From dd48068b099d1b8eafef1dd3565b2685cf0cf103 Mon Sep 17 00:00:00 2001
From: Elbarae Rguig <elbarae1921@gmail.com>
Date: Mon, 22 Aug 2022 14:46:23 +0100
Subject: [PATCH] fix: only add NULL_SORT when the nullSort field is provided,
 and add more tests (#297)

---
 README.md            |  7 ++++---
 src/paginate.spec.ts | 42 +++++++++++++++++++++++++++++++++++++++---
 src/paginate.ts      |  5 ++++-
 3 files changed, 47 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index b557f6f..de27a29 100644
--- a/README.md
+++ b/README.md
@@ -155,12 +155,13 @@ const paginateConfig: PaginateConfig<CatEntity> {
    * Description: These are the columns that are valid to be sorted by.
    */
   sortableColumns: ['id', 'name', 'color'],
-  
+
   /**
    * Required: false
    * Type: 'first' | 'last'
-   * Default: 'last'
-   * Description: Define whether to put null values at the beginning or end of the result set.
+   * Default: 'first'
+   * Description: (ONLY WORKS WITH POSTGRES) Define whether to put null values
+   * at the beginning or end of the result set.
    */
   nullSort: 'last',
 
diff --git a/src/paginate.spec.ts b/src/paginate.spec.ts
index 65cf44e..c6d80a9 100644
--- a/src/paginate.spec.ts
+++ b/src/paginate.spec.ts
@@ -200,7 +200,24 @@ describe('paginate', () => {
         const config: PaginateConfig<CatEntity> = {
             sortableColumns: ['age', 'createdAt'],
             nullSort: 'last',
-            defaultSortBy: [['age', 'DESC']],
+            defaultSortBy: [['age', 'ASC']],
+        }
+        const query: PaginateQuery = {
+            path: '',
+        }
+
+        const result = await paginate<CatEntity>(query, catRepo, config)
+        const expectedResult = [...cats.slice(0, -1).reverse(), cats.slice(-1)[0]]
+
+        expect(result.meta.sortBy).toStrictEqual([['age', 'ASC']])
+        expect(result.data).toStrictEqual(expectedResult)
+    })
+
+    it('should put null values first when sorting', async () => {
+        const config: PaginateConfig<CatEntity> = {
+            sortableColumns: ['age', 'createdAt'],
+            nullSort: 'first',
+            defaultSortBy: [['age', 'ASC']],
         }
         const query: PaginateQuery = {
             path: '',
@@ -208,8 +225,27 @@ describe('paginate', () => {
 
         const result = await paginate<CatEntity>(query, catRepo, config)
 
-        expect(result.meta.sortBy).toStrictEqual([['age', 'DESC']])
-        expect(result.data).toStrictEqual(cats)
+        const expectedResult = [cats[cats.length - 1], ...cats.slice(0, cats.length - 1).reverse()]
+
+        expect(result.meta.sortBy).toStrictEqual([['age', 'ASC']])
+        expect(result.data).toStrictEqual(expectedResult)
+    })
+
+    it('should put null values first when nullSort is not specified', async () => {
+        const config: PaginateConfig<CatEntity> = {
+            sortableColumns: ['age', 'createdAt'],
+            defaultSortBy: [['age', 'ASC']],
+        }
+        const query: PaginateQuery = {
+            path: '',
+        }
+
+        const result = await paginate<CatEntity>(query, catRepo, config)
+
+        const expectedCats = cats.slice()
+
+        expect(result.meta.sortBy).toStrictEqual([['age', 'ASC']])
+        expect(result.data).toStrictEqual(expectedCats.reverse())
     })
 
     it('should sort result by multiple columns', async () => {
diff --git a/src/paginate.ts b/src/paginate.ts
index e15b16d..f81030d 100644
--- a/src/paginate.ts
+++ b/src/paginate.ts
@@ -173,7 +173,10 @@ export async function paginate<T>(
 
     if (config.sortableColumns.length < 1) throw new ServiceUnavailableException()
 
-    const NULL_SORT = config.nullSort === 'last' ? 'NULLS LAST' : 'NULLS FIRST'
+    let NULL_SORT: 'NULLS LAST' | 'NULLS FIRST'
+    if (config.nullSort) {
+        NULL_SORT = config.nullSort === 'last' ? 'NULLS LAST' : 'NULLS FIRST'
+    }
 
     if (query.sortBy) {
         for (const order of query.sortBy) {