Fix parsing of dot-containing field names

integ-test/src/yamlRestTest/resources/rest-api-spec/test/issues/4896.yml

@@ -0,0 +1,89 @@
+# Issue: https://github.com/opensearch-project/sql/issues/4896
+# ArrayIndexOutOfBoundsException when querying index with dot-only field name
+#
+# Root cause: When a document has a field name that is just "." (a single dot),
+# the JsonPath constructor's split("\\.") returns an empty array, causing
+# paths.get(0) to crash with ArrayIndexOutOfBoundsException.
+#
+# This can happen when an index has a disabled object field (enabled: false),
+# which allows storing documents without validating inner field names.
+#
+# Fix: When split returns empty array, treat the original string as a literal
+# field name, allowing the data to be returned properly.
+
+setup:
+  - do:
+      query.settings:
+        body:
+          transient:
+            plugins.calcite.enabled: true
+  # Create index with disabled object field
+  - do:
+      indices.create:
+        index: test_disabled_object_4896
+        body:
+          mappings:
+            properties:
+              log:
+                type: object
+                enabled: false
+              "@timestamp":
+                type: date
+              message:
+                type: text
+
+  # Index document with "." field name inside disabled object
+  # OpenSearch allows this because the object is disabled (no validation of inner fields)
+  - do:
+      index:
+        index: test_disabled_object_4896
+        id: 1
+        refresh: true
+        body:
+          "@timestamp": "2025-11-26T17:10:00.000Z"
+          message: "test message"
+          log:
+            ".": "dot field value"
+
+---
+teardown:
+  - do:
+      query.settings:
+        body:
+          transient:
+            plugins.calcite.enabled: false
+  - do:
+      indices.delete:
+        index: test_disabled_object_4896
+
+---
+"Query index with dot-only field name should return actual value":
+  - skip:
+      features:
+        - headers
+
+  # Test 1: Query valid fields - should succeed
+  # Before fix: This would crash because the entire document is parsed
+  # After fix: Query succeeds, all fields returned normally
+  - do:
+      headers:
+        Content-Type: 'application/json'
+      ppl:
+        body:
+          query: source=test_disabled_object_4896 | fields @timestamp, message
+  - match: { "total": 1 }
+  - match: { "datarows.0.0": "2025-11-26 17:10:00" }
+  - match: { "datarows.0.1": "test message" }
+
+  # Test 2: Query the log field with "." subfield
+  # Before fix: ArrayIndexOutOfBoundsException crash
+  # After fix: Returns the log object with the "." field containing actual value
+  - do:
+      headers:
+        Content-Type: 'application/json'
+      ppl:
+        body:
+          query: source=test_disabled_object_4896 | fields log
+  - match: { "total": 1 }
+  # The log field should contain the "." subfield with its value
+  - match: { "datarows.0.0": { ".": "dot field value" } }

opensearch/src/main/java/org/opensearch/sql/opensearch/data/value/OpenSearchExprValueFactory.java

@@ -412,7 +412,14 @@ static class JsonPath {
     private final List<String> paths;
 
     public JsonPath(String rawPath) {
-      this.paths = List.of(rawPath.split("\\."));
+      String[] parts = rawPath.split("\\.");
+      // If split returns empty array (e.g., "." or ".."), treat the original string as a literal
+      // field name instead of a path separator
+      if (parts.length == 0) {
+        this.paths = List.of(rawPath);
+      } else {
+        this.paths = List.of(parts);
+      }
     }
 
     public JsonPath(List<String> paths) {

opensearch/src/test/java/org/opensearch/sql/opensearch/data/value/OpenSearchExprValueFactoryTest.java

@@ -1041,6 +1041,41 @@ public void testPopulateValueRecursive() {
     assertEquals(expectedValue, tupleValue);
   }
 
+  @Test
+  public void constructWithDotOnlyFieldNameReturnsValue() {
+    // Field name "." (single dot) should return the actual value, not crash or return null
+    // This can happen with disabled object fields in OpenSearch
+    Map<String, ExprValue> result = tupleValue("{\"structV\":{\".\":\"value\"}}");
+    ExprValue structValue = result.get("structV");
+    // The "." field should contain the actual value
+    assertEquals(stringValue("value"), structValue.tupleValue().get("."));
+  }
+
+  @Test
+  public void constructWithMultipleDotsFieldNameReturnsValue() {
+    // Field name ".." (multiple dots) should also return the actual value
+    Map<String, ExprValue> result = tupleValue("{\"structV\":{\"..\":\"value\"}}");
+    ExprValue structValue = result.get("structV");
+    assertEquals(stringValue("value"), structValue.tupleValue().get(".."));
+  }
+
+  @Test
+  public void constructWithDotFieldAlongsideValidFieldsReturnsAll() {
+    // Both dot field and valid fields should be returned
+    Map<String, ExprValue> result =
+        tupleValue(
+            "{\"structV\":{\".\":\"dotValue\",\"id\":1,\"state\":\"WA\"},\"stringV\":\"test\"}");
+
+    // stringV field should be returned normally
+    assertEquals(stringValue("test"), result.get("stringV"));
+
+    // All fields inside structV should be returned
+    ExprValue structValue = result.get("structV");
+    assertEquals(stringValue("dotValue"), structValue.tupleValue().get("."));
+    assertEquals(integerValue(1), structValue.tupleValue().get("id"));
+    assertEquals(stringValue("WA"), structValue.tupleValue().get("state"));
+  }
+
   public Map<String, ExprValue> tupleValue(String jsonString) {
     final ExprValue construct = exprValueFactory.construct(jsonString, false);
     return construct.tupleValue();