1 files changed, 12 insertions, 1 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/ToStringFunction.java b/container-search/src/main/java/com/yahoo/search/grouping/request/ToStringFunction.java
index 7f4e48c8d81..dd7bd0b5250 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/request/ToStringFunction.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/ToStringFunction.java
@@ -8,6 +8,7 @@ import java.util.Arrays;
  * long. If the argument can not be converted, this function returns 0.
  *
  * @author baldersheim
+ * @author bratseth
  */
 public class ToStringFunction extends FunctionNode {
 
@@ -17,6 +18,16 @@ public class ToStringFunction extends FunctionNode {
      * @param exp The expression to evaluate.
      */
     public ToStringFunction(GroupingExpression exp) {
-        super("tostring", Arrays.asList(exp));
+        this(null, null, exp);
     }
+
+    private ToStringFunction(String label, Integer level, GroupingExpression exp) {
+        super("tostring", label, level, Arrays.asList(exp));
+    }
+
+    @Override
+    public ToStringFunction copy() {
+        return new ToStringFunction(getLabel(), getLevelOrNull(), getArg(0).copy());
+    }
+
 }