From 2613af4b65f9e5fe9b932bd60c30976c0a667b8a Mon Sep 17 00:00:00 2001
From: Matthias Wilhelm <matthias.wilhelm@elastic.co>
Date: Mon, 14 Sep 2020 16:23:26 +0200
Subject: [PATCH] [Discover] Convert legacy sort to be compatible with multi
 sort (#76986) (#77334)

---
 .../angular/doc_table/lib/get_sort.test.ts           |  5 +++++
 .../application/angular/doc_table/lib/get_sort.ts    | 12 +++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.test.ts b/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.test.ts
index a32af8fe43dc1..4db1d2b175d0b 100644
--- a/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.test.ts
+++ b/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.test.ts
@@ -58,6 +58,11 @@ describe('docTable', function () {
       expect(getSort([['foo', 'bar']], indexPattern)).toEqual([]);
       expect(getSort([{ foo: 'bar' }], indexPattern)).toEqual([]);
     });
+
+    test('should convert a legacy sort to an array of objects', function () {
+      expect(getSort(['foo', 'desc'], indexPattern)).toEqual([{ foo: 'desc' }]);
+      expect(getSort(['foo', 'asc'], indexPattern)).toEqual([{ foo: 'asc' }]);
+    });
   });
 
   describe('getSortArray function', function () {
diff --git a/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.ts b/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.ts
index c28519692318e..73ae691529e2b 100644
--- a/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.ts
+++ b/src/plugins/discover/public/application/angular/doc_table/lib/get_sort.ts
@@ -46,6 +46,12 @@ function createSortObject(
   }
 }
 
+export function isLegacySort(sort: SortPair[] | SortPair): sort is SortPair {
+  return (
+    sort.length === 2 && typeof sort[0] === 'string' && (sort[1] === 'desc' || sort[1] === 'asc')
+  );
+}
+
 /**
  * Take a sorting array and make it into an object
  * @param {array} sort two dimensional array [[fieldToSort, directionToSort]]
@@ -53,8 +59,12 @@ function createSortObject(
  * @param {object} indexPattern used for determining default sort
  * @returns Array<{object}> an array of sort objects
  */
-export function getSort(sort: SortPair[], indexPattern: IndexPattern): SortPairObj[] {
+export function getSort(sort: SortPair[] | SortPair, indexPattern: IndexPattern): SortPairObj[] {
   if (Array.isArray(sort)) {
+    if (isLegacySort(sort)) {
+      // To stay compatible with legacy sort, which just supported a single sort field
+      return [{ [sort[0]]: sort[1] }];
+    }
     return sort
       .map((sortPair: SortPair) => createSortObject(sortPair, indexPattern))
       .filter((sortPairObj) => typeof sortPairObj === 'object') as SortPairObj[];