Allow assigning ReferenceFieldValue instances

2 files changed, 43 insertions, 0 deletions

diff --git a/document/src/main/java/com/yahoo/document/datatypes/ReferenceFieldValue.java b/document/src/main/java/com/yahoo/document/datatypes/ReferenceFieldValue.java
index 3adce1fd1ed..fc7981905aa 100644
--- a/document/src/main/java/com/yahoo/document/datatypes/ReferenceFieldValue.java
+++ b/document/src/main/java/com/yahoo/document/datatypes/ReferenceFieldValue.java
@@ -97,6 +97,8 @@ public class ReferenceFieldValue extends FieldValue {
     public void assign(Object o) {
         if (o == null) {
             clear();
+        } else if (o instanceof ReferenceFieldValue) {
+            assignFromFieldValue((ReferenceFieldValue) o);
         } else if (o instanceof DocumentId) {
             setDocumentId((DocumentId) o);
         } else {
@@ -106,6 +108,15 @@ public class ReferenceFieldValue extends FieldValue {
         }
     }
 
+    private void assignFromFieldValue(ReferenceFieldValue rhs) {
+        if (!getDataType().equals(rhs.getDataType())) {
+            throw new IllegalArgumentException(String.format(
+                    "Can't assign reference of type %s to reference of type %s",
+                    rhs.getDataType().getName(), getDataType().getName()));
+        }
+        rhs.getDocumentId().ifPresent(this::setDocumentId);
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) {
diff --git a/document/src/test/java/com/yahoo/document/datatypes/ReferenceFieldValueTestCase.java b/document/src/test/java/com/yahoo/document/datatypes/ReferenceFieldValueTestCase.java
index 7c30ff45fa5..456ab7adc41 100644
--- a/document/src/test/java/com/yahoo/document/datatypes/ReferenceFieldValueTestCase.java
+++ b/document/src/test/java/com/yahoo/document/datatypes/ReferenceFieldValueTestCase.java
@@ -6,7 +6,9 @@ import com.yahoo.document.DocumentId;
 import com.yahoo.document.DocumentType;
 import com.yahoo.document.Field;
 import com.yahoo.document.ReferenceDataType;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -19,6 +21,9 @@ import static org.junit.Assert.assertTrue;
  */
 public class ReferenceFieldValueTestCase {
 
+    @Rule
+    public final ExpectedException exceptionRule = ExpectedException.none();
+
     private static DocumentType createDocumentType(String name) {
         DocumentType type = new DocumentType(name);
         type.addField(new Field("foo", DataType.STRING));
@@ -100,6 +105,33 @@ public class ReferenceFieldValueTestCase {
     }
 
     @Test
+    public void can_assign_empty_reference_field_value_instance__to_existing_reference() {
+        ReferenceFieldValue existing = new ReferenceFieldValue(referenceTypeFoo());
+        ReferenceFieldValue newValue = new ReferenceFieldValue(referenceTypeFoo());
+        // Logically a no-op, but still worth testing.
+        existing.assign(newValue);
+        assertEquals(newValue, existing);
+    }
+
+    @Test
+    public void can_assign_reference_field_value_instance__with_id_to_existing_reference() {
+        ReferenceFieldValue existing = new ReferenceFieldValue(referenceTypeFoo());
+        ReferenceFieldValue newValue = new ReferenceFieldValue(referenceTypeFoo(), docId("id:ns:foo::toad"));
+        existing.assign(newValue);
+        assertEquals(newValue, existing);
+    }
+
+    @Test
+    public void assigning_reference_field_with_different_type_to_existing_reference_throws_exception() {
+        ReferenceFieldValue existing = new ReferenceFieldValue(referenceTypeFoo());
+        ReferenceFieldValue newValue = new ReferenceFieldValue(referenceTypeBar());
+        exceptionRule.expect(IllegalArgumentException.class);
+        exceptionRule.expectMessage("Can't assign reference of type Reference<bar> " +
+                "to reference of type Reference<foo>");
+        existing.assign(newValue);
+    }
+
+    @Test
     public void reference_value_can_be_cleared() {
         ReferenceFieldValue value = new ReferenceFieldValue(referenceTypeFoo(), docId("id:ns:foo::yoshi-egg-feast"));
         value.clear();