fix: null sort (#1089)

Author: vsamofal

.nvmrc

@@ -0,0 +1 @@
+v20

src/helper.ts

@@ -347,3 +347,7 @@ export function isDateColumnType(type: any): boolean {
     ]
     return dateTypes.includes(type)
 }
+
+export function quoteVirtualColumn(columnName: string, isMySqlOrMariaDb: boolean): string {
+    return isMySqlOrMariaDb ? `\`${columnName}\`` : `"${columnName}"`
+}

src/paginate.spec.ts

@@ -876,6 +876,33 @@ describe('paginate', () => {
         expect(result.links.current).toBe('?page=1&limit=20&sortBy=cat.id:DESC')
     })
 
+    it('should handle nullSort with relations properly', async () => {
+        const config: PaginateConfig<CatEntity> = {
+            sortableColumns: ['id', 'age'],
+            nullSort: 'last',
+            defaultSortBy: [['age', 'ASC']],
+            relations: ['toys'],
+        }
+        const query: PaginateQuery = {
+            path: '',
+        }
+
+        const result = await paginate<CatEntity>(query, catRepo, config)
+
+        // Prepare expected result - cats ordered by age with null age last, including toys relation
+        const expectedResult = [...cats]
+            .sort((a, b) => {
+                if (a.age === null && b.age === null) return 0
+                if (a.age === null) return 1
+                if (b.age === null) return -1
+                return a.age - b.age
+            })
+            .map((cat) => cat.id)
+
+        expect(result.meta.sortBy).toStrictEqual([['age', 'ASC']])
+        expect(result.data.map((v) => v.id)).toStrictEqual(expectedResult)
+    })
+
     it('should return result based on sort and search on many-to-one relation', async () => {
         const config: PaginateConfig<CatToyEntity> = {
             relations: ['cat'],

src/paginate.ts

@@ -34,6 +34,7 @@ import {
     mergeRelationSchema,
     Order,
     positiveNumberOrDefault,
+    quoteVirtualColumn,
     RelationSchema,
     RelationSchemaInput,
     SortBy,
@@ -688,18 +689,18 @@ export async function paginate<T extends ObjectLiteral>(
             const isEmbedded = checkIsEmbedded(queryBuilder, columnProperties.propertyPath)
             let alias = fixColumnAlias(columnProperties, queryBuilder.alias, isRelation, isVirtualProperty, isEmbedded)
 
+            if (isVirtualProperty) {
+                alias = quoteVirtualColumn(alias, isMySqlOrMariaDb)
+            }
+
             if (isMySqlOrMariaDb) {
-                if (isVirtualProperty) {
-                    alias = `\`${alias}\``
-                }
                 if (nullSort) {
-                    queryBuilder.addOrderBy(`${alias} ${nullSort}`)
+                    const selectionAliasName = `${alias.replace(/\./g, '_')}IsNull`
+                    queryBuilder.addSelect(`${alias} ${nullSort}`, selectionAliasName)
+                    queryBuilder.addOrderBy(selectionAliasName)
                 }
                 queryBuilder.addOrderBy(alias, order[1])
             } else {
-                if (isVirtualProperty) {
-                    alias = `"${alias}"`
-                }
                 queryBuilder.addOrderBy(alias, order[1], nullSort as 'NULLS FIRST' | 'NULLS LAST' | undefined)
             }
         }