1 files changed, 15 insertions, 1 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/grouping/request/DateFunction.java b/container-search/src/main/java/com/yahoo/search/grouping/request/DateFunction.java
index b3a4c451b6b..0c2c4928a91 100644
--- a/container-search/src/main/java/com/yahoo/search/grouping/request/DateFunction.java
+++ b/container-search/src/main/java/com/yahoo/search/grouping/request/DateFunction.java
@@ -2,12 +2,14 @@
 package com.yahoo.search.grouping.request;
 
 import java.util.Arrays;
+import java.util.stream.Collectors;
 
 /**
  * This class represents a timestamp-formatter function in a {@link GroupingExpression}. It evaluates to a string on the
  * form "YYYY-MM-DD" of the result of the argument.
  *
  * @author Simon Thoresen Hult
+ * @author bratseth
  */
 public class DateFunction extends FunctionNode {
 
@@ -17,6 +19,18 @@ public class DateFunction extends FunctionNode {
      * @param exp The expression to evaluate, must evaluate to a long.
      */
     public DateFunction(GroupingExpression exp) {
-        super("time.date", Arrays.asList(exp));
+        this(null, null, exp);
     }
+
+    private DateFunction(String label, Integer level, GroupingExpression exp) {
+        super("time.date", label, level, Arrays.asList(exp));
+    }
+
+    @Override
+    public DateFunction copy() {
+        return new DateFunction(getLabel(),
+                                getLevelOrNull(),
+                                getArg(0).copy());
+    }
+
 }