EF 事物Transaction简单操作

/// <summary>
/// 申请提现
/// </summary>
/// <param name="userId">用户id</param>
/// <param name="amount">提现金额</param>
/// <returns></returns>
public int ApplyTakeCash(int userId, decimal amount)
{ 
    if(IsExistUser(userId)) return -3; //用户不存在
    using (var context = new MediaDBContext())
    {
        var channelUser = context.ChannelUsers.FirstOrDefault(c => c.UserId == userId);
        if (channelUser == null) return -3;//用户不存在
        var purse = context.BackPurses.FirstOrDefault(c => c.OwnerId == channelUser.LeaderId);
        if (purse == null) return -2; //未绑定银行卡
        if (purse.Balance < amount) return -1; //余额不足
        using (var trans = context.Database.BeginTransaction())
        {
            string description = string.Format("用户【{0}】申请提现【{1}】元金额", channelUser.User.Mobile, amount);
            try
            {
                var model = new BackWithdrawCash
                {
                    Amount = amount,
                    ApplicantId = 0,
                    PurseId = purse.Id,
                    Remark = description
                };
                //添加提现申请记录
                context.BackWithdrawCashs.Add(model);
                //减少提现额度
                purse.Balance = purse.Balance - amount;
                //提交
                int res = context.SaveChanges();
                if (res > 0)
                {
                    //添加日志
                    AddOperateRecord(userId, channelUser.LeaderId, description+"成功");
                    //提交事物
                    trans.Commit();
                    return 1; //提交成功
                }
                //添加日志
                AddOperateRecord(userId, channelUser.LeaderId, description + "失败");
                return 0;//提交失败
            }
            catch (Exception ex)
            {
                Logger.Error("【TradingServices[ApplyTakeCash]】", ex);
                //添加日志
                AddOperateRecord(userId, channelUser.LeaderId, string.Format("【{0}】【{1}】",description,ex.Message));
                //事物回滚
                trans.Rollback();
                return 0; //提交失败
            }
        }
    }
}