用户商品关联表删除，直接用商品表记录用户id

ch-dao/src/main/java/com/wwdz/ch/db/impl/ItemDaoImpl.java

@@ -437,6 +437,9 @@ public class ItemDaoImpl implements ItemDao {
 
     private List<UserItemsRelation> convertList(List<Item> items) {
         List<UserItemsRelation> list = new ArrayList<>();
+        if (CollectionUtils.isEmpty(items)) {
+            return list;
+        }
         items.forEach(item -> {
             UserItemsRelation userItemsRelation = new UserItemsRelation();
             userItemsRelation.setItemId(item.getId());
@@ -447,6 +450,9 @@ public class ItemDaoImpl implements ItemDao {
     }
 
     private UserItemsRelation convert(Item item) {
+        if (ObjectUtils.isEmpty(item)) {
+            return null;
+        }
         UserItemsRelation userItemsRelation = new UserItemsRelation();
         userItemsRelation.setItemId(item.getId());
         userItemsRelation.setUserId(item.getUserId());