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Co-authored-by: aider (openai/DeepSeek-V3.2-Thinking) <aider@aider.chat>

inventory-backend/app/services/bom_service.py

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+from app.extensions import db
+from app.models.bom import BomTable
+from app.models.base import MaterialBase
+from app.models.inbound.buy import StockBuy
+from sqlalchemy import func
+
+class BomService:
+    @staticmethod
+    def create_or_update_bom(parent_id, child_list):
+        """
+        保存/更新父件的BOM子件关系
+        child_list: [{"child_id": int, "dosage": float, "remark": str}, ...]
+        """
+        # 删除该父件原有的BOM记录
+        BomTable.query.filter_by(parent_id=parent_id).delete()
+        # 插入新的
+        for item in child_list:
+            bom = BomTable(
+                parent_id=parent_id,
+                child_id=item['child_id'],
+                dosage=item.get('dosage', 0),
+                remark=item.get('remark', '')
+            )
+            db.session.add(bom)
+        db.session.commit()
+        return True
+
+    @staticmethod
+    def get_bom_with_stock(parent_id):
+        """
+        查询父件的BOM结构及库存信息
+        """
+        bom_items = db.session.query(
+            BomTable,
+            MaterialBase.name.label('child_name')
+        ).join(
+            MaterialBase, BomTable.child_id == MaterialBase.id
+        ).filter(
+            BomTable.parent_id == parent_id
+        ).all()
+
+        result = []
+        for bom, child_name in bom_items:
+            # 查询该子件在 StockBuy 中的可用库存总量
+            stock_qty = db.session.query(
+                func.coalesce(func.sum(StockBuy.available_quantity), 0)
+            ).filter(
+                StockBuy.base_id == bom.child_id
+            ).scalar() or 0
+
+            # 计算最大可生产数量
+            dosage = float(bom.dosage) if bom.dosage else 0
+            max_producible = int(stock_qty // dosage) if dosage > 0 else 0
+
+            result.append({
+                'child_id': bom.child_id,
+                'child_name': child_name,
+                'dosage': dosage,
+                'current_stock': float(stock_qty),
+                'max_producible': max_producible,
+                'remark': bom.remark or ''
+            })
+        return result