Question

我想检查lastlogindate列是否为null。如果它不为null我想将对象转换为日期时间格式，否则我想使用条件运算符或linq返回为null。

公共类UserBase { public string UserName {get;组; }

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string Email { get; set; }

    public string PhoneNo { get; set; }

    public string MobilePhone { get; set; }

    public string GroupName { get; set; }

    public DateTime LastLogOnDate { get; set; }

    public string Active { get; set; }

    public string PlantId { get; set; }

    public string UserId { get; set; }
}

以上是我的课程和方法

user = datatable.AsEnumerable().Select(row =>
                    new EGDataStructure.UserBase
                    {
                        UserName = row.Field<string>("User Name"),
                        FirstName = row.Field<string>("First Name"),
                        LastName = row.Field<string>("Last Name"),
                        Email = row.Field<string>("Email ID"),
                        PhoneNo = row.Field<string>("Phone No"),
                        MobilePhone = row.Field<string>("Mobile No"),
                        GroupName = row.Field<string>("Group Name"),
                        LastLoginDate=row.Field<DateTime>("Last Logged Date")
                       LastLogOnDate =  if ( LastLoginDate != DBNull.Value)??Convert.ToDateTime(row.Field<DateTime>("Last Logged Date"),CultureInfo.InvariantCulture):Null,

                        Active = row.Field<string>("active"),
                        UserId = row.Field<string>("userId")
                    }).ToList();
                }

Answer 1

DateTime是一种结构，因此您需要Nullable<DateTime>（或缩写DateTime?）。

public DateTime? LastLogOnDate { get; set; }

和

LastLogOnDate = row.Field<DateTime?>("Last Logged Date")

如果您想明确区分null和其他值，例如因为该字段最初是字符串并需要转换：

LastLogOnDate = row.IsNull("Last Logged Date")
    ? (DateTime?)null
    : Convert.ToDateTime(row.Field<string>("Last Logged Date"), CultureInfo.InvariantCulture))

如何处理数据表列值

1 个答案: