) getFieldValue(theTarget, myField);
+			if (existingList == null) {
+				throw new IndexOutOfBoundsException(Msg.code(2143) + "Can not remove element at index " + theIndex + " from list - List is null");
+			}
+			if (theIndex >= existingList.size()) {
+				throw new IndexOutOfBoundsException(Msg.code(2144) + "Can not remove element at index " + theIndex + " from list - List size is " + existingList.size());
+			}
+			existingList.remove(theIndex);
+		}
 	}
 
 	private final class FieldPlainAccessor implements IAccessor {
@@ -205,6 +217,11 @@ public abstract class BaseRuntimeDeclaredChildDefinition extends BaseRuntimeChil
 		public void setValue(IBase theTarget, IBase theValue) {
 			addValue(theTarget, theValue);
 		}
+
+		@Override
+		public void remove(IBase theTarget, int theIndex) {
+			throw new UnsupportedOperationException(Msg.code(2142) + "Remove by index can only be called on a list-valued field.  '" + myField.getName() + "' is a single-valued field.");
+		}
 	}
 
 	private static void setFieldValue(IBase theTarget, Object theValue, Field theField) {

hapi-fhir-structures-r4/src/test/java/ca/uhn/fhir/context/BaseRuntimeElementDefinitionTest.java

@@ -1,17 +1,21 @@
 package ca.uhn.fhir.context;
 
 import ca.uhn.fhir.i18n.Msg;
+import org.hl7.fhir.r4.model.Enumerations;
+import org.hl7.fhir.r4.model.Patient;
 import org.junit.jupiter.api.Test;
 
-import static org.junit.jupiter.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class BaseRuntimeElementDefinitionTest {
 
+	private static FhirContext ourFhirContext = FhirContext.forR4Cached();
+
 	@Test
 	public void testNewInstance_InvalidArgumentType() {
-		FhirContext ctx = FhirContext.forR4();
 
-		BaseRuntimeElementDefinition<?> def = ctx.getElementDefinition("string");
+		BaseRuntimeElementDefinition<?> def = ourFhirContext.getElementDefinition("string");
 
 		try {
 			def.newInstance(123);
@@ -21,4 +25,36 @@ public class BaseRuntimeElementDefinitionTest {
 		}
 	}
 
+	@Test
+	void mutator_remove() {
+		Patient patient = new Patient();
+		patient.addName().setFamily("A1");
+		patient.addName().setFamily("A2");
+
+		assertEquals(2, patient.getName().size());
+		assertEquals("A1", patient.getName().get(0).getFamily());
+		RuntimeResourceDefinition def = ourFhirContext.getResourceDefinition(patient);
+		BaseRuntimeChildDefinition child = def.getChildByName("name");
+		BaseRuntimeChildDefinition.IMutator mutator = child.getMutator();
+
+		mutator.remove(patient, 0);
+		assertEquals(1, patient.getName().size());
+		assertEquals("A2", patient.getName().get(0).getFamily());
+	}
+
+	@Test
+	void mutator_remov_nonList() {
+		Patient patient = new Patient();
+		patient.setGender(Enumerations.AdministrativeGender.MALE);
+
+		RuntimeResourceDefinition def = ourFhirContext.getResourceDefinition(patient);
+		BaseRuntimeChildDefinition child = def.getChildByName("gender");
+		BaseRuntimeChildDefinition.IMutator mutator = child.getMutator();
+		try {
+			mutator.remove(patient, 0);
+			fail();
+		} catch (UnsupportedOperationException e) {
+			assertEquals("HAPI-2142: Remove by index can only be called on a list-valued field.  'gender' is a single-valued field.", e.getMessage());
+		}
+	}
 }