feat: salesitem delete guard service

shipment/services.py

@@ -32,6 +32,24 @@ def _resolve_user_employee(user):
     return getattr(user, "employee", None)
 
 
+def get_active_sales_items_queryset() -> QuerySet[SalesItem]:
+    """
+    返回未软删除的销售品查询集。
+    """
+    return SalesItem.objects.filter(delete_at__isnull=True)
+
+
+def ensure_sales_item_can_be_soft_deleted(sales_item: SalesItem) -> None:
+    """
+    校验销售品是否允许软删除。
+
+    当前规则：
+    - 已关联出货单的销售品不允许删除
+    """
+    if sales_item.shipment_id is not None:
+        raise ValueError("已关联出货单的销售品不允许删除")
+
+
 def _resolve_delivery_shipments(
     *,
     shipment_ids: list[int],
@@ -81,10 +99,9 @@ def get_customers_with_unshipped_sales_items(*, merchant) -> QuerySet:
     """
     from basic_info.models import Customer
 
-    base_sales_items = SalesItem.objects.filter(
+    base_sales_items = get_active_sales_items_queryset().filter(
         merchant=merchant,
         shipment__isnull=True,
-        delete_at__isnull=True,
         customer_id=OuterRef("pk"),
     )
     count_subquery = (
@@ -155,8 +172,9 @@ def get_sales_items_by_printing_order(
     ).values_list("id", flat=True)
 
     # 2. 查询 SalesItem，过滤 printing_job_id 在这些 job_ids 中
-    queryset = SalesItem.objects.filter(printing_job_id__in=list(job_ids))
-    queryset = queryset.filter(delete_at__isnull=True)
+    queryset = get_active_sales_items_queryset().filter(
+        printing_job_id__in=list(job_ids)
+    )
 
     # 3. 根据参数决定是否过滤已出货的销售品
     if not include_already_has_shipment:
@@ -177,10 +195,9 @@ def get_sales_items_by_customer(
 
     仅返回当前商户下、customer_id 匹配的销售品。
     """
-    queryset = SalesItem.objects.filter(
+    queryset = get_active_sales_items_queryset().filter(
         merchant=merchant,
         customer_id=customer_id,
-        delete_at__isnull=True,
     )
 
     if external_order_id:
@@ -277,6 +294,8 @@ def delete_sales_item(
     if sales_item.delete_at is not None:
         return sales_item
 
+    ensure_sales_item_can_be_soft_deleted(sales_item)
+
     sales_item.delete_at = timezone.now()
     sales_item.delete_by = deleted_by
     sales_item.save(update_fields=["delete_at", "delete_by", "updated_at"])
@@ -669,7 +688,7 @@ def create_shipment(
         from printing.models import PrintingJob
 
         # 查询销售品
-        sales_items = SalesItem.objects.filter(id__in=sales_item_ids, delete_at__isnull=True)
+        sales_items = get_active_sales_items_queryset().filter(id__in=sales_item_ids)
         found_ids = set(sales_items.values_list("id", flat=True))
         missing_ids = set(sales_item_ids) - found_ids
 
@@ -731,8 +750,8 @@ def create_shipment(
 
     # 关联销售品
     if sales_item_ids:
-        updated = SalesItem.objects.filter(
-            id__in=sales_item_ids, merchant=merchant, delete_at__isnull=True
+        updated = get_active_sales_items_queryset().filter(
+            id__in=sales_item_ids, merchant=merchant
         ).update(shipment=shipment)
         if updated != len(sales_item_ids):
             raise ValueError("存在不属于当前商户的销售品，无法关联到出货单")