From 4c53a14ab59cea262f3e62ce21f81d915c1653cc Mon Sep 17 00:00:00 2001
From: jeffganmr <106223805+jeffganmr@users.noreply.github.com>
Date: Mon, 24 Feb 2025 23:22:48 +0800
Subject: [PATCH] fix stale data in synthetic source for string stored field
 (#123105)

---
 docs/changelog/123105.yaml                    |  6 +++
 .../mapper/StringStoredFieldFieldLoader.java  |  2 +-
 .../StringStoredFieldFieldLoaderTests.java    | 52 +++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 docs/changelog/123105.yaml
 create mode 100644 server/src/test/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoaderTests.java

diff --git a/docs/changelog/123105.yaml b/docs/changelog/123105.yaml
new file mode 100644
index 0000000000000..f763b51436434
--- /dev/null
+++ b/docs/changelog/123105.yaml
@@ -0,0 +1,6 @@
+pr: 123105
+summary: fix stale data in synthetic source for string stored field
+area: Mapping
+type: bug
+issues:
+  - 123110
diff --git a/server/src/main/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoader.java b/server/src/main/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoader.java
index c8a8dd4b4a898..c114a1619c7a9 100644
--- a/server/src/main/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoader.java
+++ b/server/src/main/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoader.java
@@ -54,7 +54,7 @@ public final void write(XContentBuilder b) throws IOException {
             case 1:
                 b.field(simpleName);
                 write(b, values.get(0));
-                return;
+                break;
             default:
                 b.startArray(simpleName);
                 for (Object value : values) {
diff --git a/server/src/test/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoaderTests.java b/server/src/test/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoaderTests.java
new file mode 100644
index 0000000000000..dcd6c35ab1700
--- /dev/null
+++ b/server/src/test/java/org/elasticsearch/index/mapper/StringStoredFieldFieldLoaderTests.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.index.mapper;
+
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.xcontent.XContentBuilder;
+import org.elasticsearch.xcontent.XContentType;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class StringStoredFieldFieldLoaderTests extends ESTestCase {
+
+    public void testLoadStoredFieldAndReset() throws IOException {
+        var sfl = new StringStoredFieldFieldLoader("foo", "foo") {
+            @Override
+            protected void write(XContentBuilder b, Object value) throws IOException {
+                b.value((String) value);
+            }
+        };
+
+        var storedFieldLoaders = sfl.storedFieldLoaders().collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+        storedFieldLoaders.get("foo").load(List.of("one"));
+
+        var result = XContentBuilder.builder(XContentType.JSON.xContent());
+        result.startObject();
+        sfl.write(result);
+        result.endObject();
+
+        assertEquals("""
+            {"foo":"one"}""", Strings.toString(result));
+
+        var empty = XContentBuilder.builder(XContentType.JSON.xContent());
+        empty.startObject();
+        // reset() should have been called after previous write
+        sfl.write(empty);
+        empty.endObject();
+
+        assertEquals("{}", Strings.toString(empty));
+    }
+
+}