fix: added new field into purchase and stock cancelled or red flush

stock/models.py

@@ -133,6 +133,21 @@ class StockChangeRecord(ModelBase):
         self.details.count()
         return self.details.count()
 
+    @property
+    def is_offset(self) -> bool:
+        """是否为红冲记录（用于冲抵其他记录）"""
+        return self.stock_snapshots.filter(offset_to__isnull=False).exists()
+
+    @property
+    def is_reversed(self) -> bool:
+        """是否已被红冲"""
+        return self.stock_snapshots.filter(cancelled=True).exists()
+
+    @property
+    def cancelled(self) -> bool:
+        """兼容字段：是否已被红冲"""
+        return self.is_reversed
+
     @property
     def delta_num_of_rolls(self) -> int:
         """计算库存变动的匹数增减"""