[Backport 2.x] Guard against invalid sorting fields in report generation

server/routes/utils/dataReportHelpers.ts

@@ -15,20 +15,20 @@
 } from '../../../../../src/plugins/data/common';
 import { ExcelBuilder } from './excelBuilder';
 
 export var metaData = {
   saved_search_id: <string>null,
   report_format: <string>null,
   start: <string>null,
   end: <string>null,
   fields: <string>null,
   type: <string>null,
   timeFieldName: <string>null,
   sorting: <string>null,
   fields_exist: <boolean>false,
   selectedFields: <any>[],
   paternName: <string>null,
   searchSourceJSON: <any>[],
   dateFields: <any>[],
 };
 
 // Get the selected columns by the user.
@@ -51,7 +51,7 @@
 // Build the OpenSearch query from the meta data
 // is_count is set to 1 if we building the count query but 0 if we building the fetch data query
 export const buildRequestBody = (
   report: any,
   allowLeadingWildcards: boolean,
   is_count: number
 ) => {
@@ -90,11 +90,21 @@
     .query(esbBoolQuery)
     .version(true);
 
-  if (report._source.sorting.length > 0) {
-    const sortings: Sort[] = report._source.sorting.map((element: string[]) => {
+  let sorting: string[][] = report._source.sorting;
+
+  // We expect a list of [field, order] pairs for sorting. In some migration paths, though it's not
+  // clear why, this list can get unnested in the case of one sort, [["field", "asc"]] becomes
+  // ["field", "asc"]. The true root cause remains a mystery, so we work around it.
+  // See: https://github.com/opensearch-project/dashboards-reporting/issues/371
+  if (sorting.length > 0 && typeof sorting[0] === "string") {
+    sorting = [(sorting as unknown as string[])];
+  }
+
+  if (sorting.length > 0) {
+    const sorts: Sort[] = sorting.map((element: string[]) => {
       return esb.sort(element[0], element[1]);
     });
-    esbSearchQuery.sorts(sortings);
+    esbSearchQuery.sorts(sorts);
   }
 
   // add selected fields to query
@@ -118,13 +128,13 @@
 
 // Fetch the data from OpenSearch
 export const getOpenSearchData = (
   arrayHits: any,
   report: { _source: any },
   params: { excel: any; limit: number },
   dateFormat: string,
   timezone: string
 ) => {
   let hits: any = [];
   for (let valueRes of arrayHits) {
     for (let data of valueRes.hits) {
       const fields = data.fields;
@@ -214,7 +224,7 @@
 
 // Convert the data to Csv format
 export const convertToCSV = async (dataset, csvSeparator) => {
   let convertedData: any = [];
   const options = {
     delimiter: { field: csvSeparator, eol: '\n' },
     emptyFieldValue: ' ',
@@ -242,7 +252,7 @@
   return result;
 }
 
 function flattenObject(obj = {}, parentKey = '', result: any = {}) {
   for (const [key, value] of Object.entries(obj)) {
     const newKey = parentKey ? `${parentKey}.${key}` : key;