fix: deal with payload field value with undefined

packages/runtime/src/enhancements/nested-write-visitor.ts

@@ -323,12 +323,14 @@ export class NestedWriteVisitor {
             }
 
             if (fieldInfo.isDataModel) {
-                // recurse into nested payloads
-                for (const [subAction, subData] of Object.entries<any>(payload[field])) {
-                    if (this.isPrismaWriteAction(subAction) && subData) {
-                        await this.doVisit(fieldInfo.type, subAction, subData, payload[field], fieldInfo, [
-                            ...nestingPath,
-                        ]);
+                if (payload[field]) {
+                    // recurse into nested payloads
+                    for (const [subAction, subData] of Object.entries<any>(payload[field])) {
+                        if (this.isPrismaWriteAction(subAction) && subData) {
+                            await this.doVisit(fieldInfo.type, subAction, subData, payload[field], fieldInfo, [
+                                ...nestingPath,
+                            ]);
+                        }
                     }
                 }
             } else {

packages/runtime/src/enhancements/policy/policy-utils.ts

@@ -466,8 +466,10 @@ export class PolicyUtil {
                 ) {
                     // multi-field unique constraint, flatten it
                     delete args[field];
-                    for (const [f, v] of Object.entries(value)) {
-                        args[f] = v;
+                    if (value) {
+                        for (const [f, v] of Object.entries(value)) {
+                            args[f] = v;
+                        }
                     }
                 }
             }

tests/integration/tests/regression/issue-765.test.ts

@@ -0,0 +1,37 @@
+import { loadSchema } from '@zenstackhq/testtools';
+
+describe('Regression: issue 765', () => {
+    it('regression', async () => {
+        const { enhance } = await loadSchema(
+            `
+            model User {
+                id    Int     @id @default(autoincrement())
+                name  String
+
+                post   Post? @relation(fields: [postId], references: [id])
+                postId Int?
+
+                @@allow('all', true)
+              }
+
+            model Post {
+                id    Int    @id @default(autoincrement())
+                title String
+                User  User[]
+
+                @@allow('all', true)
+            }
+            `
+        );
+
+        const db = enhance();
+        const r = await db.user.create({
+            data: {
+                name: 'Me',
+                post: undefined,
+            },
+        });
+        expect(r.name).toBe('Me');
+        expect(r.post).toBeUndefined();
+    });
+});