使用 GORM 在 MySQL 中获取 NULL 日期时间值

我想获取最后一个 Visit_details 行，其 out_time 为NULL使用戈尔姆。NIL本身是一种类型，其中 VisitDetail OutTime 是mysql.NullTime.

Code:-

var visitDetail models.VisitDetail
db.Where("out_time=? ", nil).Last(&visitDetail)

//model VisitDetails
type VisitDetail struct {
    Id              int
    Visitor         Visitor  `gorm:"foreignkey:ClientId;association_foreignkey:Id"`
    VisitorId       int      `gorm:"not null;"`
    Location        Location `gorm:"foreignkey:LocationId;association_foreignkey:Id"`
    LocationId      int      `gorm:"not null;"`
    Purpose         string
    InTime          time.Time `gorm:"not null;"`
    OutTime         mysql.NullTime
    User            User `gorm:"foreignkey:ClientId;association_foreignkey:Id"`
    UserId          int  `gorm:"not null;"`
    Status          int  `gorm:"not null;"`
    ApproveByClient int  `gorm:"not null;"`
}

Query:-

select * from visit_details where out_time is NULL order by id desc limit 1;
+----+------------+-------------+---------+---------------------+----------+---------+--------+-------------------+
| id | visitor_id | location_id | purpose | in_time             | out_time | user_id | status | approve_by_client |
+----+------------+-------------+---------+---------------------+----------+---------+--------+-------------------+
| 20 |          1 |           8 |         | 2018-02-20 17:13:25 | NULL     |    1609 |      0 |                 0 |
+----+------------+-------------+---------+---------------------+----------+---------+--------+-------------------+
1 row in set (0.04 sec)

您可以将 OutTime 设置为指针，以便它可以为空。正如在doc http://gorm.io/docs/conventions.html#gorm-Model:

type YourStruct struct {
     OutTime *time.Time
}

然后运行您的查询

db.Where("out_time = ?", nil).Last(&visitDetail)