fix: createManyAndReturn doesn't work for polymorphic models

packages/runtime/src/enhancements/delegate.ts

@@ -367,9 +367,46 @@ export class DelegateProxyHandler extends DefaultPrismaProxyHandler {
                     return this.doCreate(tx, this.model, { data: item });
                 })
             );
+            return { count: r.length };
+        });
+    }
+
+    override createManyAndReturn(args: { data: any; select?: any; skipDuplicates?: boolean }): Promise<unknown[]> {
+        if (!args) {
+            throw prismaClientValidationError(this.prisma, this.options.prismaModule, 'query argument is required');
+        }
+        if (!args.data) {
+            throw prismaClientValidationError(
+                this.prisma,
+                this.options.prismaModule,
+                'data field is required in query argument'
+            );
+        }
+
+        if (!this.involvesDelegateModel(this.model)) {
+            return super.createManyAndReturn(args);
+        }
 
-            // filter out undefined value (due to skipping duplicates)
-            return { count: r.filter((item) => !!item).length };
+        if (this.isDelegateOrDescendantOfDelegate(this.model) && args.skipDuplicates) {
+            throw prismaClientValidationError(
+                this.prisma,
+                this.options.prismaModule,
+                '`createManyAndReturn` with `skipDuplicates` set to true is not supported for delegated models'
+            );
+        }
+
+        // `createManyAndReturn` doesn't support nested create, which is needed for creating entities
+        // inheriting a delegate base, so we need to convert it to a regular `create` here.
+        // Note that the main difference is `create` doesn't support `skipDuplicates` as
+        // `createManyAndReturn` does.
+
+        return this.queryUtils.transaction(this.prisma, async (tx) => {
+            const r = await Promise.all(
+                enumerate(args.data).map(async (item) => {
+                    return this.doCreate(tx, this.model, { data: item, select: args.select });
+                })
+            );
+            return r;
         });
     }
 

packages/runtime/src/enhancements/policy/handler.ts

@@ -461,7 +461,7 @@ export class PolicyProxyHandler<DbClient extends DbClientContract> implements Pr
         });
     }
 
-    createManyAndReturn(args: { select: any; include: any; data: any; skipDuplicates?: boolean }) {
+    createManyAndReturn(args: { data: any; select?: any; skipDuplicates?: boolean }) {
         if (!args) {
             throw prismaClientValidationError(this.prisma, this.prismaModule, 'query argument is required');
         }

packages/runtime/src/enhancements/proxy.ts

@@ -35,7 +35,7 @@ export interface PrismaProxyHandler {
 
     createMany(args: { data: any; skipDuplicates?: boolean }): Promise<BatchResult>;
 
-    createManyAndReturn(args: { data: any; select: any; include: any; skipDuplicates?: boolean }): Promise<unknown[]>;
+    createManyAndReturn(args: { data: any; select?: any; skipDuplicates?: boolean }): Promise<unknown[]>;
 
     update(args: any): Promise<unknown>;
 
@@ -124,7 +124,7 @@ export class DefaultPrismaProxyHandler implements PrismaProxyHandler {
         return this.deferred<{ count: number }>('createMany', args, false);
     }
 
-    createManyAndReturn(args: { data: any; select: any; include: any; skipDuplicates?: boolean }) {
+    createManyAndReturn(args: { data: any; select?: any; skipDuplicates?: boolean }) {
         return this.deferred<unknown[]>('createManyAndReturn', args);
     }
 

tests/integration/tests/enhancements/with-delegate/enhanced-client.test.ts

@@ -129,14 +129,44 @@ describe('Polymorphism Test', () => {
             db.ratedVideo.createMany({ data: { viewCount: 1, duration: 100, url: 'xyz', rating: 100 } })
         ).resolves.toMatchObject({ count: 1 });
 
+        await expect(
+            db.ratedVideo.createManyAndReturn({ data: { viewCount: 1, duration: 100, url: 'xyz', rating: 100 } })
+        ).resolves.toEqual(
+            expect.arrayContaining([
+                expect.objectContaining({
+                    assetType: 'Video',
+                    videoType: 'RatedVideo',
+                    viewCount: 1,
+                    duration: 100,
+                    url: 'xyz',
+                    rating: 100,
+                }),
+            ])
+        );
+
         await expect(
             db.ratedVideo.createMany({
                 data: [
                     { viewCount: 2, duration: 200, url: 'xyz', rating: 100 },
-                    { viewCount: 3, duration: 300, url: 'xyz', rating: 100 },
+                    { viewCount: 3, duration: 300, url: 'xyz', rating: 200 },
                 ],
             })
         ).resolves.toMatchObject({ count: 2 });
+
+        await expect(
+            db.ratedVideo.createManyAndReturn({
+                data: [
+                    { viewCount: 2, duration: 200, url: 'xyz', rating: 100 },
+                    { viewCount: 3, duration: 300, url: 'xyz', rating: 200 },
+                ],
+                select: { videoType: true, viewCount: true, rating: true },
+            })
+        ).resolves.toEqual(
+            expect.arrayContaining([
+                { videoType: 'RatedVideo', viewCount: 2, rating: 100 },
+                { videoType: 'RatedVideo', viewCount: 3, rating: 200 },
+            ])
+        );
     });
 
     it('create many polymorphic relation', async () => {

tests/regression/tests/issue-1576.test.ts

@@ -0,0 +1,63 @@
+import { loadSchema } from '@zenstackhq/testtools';
+describe('issue 1576', () => {
+    it('regression', async () => {
+        const { enhance } = await loadSchema(
+            `
+model Profile {
+  id Int @id @default(autoincrement())
+  name String
+  items Item[]
+  type String
+  @@delegate(type)
+  @@allow('all', true)
+}
+
+model GoldProfile extends Profile {
+  ticket Int
+}
+
+model Item {
+  id Int @id @default(autoincrement())
+  profileId Int
+  profile Profile @relation(fields: [profileId], references: [id])
+  type String
+  @@delegate(type)
+  @@allow('all', true)
+}
+
+model GoldItem extends Item {
+  inventory Boolean
+}
+          `
+        );
+
+        const db = enhance();
+
+        const profile = await db.goldProfile.create({
+            data: {
+                name: 'hello',
+                ticket: 5,
+            },
+        });
+
+        await expect(
+            db.goldItem.createManyAndReturn({
+                data: [
+                    {
+                        profileId: profile.id,
+                        inventory: true,
+                    },
+                    {
+                        profileId: profile.id,
+                        inventory: true,
+                    },
+                ],
+            })
+        ).resolves.toEqual(
+            expect.arrayContaining([
+                expect.objectContaining({ profileId: profile.id, type: 'GoldItem', inventory: true }),
+                expect.objectContaining({ profileId: profile.id, type: 'GoldItem', inventory: true }),
+            ])
+        );
+    });
+});