From fcde2a558cebb9d664ecdc56d4d29b8d8b8a2ce3 Mon Sep 17 00:00:00 2001
From: xinyual <xinyual@amazon.com>
Date: Sat, 25 Nov 2023 22:17:56 +0800
Subject: [PATCH] allow zero index

Signed-off-by: xinyual <xinyual@amazon.com>
---
 .../opensearch/ml/engine/tools/PPLTool.java   | 32 ++++++++++++-------
 1 file changed, 21 insertions(+), 11 deletions(-)

diff --git a/ml-algorithms/src/main/java/org/opensearch/ml/engine/tools/PPLTool.java b/ml-algorithms/src/main/java/org/opensearch/ml/engine/tools/PPLTool.java
index 6c4887dc11..fcaad98d87 100644
--- a/ml-algorithms/src/main/java/org/opensearch/ml/engine/tools/PPLTool.java
+++ b/ml-algorithms/src/main/java/org/opensearch/ml/engine/tools/PPLTool.java
@@ -214,19 +214,29 @@ private String constructTableInfo(SearchHit [] searchHits, Map<String, MappingMe
         Map<String, Object> mappingSource = (Map<String, Object>) mappingMetadata.getSourceAsMap().get("properties");
         Map<String, String> fieldsToType = new HashMap<>();
         extractNamesTypes(mappingSource, fieldsToType, "");
-
-        SearchHit hit = searchHits[0];
-        Map<String, Object> sampleSource = hit.getSourceAsMap();
-        Map<String, String> fieldsToSample = new HashMap<>();
-        for (String key : fieldsToType.keySet()) {
-            fieldsToSample.put(key, "");
-        }
-        extractSamples(sampleSource, fieldsToSample, "");
         StringJoiner tableInfoJoiner = new StringJoiner("\n");
 
-        for (String key : fieldsToType.keySet()) {
-            String line = "- " + key + ": " + fieldsToType.get(key) + " (" + fieldsToSample.get(key) + ")";
-            tableInfoJoiner.add(line);
+        if (searchHits.length > 0) {
+            SearchHit hit = searchHits[0];
+            Map<String, Object> sampleSource = hit.getSourceAsMap();
+            Map<String, String> fieldsToSample = new HashMap<>();
+            for (String key : fieldsToType.keySet()) {
+                fieldsToSample.put(key, "");
+            }
+            extractSamples(sampleSource, fieldsToSample, "");
+
+
+            for (String key : fieldsToType.keySet()) {
+                String line = "- " + key + ": " + fieldsToType.get(key) + " (" + fieldsToSample.get(key) + ")";
+                tableInfoJoiner.add(line);
+            }
+        }
+        else
+        {
+            for (String key : fieldsToType.keySet()) {
+                String line = "- " + key + ": " + fieldsToType.get(key);
+                tableInfoJoiner.add(line);
+            }
         }
 
         String tableInfo = tableInfoJoiner.toString();