Go-将NULL解析为time.Time in Struct

I am casting to a struct which has a time.Time type in.

t2 := time.Now()
format := "2006-01-02 15:04:05"

theTime, _ := time.Parse(format, t2.Format(format))

However, sometimes I don't want to set the time.Time field, how do you define this with the go/mysql db driver?

app_history := &models.AppsHistoryInsert{
    AppId:          response.SetAppData[0].Id,
    LiveDate:       &theTime,
}

Basically, I want

if(x == true) { 
    include time 
}
else {
    don't include time. 
}

I tried doing an if around the struct declaration itself and leaving the LiveDate field out but I got the error of controllers/apps.go:1068: undefined: app_history

you need to define the app_history variable outside the if statement and then assign to it in each of the branches

like so

var app_history &models.AppsHistoryInsert{}

if x {
  app_history = &models.AppsHistoryInsert{
    AppId:          response.SetAppData[0].Id,
    LiveDate:       &theTime,
  }
}else {
  app_history = &models.AppsHistoryInsert{
    AppId:          response.SetAppData[0].Id,
  }
}