[Bug-fix] Translate JSONException to 400 instead of 500 (opensearch-project#3833)

Author: RyanL1997

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

@@ -96,6 +96,17 @@ public void sqlEnableSettingsTest() throws IOException {
     updateClusterSettings(new ClusterSetting(PERSISTENT, "plugins.ppl.enabled", null));
   }
 
+  @Test
+  public void testQueryEndpointShouldFailWithInvalidPayload() throws IOException {
+    exceptionRule.expect(ResponseException.class);
+    exceptionRule.expect(hasProperty("response", statusCode(400)));
+
+    Request post = new Request("POST", "/_plugins/_ppl");
+    post.setJsonEntity("{ \"query\": [\"search source=test\"] }");
+
+    client().performRequest(post);
+  }
+
   protected Request makePPLRequest(String query) {
     Request post = new Request("POST", "/_plugins/_ppl");
     post.setJsonEntity(String.format(Locale.ROOT, "{\n" + "  \"query\": \"%s\"\n" + "}", query));

integ-test/src/test/java/org/opensearch/sql/sql/QueryValidationIT.java

@@ -82,6 +82,27 @@ public void aggregationFunctionInSelectGroupByMultipleFields() throws IOExceptio
             "SELECT SUM(age) FROM opensearch-sql_test_index_account GROUP BY state.keyword");
   }
 
+  @Test
+  public void testSqlQueryWithArrayPayloadShouldFailWithBadRequest() throws IOException {
+    expectResponseException()
+        .hasStatusCode(BAD_REQUEST)
+        .hasErrorType("IllegalArgumentException")
+        .containsMessage("Failed to parse request payload");
+
+    whenExecuteMalformedPayload();
+  }
+
+  private static void whenExecuteMalformedPayload() throws IOException {
+    Request request = new Request("POST", QUERY_API_ENDPOINT);
+    request.setJsonEntity("{ \"query\": [\"SELECT * FROM opensearch-sql_test_index_account\"] }");
+
+    RequestOptions.Builder restOptionsBuilder = RequestOptions.DEFAULT.toBuilder();
+    restOptionsBuilder.addHeader("Content-Type", "application/json");
+    request.setOptions(restOptionsBuilder);
+
+    client().performRequest(request);
+  }
+
   public ResponseExceptionAssertion expectResponseException() {
     return new ResponseExceptionAssertion(exceptionRule);
   }

legacy/src/main/java/org/opensearch/sql/legacy/request/SqlRequestFactory.java

@@ -53,19 +53,19 @@ private static SqlRequest parseSqlRequestFromPayload(RestRequest restRequest) {
       if (jsonContent.has(SQL_CURSOR_FIELD_NAME)) {
         return new SqlRequest(jsonContent.getString(SQL_CURSOR_FIELD_NAME));
       }
+      String sql = jsonContent.getString(SQL_FIELD_NAME);
+
+      if (jsonContent.has(PARAM_FIELD_NAME)) { // is a PreparedStatement
+        JSONArray paramArray = jsonContent.getJSONArray(PARAM_FIELD_NAME);
+        List<PreparedStatementRequest.PreparedStatementParameter> parameters =
+            parseParameters(paramArray);
+        return new PreparedStatementRequest(
+            sql, validateAndGetFetchSize(jsonContent), jsonContent, parameters);
+      }
+      return new SqlRequest(sql, validateAndGetFetchSize(jsonContent), jsonContent);
     } catch (JSONException e) {
       throw new IllegalArgumentException("Failed to parse request payload", e);
     }
-    String sql = jsonContent.getString(SQL_FIELD_NAME);
-
-    if (jsonContent.has(PARAM_FIELD_NAME)) { // is a PreparedStatement
-      JSONArray paramArray = jsonContent.getJSONArray(PARAM_FIELD_NAME);
-      List<PreparedStatementRequest.PreparedStatementParameter> parameters =
-          parseParameters(paramArray);
-      return new PreparedStatementRequest(
-          sql, validateAndGetFetchSize(jsonContent), jsonContent, parameters);
-    }
-    return new SqlRequest(sql, validateAndGetFetchSize(jsonContent), jsonContent);
   }
 
   private static Integer validateAndGetFetchSize(JSONObject jsonContent) {

plugin/src/main/java/org/opensearch/sql/plugin/request/PPLQueryRequestFactory.java

@@ -59,24 +59,24 @@ private static PPLQueryRequest parsePPLRequestFromPayload(RestRequest restReques
     boolean pretty = getPrettyOption(restRequest.params());
     try {
       jsonContent = new JSONObject(content);
+      PPLQueryRequest pplRequest =
+          new PPLQueryRequest(
+              jsonContent.getString(PPL_FIELD_NAME),
+              jsonContent,
+              restRequest.path(),
+              format.getFormatName());
+      // set sanitize option if csv format
+      if (format.equals(Format.CSV)) {
+        pplRequest.sanitize(getSanitizeOption(restRequest.params()));
+      }
+      // set pretty option
+      if (pretty) {
+        pplRequest.style(JsonResponseFormatter.Style.PRETTY);
+      }
+      return pplRequest;
     } catch (JSONException e) {
       throw new IllegalArgumentException("Failed to parse request payload", e);
     }
-    PPLQueryRequest pplRequest =
-        new PPLQueryRequest(
-            jsonContent.getString(PPL_FIELD_NAME),
-            jsonContent,
-            restRequest.path(),
-            format.getFormatName());
-    // set sanitize option if csv format
-    if (format.equals(Format.CSV)) {
-      pplRequest.sanitize(getSanitizeOption(restRequest.params()));
-    }
-    // set pretty option
-    if (pretty) {
-      pplRequest.style(JsonResponseFormatter.Style.PRETTY);
-    }
-    return pplRequest;
   }
 
   private static Format getFormat(Map<String, String> requestParams, String path) {