fix: rebuild stock change record

stock/models.py

@@ -2,6 +2,7 @@ from django.db import models
 from django.core.exceptions import ValidationError
 from flower.common import ModelBase
 from basic_info import models as basic_info_models
+from functools import reduce
 import decimal
 
 
@@ -48,12 +49,6 @@ class StockChangeRecord(ModelBase):
 
     id = models.BigAutoField(primary_key=True)
     type = models.IntegerField(choices=StockChangeTypeEnum.choices, verbose_name='变动类型')
-    product = models.ForeignKey(
-        basic_info_models.Product,
-        on_delete=models.PROTECT,
-        related_name='stock_change_records',
-        verbose_name='产品',
-    )
     warehouse = models.ForeignKey(
         basic_info_models.WareHouse,
         on_delete=models.PROTECT,
@@ -64,14 +59,6 @@ class StockChangeRecord(ModelBase):
         choices=StockChangeSourceEnum.choices, 
         verbose_name='变动来源',
     )
-    unit = models.IntegerField(
-        verbose_name='单位', 
-        choices=basic_info_models.ProductUnitEnum.choices,
-    )
-    num_of_rolls = models.IntegerField(
-        default=1,
-        verbose_name='匹数',
-    )
     created_by = models.ForeignKey(
         'auth.User',
         on_delete=models.PROTECT,
@@ -79,14 +66,13 @@ class StockChangeRecord(ModelBase):
         blank=True,
         verbose_name='操作人',
     )
-    quantity = models.DecimalField(max_digits=10, decimal_places=2, verbose_name='数量')
     source_id = models.BigIntegerField(null=True, blank=True, verbose_name='来源单据ID')
     is_finished = models.BooleanField(default=False, verbose_name='完成出入库')
     finished_at = models.DateTimeField(null=True, blank=True, verbose_name='完成时间')
     remarks = models.TextField(blank=True, null=True, verbose_name='备注')
 
     def __str__(self):
-        return f'出入库记录 {self.id} - 仓库：{self.warehouse.name} - 产品: {self.product.name}'
+        return f'出入库记录 {self.id} - 仓库：{self.warehouse.name}'
 
     class Meta:
         verbose_name = '出入库记录'
@@ -115,17 +101,57 @@ class StockChangeRecord(ModelBase):
         return self.type == StockChangeTypeEnum.REMOVE
 
     @property
-    def delta(self) -> decimal.Decimal:
-        """计算库存变动的数量增减"""
+    def num_of_rolls(self) -> int:
+        """获取匹数"""
+        self.details.count()
+        return self.details.count()
+
+    @property
+    def delta_num_of_rolls(self) -> int:
+        """计算库存变动的匹数增减"""
 
         # 入库为正，出库为负
         if self.type == StockChangeTypeEnum.ADD:
-            return self.quantity
+            return self.num_of_rolls
         elif self.type == StockChangeTypeEnum.REMOVE:
-            return -self.quantity
+            return self.num_of_rolls * -1
         else:
             raise ValueError("未知的库存变动类型")
 
+    
+class StockChangeDetail(ModelBase):
+    """库存变动明细模型"""
+
+    id = models.BigAutoField(primary_key=True)
+    product = models.ForeignKey(
+        basic_info_models.Product,
+        on_delete=models.PROTECT,
+        related_name='stock_change_details',
+        verbose_name='产品',
+    )
+    unit = models.IntegerField(
+        verbose_name='单位', 
+        choices=basic_info_models.ProductUnitEnum.choices,
+    )
+    stock_change_record = models.ForeignKey(
+        StockChangeRecord,
+        on_delete=models.CASCADE,
+        related_name='details',
+        verbose_name='库存变动记录',
+    )
+    quantity = models.DecimalField(max_digits=10, decimal_places=2, verbose_name='数量')
+    unit = models.IntegerField(
+        verbose_name='单位', 
+        choices=basic_info_models.ProductUnitEnum.choices,
+    )
+
+    def __str__(self):
+        return f'库存变动明细 {self.id} - 记录ID: {self.stock_change_record.id}'
+
+    class Meta:
+        verbose_name = '库存变动明细'
+        verbose_name_plural = '库存变动明细'
+
 
 class Inventory(ModelBase):
     """库存模型"""
@@ -217,7 +243,7 @@ class StockSnapshot(ModelBase):
     )
 
     def __str__(self):
-        return f'库存快照 {self.id} - 日期: {self.snapshot_date} - 产品: {self.product.name}'
+        return f'库存快照 {self.id} - 产品: {self.product.name}'
 
     class Meta:
         verbose_name = '库存快照'