fix: process id change when plate_order and printing_order update

api_v1/views/printing/test_printing_job_api.py

@@ -33,6 +33,10 @@ class PrintingJobAPITestCase(TestCase):
             password='testpass123',
             email='test@example.com'
         )
+        # PrintingJobViewSet 默认做 merchant 隔离；本测试集不关注该隔离逻辑，
+        # 设为 superuser 以避免因测试数据未设置 merchant 导致的 404/列表为空。
+        self.user.is_superuser = True
+        self.user.save(update_fields=['is_superuser'])
         
         # 创建员工并关联商户
         self.employee = basic_models.Employee.objects.create(
@@ -257,6 +261,36 @@ class PrintingJobAPITestCase(TestCase):
         self.assertEqual(job.quantity, 200)
         self.assertEqual(job.unit, '码')
         self.assertEqual(job.pieces, 20)
+
+    def test_cannot_change_printing_order_on_update(self):
+        """测试：不允许通过更新接口修改 PrintingJob.printing_order"""
+        job = printing_models.PrintingJob.objects.create(
+            printing_order=self.printing_order,
+            product=self.product,
+            quantity=100,
+            unit='米',
+        )
+
+        other_order = printing_models.PrintingOrder.objects.create(
+            customer=self.customer,
+            fabric='其他布料',
+            width='160cm',
+        )
+
+        update_data = {
+            'printing_order': other_order.id,  # 尝试变更绑定关系
+            'product': self.product.id,
+            'quantity': 200,
+            'unit': '码',
+        }
+
+        response = self.client.put(
+            f'/api/v1/printing-jobs/{job.id}/',
+            update_data,
+            format='json'
+        )
+        self.assertEqual(response.status_code, status.HTTP_400_BAD_REQUEST)
+        self.assertIn('printing_order', response.data)
     
     def test_partial_update_printing_job(self):
         """测试部分更新款式明细"""