added null test

Signed-off-by: Kenrick Yap <[email protected]>

Author: kenrickyap

core/src/main/java/org/opensearch/sql/utils/JsonUtils.java

@@ -16,6 +16,11 @@ public class JsonUtils {
    */
   public static ExprValue isValidJson(ExprValue jsonExprValue) {
     ObjectMapper objectMapper = new ObjectMapper();
+
+    if (jsonExprValue.isNull() || jsonExprValue.isMissing()) {
+      return ExprValueUtils.LITERAL_FALSE;
+    }
+
     try {
       objectMapper.readTree(jsonExprValue.stringValue());
       return ExprValueUtils.LITERAL_TRUE;

integ-test/src/test/java/org/opensearch/sql/ppl/JsonFunctionsIT.java

@@ -50,6 +50,6 @@ public void test_not_json_valid() throws IOException {
                 "source=%s | where not json_valid(json_string) | fields test_name",
                 TEST_INDEX_JSON_TEST));
     verifySchema(result, schema("test_name", null, "string"));
-    verifyDataRows(result, rows("json invalid object"));
+    verifyDataRows(result, rows("json invalid object"), rows("json null"));
   }
 }

integ-test/src/test/resources/json_test.json

@@ -10,3 +10,5 @@
 {"test_name":"json empty string","json_string":""}
 {"index":{"_id":"5"}}
 {"test_name":"json invalid object", "json_string":"{\"invalid\":\"json\", \"string\"}"}
+{"index":{"_id":"6"}}
+{"test_name":"json null", "json_string":null}