修复bug

src/WMS.Web.Domain/Entitys/Box.cs

@@ -126,9 +126,10 @@ namespace WMS.Web.Domain.Entitys
                     MaterialId = materialId,
                     Qty = qty
                 });
-            }else
+            }
+            else
             {
-                d.Qty = d.Qty + qty;
+                d.Qty = qty;
             }
             return Result.ReSuccess();
         }
@@ -141,18 +142,9 @@ namespace WMS.Web.Domain.Entitys
         public Result BackRecordDown(int materialId, decimal qty)
         {
             var d = this.Details.FirstOrDefault(f => f.MaterialId == materialId);
-            if (d == null)
-            {
-                this.Details.Add(new BoxDetails()
-                {
-                    MaterialId = materialId,
-                    Qty = qty
-                });
-            }
-            else
-            {
-                d.Qty = d.Qty + qty;
-            }
+            if (d != null)
+                d.Qty = (d.Qty - qty) > 0 ? (d.Qty - qty) : 0;
+
             return Result.ReSuccess();
         }
     }