wip: nullability for unmanaged paths

db-service/lib/assert-constraint.js

@@ -62,13 +62,15 @@ function attachConstraints(_results, req) {
       const xpr = []
       // if the element is nullable, we prepend xpr with `<element> IS NULL OR …`
       if (!element.notNull && !element.on) {
+        // if(element.on) --> REVISIT: HANA doesnt like this, what can we do to ensure nullability?
+        //   xpr.unshift({ ...coalesce(condition.xpr) }, 'or')
         xpr.unshift({ ref: [element.name] }, 'is', 'null', 'or')
       }
       xpr.push({ xpr: condition.xpr })
       return {
         // case … when … needed for hana compatibility
         // REVISIT: can we move workaround to HANAService only?
-        xpr: ['case', 'when', { xpr }, 'then', { val: true }, 'else', { val: false }, 'end'],
+        xpr: wrapInCaseWhen(xpr),
         as: name,
         cast: {
           type: 'cds.Boolean',
@@ -139,6 +141,9 @@ function attachConstraints(_results, req) {
   function wrapInCaseWhen(xpr) {
     return ['case', 'when', { xpr }, 'then', { val: true }, 'else', { val: false }, 'end']
   }
+  function coalesce(xpr) {
+    return { func: 'coalesce', args: [{ xpr }, { val: true }] }
+  }
 }
 
 async function checkConstraints(req) {

test/bookshop/db/schema.cds

@@ -17,15 +17,8 @@ entity Books : managed {
         message: 'The stock must be greater than or equal to 0',
         parameters: []     // to be inserted into the message
       } 
-      // @assert.constraint : {
-      //   condition: ( stock <= price ),
-      //   message: 'The stock must be less than or equal to price',
-      //   parameters: []     // to be inserted into the message
-      // } 
       stock          : Integer;
       price          : Decimal;
-      // one of the tests inserts a very big decimal which
-      // collides with our constraint above :D
       dummyDecimal   : Decimal;
       currency       : Currency;
       image          : LargeBinary @Core.MediaType: 'image/png';
@@ -55,9 +48,10 @@ entity Authors : managed {
 /** Hierarchically organized Code List for Genres */
 entity Genres : sap.common.CodeList {
   key ID       : Integer;
+      @assert.constraint: ( parent.name is not null)
       parent   : Association to Genres;
       // make sure only our pre-defined genres are allowed
-      @assert.constraint: ( children.name in (
+      @assert.constraint: ( ( children.ID is null ) or children.name in (
         'Fiction', 'Drama', 'Poetry', 'Fantasy', 'Science Fiction',
         'Romance', 'Mystery', 'Thriller', 'Dystopia', 'Fairy Tale',
         'Non-Fiction', 'Biography', 'Autobiography', 'Essay', 'Speech',

test/scenarios/bookshop/assert-constraint.test.js

@@ -116,5 +116,14 @@ describe('Bookshop - assertions', () => {
       // both should have been created
       expect(genres).to.have.length(2)
     })
+
+    test('genre without children works', async () => {
+      await POST('admin/Genres', {
+        ID: 102,
+        name: 'Genre without children',
+      }, { auth: { username: 'alice' } })
+      const genre = await SELECT.one.from(Genres).where({ ID: 102 })
+      expect(genre).to.exist
+    })
   })
 })