From 9eef9c9db478831a4d427a8d9bbf1c348fb1b19f Mon Sep 17 00:00:00 2001
From: Phil Kuang <pkuang@factset.com>
Date: Thu, 12 May 2022 21:32:44 -0400
Subject: [PATCH] fix(elasticSearch): do not define pageCursor on last page

Signed-off-by: Phil Kuang <pkuang@factset.com>
---
 .changeset/pretty-hornets-listen.md           |  5 +++
 .../engines/ElasticSearchSearchEngine.test.ts | 44 +++++++++++++++++++
 .../src/engines/ElasticSearchSearchEngine.ts  |  2 +-
 3 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/pretty-hornets-listen.md

diff --git a/.changeset/pretty-hornets-listen.md b/.changeset/pretty-hornets-listen.md
new file mode 100644
index 0000000000..6e0701e617
--- /dev/null
+++ b/.changeset/pretty-hornets-listen.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-search-backend-module-elasticsearch': patch
+---
+
+Fix issue where `nextPageCursor` is defined on the last page of results
diff --git a/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.test.ts b/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.test.ts
index 134de5a9f6..24ceec2875 100644
--- a/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.test.ts
+++ b/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.test.ts
@@ -438,6 +438,50 @@ describe('ElasticSearchSearchEngine', () => {
       });
     });
 
+    it('should perform search query with less results than one page', async () => {
+      mock.clear({
+        method: 'POST',
+        path: '/*__search/_search',
+      });
+      mock.add(
+        {
+          method: 'POST',
+          path: '/*__search/_search',
+        },
+        () => {
+          return {
+            hits: {
+              total: { value: 20, relation: 'eq' },
+              hits: Array(20)
+                .fill(null)
+                .map((_, i) => ({
+                  _index: 'mytype-index__',
+                  _source: {
+                    value: `${i}`,
+                  },
+                })),
+            },
+          };
+        },
+      );
+
+      const mockedSearchResult = await testSearchEngine.query({
+        term: 'testTerm',
+        filters: {},
+      });
+
+      expect(mockedSearchResult).toMatchObject({
+        results: expect.arrayContaining(
+          Array(20)
+            .fill(null)
+            .map((_, i) => ({
+              type: 'mytype',
+              document: { value: `${i}` },
+            })),
+        ),
+      });
+    });
+
     it('should perform search query with more results than one page', async () => {
       mock.clear({
         method: 'POST',
diff --git a/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.ts b/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.ts
index 5ec33a95e3..00c25905c3 100644
--- a/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.ts
+++ b/plugins/search-backend-module-elasticsearch/src/engines/ElasticSearchSearchEngine.ts
@@ -268,7 +268,7 @@ export class ElasticSearchSearchEngine implements SearchEngine {
         body: elasticSearchQuery,
       });
       const { page } = decodePageCursor(query.pageCursor);
-      const hasNextPage = result.body.hits.total.value > page * pageSize;
+      const hasNextPage = result.body.hits.total.value > (page + 1) * pageSize;
       const hasPreviousPage = page > 0;
       const nextPageCursor = hasNextPage
         ? encodePageCursor({ page: page + 1 })