[Reporting] Correct the docvalue_fields params in the search query Download CSV from Dashboard Panel (#52833)

* fix the bug and add a test

* fix query bug of empty array

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

Author: tsullivan

x-pack/legacy/plugins/reporting/export_types/csv/types.d.ts

@@ -6,10 +6,21 @@
 
 import { JobDocPayload, JobParamPostPayload, ConditionalHeaders, RequestFacade } from '../../types';
 
+interface DocValueField {
+  field: string;
+  format: string;
+}
+
+interface SortOptions {
+  order: string;
+  unmapped_type: string;
+}
+
 export interface JobParamPostPayloadDiscoverCsv extends JobParamPostPayload {
   state?: {
     query: any;
-    sort: any[];
+    sort: Array<Record<string, SortOptions>>;
+    docvalue_fields: DocValueField[];
   };
 }
 

x-pack/legacy/plugins/reporting/export_types/csv_from_savedobject/server/lib/generate_csv_search.ts

@@ -84,10 +84,11 @@ export async function generateCsvSearch(
 
   let payloadQuery: QueryFilter | undefined;
   let payloadSort: any[] = [];
+  let docValueFields: any[] | undefined;
   if (jobParams.post && jobParams.post.state) {
     ({
       post: {
-        state: { query: payloadQuery, sort: payloadSort = [] },
+        state: { query: payloadQuery, sort: payloadSort = [], docvalue_fields: docValueFields },
       },
     } = jobParams);
   }
@@ -119,7 +120,15 @@ export async function generateCsvSearch(
         },
       };
     }, {});
-  const docValueFields = indexPatternTimeField ? [indexPatternTimeField] : undefined;
+
+  if (indexPatternTimeField) {
+    if (docValueFields) {
+      docValueFields = [indexPatternTimeField].concat(docValueFields);
+    } else {
+      docValueFields = [indexPatternTimeField];
+    }
+  }
+
   const searchRequest: SearchRequest = {
     index: esIndex,
     body: {