EntityFramework用法探索（八）事务处理

使用 前文中描述的Retail示例 ，在Customer对象的Mapping中设置Name属性：
我们构造一个有效的Customer对象，再构造一个无效的Name属性为空的对象。

   DomainModels.Customer customer1 = new DomainModels.Customer()
        {
          Name = "Dennis Gao",
          Address = "Beijing",
          Phone = "",
        };
        DomainModels.Customer customer2 = new DomainModels.Customer()
        {
          //Name = "Degang Guo", // 创造一个无效的对象，此处客户名称不能为空
         Address = "Beijing",
         Phone = "",
       };

我们使用如下代码添加Customer对象数据到数据库中，

   Customer entity1 = Mapper.Map<DomainModels.Customer, Customer>(customer1);
        Customer entity2 = Mapper.Map<DomainModels.Customer, Customer>(customer2);

        using (RetailEntities context = new RetailEntities())
        {
          context.Customers.Add(entity1);
          context.Customers.Add(entity2);
          context.SaveChanges(); // 提交时将抛出异常

         customer1.Id = entity1.Id;
         customer2.Id = entity2.Id;
       }

       Console.WriteLine(customer1);
       Console.WriteLine(customer2);

EntityFramework已经明确的告诉我们某Entity验证失败。此时查询数据库，两条记录均不存在。EntityFramework自带的事务已经帮助回滚了操作。

现在我们修改下程序，改为提交两次：

  try
        {
          using (RetailEntities context = new RetailEntities())
          {
            context.Customers.Add(entity1);
            context.SaveChanges(); // 顺利执行
            context.Customers.Add(entity2);
            context.SaveChanges(); // 提交时将抛出异常

           customer1.Id = entity1.Id;
           customer2.Id = entity2.Id;
         }
       }
       catch (Exception ex)
       {
         Console.WriteLine(FlattenException(ex));
       }

然后我们修改代码，增加TransactionScope，

实例1

  using (var transactionScope = new TransactionScope(
            TransactionScopeOption.RequiresNew))
          {
            Customer entity1 = Mapper.Map<DomainModels.Customer, Customer>(customer1);
            Customer entity2 = Mapper.Map<DomainModels.Customer, Customer>(customer2);

            using (RetailEntities context = new RetailEntities())
            {
              context.Customers.Add(entity1);
             context.SaveChanges(); // 顺利提交
             context.Customers.Add(entity2);
             context.SaveChanges(); // 提交时将抛出异常

             customer1.Id = entity1.Id;
             customer2.Id = entity2.Id;
           }

           transactionScope.Complete();
         }
       }
       catch (Exception ex)
       {
         Console.WriteLine(FlattenException(ex));
       }

 实例2

   using (var transactionScope = new TransactionScope(TransactionScopeOption.RequiresNew))
                {

                    //收藏
                    string collSql = @"delete from CollectDiscoverInfo where DiscoverID='{0}'";

                    collSql = string.Format(collSql, id);
                    db.Database.ExecuteSqlCommand(collSql);

                    //评论
                    string commentSql = "delete from CommentDiscoverInfo where DiscoverID='{0}'";
                    commentSql = string.Format(commentSql, id);
                    db.Database.ExecuteSqlCommand(commentSql);

                    //赞
                    string praiseSql = "delete from PraiseDiscover where DiscoverID='{0}'";
                    praiseSql = string.Format(praiseSql, id);
                    db.Database.ExecuteSqlCommand(praiseSql);

                    //图片
                    string photoSql = "delete from DiscoverPhotoInfo where DiscoverID='{0}'";

                    photoSql = string.Format(photoSql, id);
                    db.Database.ExecuteSqlCommand(photoSql);

                    //话题
                    db.DiscoverInfo.Remove(entity);
                    db.SaveChanges();

                    //提交事务
                    transactionScope.Complete();
                }