fix: consider nulls first | last on orderBy (#1064)

fix #1062

Author: patricebender

db-service/lib/cqn2sql.js

@@ -421,14 +421,15 @@ class CQN2SQLRenderer {
    * @returns {string[] | string} SQL
    */
   orderBy(orderBy, localized) {
-    return orderBy.map(
-      localized
-        ? c =>
-          this.expr(c) +
+    return orderBy.map(c => {
+      const o = localized
+        ? this.expr(c) +
           (c.element?.[this.class._localized] ? ' COLLATE NOCASE' : '') +
           (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC')
-        : c => this.expr(c) + (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC'),
-    )
+        : this.expr(c) + (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC')
+      if (c.nulls) return o + ' NULLS ' + (c.nulls.toLowerCase() === 'first' ? 'FIRST' : 'LAST')
+      return o
+    })
   }
 
   /**

hana/lib/HANAService.js

@@ -904,17 +904,17 @@ SELECT ${mixing} FROM JSON_TABLE(SRC.JSON, '$' COLUMNS(${extraction})) AS NEW LE
     }
 
     orderBy(orderBy, localized) {
-      return orderBy.map(
-        localized
-          ? c =>
-            this.expr(c) +
+      return orderBy.map(c => {
+        const o = localized
+          ? this.expr(c) +
             (c.element?.[this.class._localized]
-              ? ` COLLATE ${collations[this.context.locale] || collations[this.context.locale.split('_')[0]] || collations['']
-              }`
+              ? ` COLLATE ${collations[this.context.locale] || collations[this.context.locale.split('_')[0]] || collations['']}`
               : '') +
             (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC')
-          : c => this.expr(c) + (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC'),
-      )
+          : this.expr(c) + (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC')
+        if (c.nulls) return o + ' NULLS ' + (c.nulls.toLowerCase() === 'first' ? 'FIRST' : 'LAST')
+        return o
+      })
     }
 
     limit({ rows, offset }) {

postgres/lib/PostgresService.js

@@ -344,14 +344,15 @@ GROUP BY k
 
   static CQN2SQL = class CQN2Postgres extends SQLService.CQN2SQL {
     _orderBy(orderBy, localized, locale) {
-      return orderBy.map(
-        localized
-          ? c =>
-            this.expr(c) +
+      return orderBy.map(c => {
+        const nulls = c.nulls || (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? 'LAST' : 'FIRST')
+        const o = localized
+          ? this.expr(c) +
             (c.element?.[this.class._localized] ? ` COLLATE "${locale}"` : '') +
-            (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC NULLS LAST' : ' ASC NULLS FIRST')
-          : c => this.expr(c) + (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC NULLS LAST' : ' ASC NULLS FIRST'),
-      )
+            (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC')
+          : this.expr(c) + (c.sort?.toLowerCase() === 'desc' || c.sort === -1 ? ' DESC' : ' ASC')
+        return o + ' NULLS ' + (nulls.toLowerCase() === 'first' ? 'FIRST' : 'LAST')
+      })
     }
 
     orderBy(orderBy) {

test/scenarios/bookshop/orderBy.test.js

@@ -66,4 +66,13 @@ describe('Bookshop - Order By', () => {
     expect(res.length).to.be.eq(1)
     expect(res[0].author).to.eq('Charlotte Brontë')
   })
+
+  test('nulls first | last', async () => {
+    const { Authors } = cds.entities('sap.capire.bookshop')
+    await INSERT.into(Authors).entries({ ID: 42, name: 'Brandon Sanderson' }) // dateOfDeath => null
+    const nullsFirst = await cds.ql`SELECT from ${Authors} { name } order by dateOfDeath asc nulls first`
+    expect(nullsFirst[0].name).to.eq('Brandon Sanderson')
+    const nullsLast = await cds.ql`SELECT from ${Authors} { name } order by dateOfDeath asc nulls last`
+    expect(nullsLast.at(-1).name).to.eq('Brandon Sanderson')
+  });
 })