英文:
How to set the value of a field of type time.Time as time.Now() using reflect in Golang
问题
我有一个类型为test的结构体：
type test struct {
fname string
time time.Time
}
我想要使用reflect包将字段"time"的值设置为time.Now()。
我正在创建一个类似下面这样的函数：
func setRequestParam(arg interface{}, param string, value interface{}) {
v := reflect.ValueOf(arg).Elem()
f := v.FieldByName(param)
if f.IsValid() {
if f.CanSet() {
if f.Kind() == reflect.String {
f.SetString(value.(string))
return
} else if f.Kind() == reflect.Struct {
f.Set(reflect.ValueOf(value))
}
}
}
}
我试图修复的是这个表达式f.Set(reflect.ValueOf(value))，我在这里遇到了一个错误。
英文:
I have a struct of type
type test struct {
fname string
time time.Time
}
I want to set the value of the field "time" as time.Now() using reflect package only.
I am creating a function something like this one:
func setRequestParam(arg interface{}, param string, value interface{}) {
v := reflect.ValueOf(arg).Elem()
f := v.FieldByName(param)
if f.IsValid() {
if f.CanSet() {
if f.Kind() == reflect.String {
f.SetString(value.(string))
return
} else if f.Kind() == reflect.Struct {
f.Set(reflect.ValueOf(value))
}
}
}
}
what I am trying to fix is this expression f.Set(reflect.ValueOf(value)), I am getting an error here.
答案1
得分: 2
你必须导出结构体字段，否则只有声明该结构体的包才能访问它们。
type test struct {
Fname string
Time time.Time
}
通过这个改变，你的 setRequestParam() 函数就可以工作了。
测试一下：
t := test{}
setRequestParam(&t, "Fname", "foo")
setRequestParam(&t, "Time", time.Now())
fmt.Printf("%+v\n", t)
输出结果（在 Go Playground 上尝试）：
{Fname:foo Time:2009-11-10 23:00:00 +0000 UTC m=+0.000000001}
英文:
You have to export the struct fields, else only the declaring package has access to them.
type test struct {
Fname string
Time time.Time
}
With this change your setRequestParam() function works.
Testing it:
t := test{}
setRequestParam(&t, "Fname", "foo")
setRequestParam(&t, "Time", time.Now())
fmt.Printf("%+v\n", t)
Output (try it on the Go Playground):
{Fname:foo Time:2009-11-10 23:00:00 +0000 UTC m=+0.000000001}
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