perf: 修复 get_bom_with_stock_by_bom_no N+1 查询问题，改为批量 IN + 内存字典匹配

inventory-backend/app/services/bom_service.py

@@ -244,40 +244,46 @@ class BomService:
     @staticmethod
     def get_bom_with_stock_by_bom_no(bom_no):
         """
-        根据 bom_no 获取配方详情，并计算：
-        1. 总可用库存
-        2. 最大可生产套数
-        3. ★ 聚合库位信息 (warehouse_locations)
+        根据 bom_no 获取配方详情，并计算（已修复 N+1 性能问题）
         """
         detail = BomService.get_bom_detail(bom_no)
-        if not detail:
-            return None
+        if not detail or not detail.get('children'):
+            return detail
 
+        # 1. 提取所有子件的 ID 列表
+        child_ids = [child['child_id'] for child in detail['children']]
+
+        # 2. 用一条 IN 语句批量查出所有相关子件的库存和库位
+        stock_stats = db.session.query(
+            StockBuy.base_id,
+            func.coalesce(func.sum(StockBuy.available_quantity), 0).label('total_qty'),
+            func.string_agg(distinct(StockBuy.warehouse_location), ', ').label('locations')
+        ).filter(
+            StockBuy.base_id.in_(child_ids),
+            StockBuy.available_quantity > 0
+        ).group_by(
+            StockBuy.base_id
+        ).all()
+
+        # 3. 将查询结果转换为字典 (Map)，方便后续 O(1) 极速匹配
+        stock_map = {
+            stat.base_id: {
+                'qty': stat.total_qty,
+                'loc': stat.locations if stat.locations else ''
+            }
+            for stat in stock_stats
+        }
+
+        # 4. 遍历组装数据（纯内存操作，极快）
         for child in detail['children']:
-            # 1. 查询该子件的总库存
-            stock_qty = db.session.query(
-                func.coalesce(func.sum(StockBuy.available_quantity), 0)
-            ).filter(
-                StockBuy.base_id == child['child_id']
-            ).scalar() or 0
+            base_id = child['child_id']
+            stat = stock_map.get(base_id, {'qty': 0, 'loc': ''})
 
-            # 2. ★ 查询该子件涉及的所有库位，并去重拼接 (PostgreSQL 使用 string_agg)
-            # 注意：这里假设主要是 stock_buy 表，如果是成品或半成品也需要做类似 Union 查询
-            # 为简化，这里演示只查 stock_buy 的库位
-            locations = db.session.query(
-                # 去除空值和重复值
-                func.string_agg(distinct(StockBuy.warehouse_location), ', ')
-            ).filter(
-                StockBuy.base_id == child['child_id'],
-                StockBuy.available_quantity > 0,  # 只看有货的库位
-                StockBuy.warehouse_location != None,
-                StockBuy.warehouse_location != ''
-            ).scalar()
+            stock_qty = float(stat['qty'])
+            dosage = float(child['dosage']) if child.get('dosage') else 0
 
-            child['current_stock'] = float(stock_qty)
-            child['warehouse_location'] = locations or ''  # 返回给前端
-
-            dosage = child['dosage']
+            child['current_stock'] = stock_qty
+            child['warehouse_location'] = stat['loc']
             child['max_producible'] = int(stock_qty // dosage) if dosage > 0 else 0
 
         return detail