How to access a unexported nested struct field from struct using reflect?

Asked Apr 23 '22 at 18:33

Active Apr 23 '22 at 18:33

Viewed 29 times

I am trying to access a nested struct (time.Time) within a struct using the reflect package. However, when trying to access it as an interface, I get the following error:

reflect.Value.Interface: cannot return value obtained from unexported field or method

How can I access this struct natively?

Example:

package main

import (
    "fmt"
    "reflect"
    "time"
)

type Foo struct {
    t time.Time
}

func main() {
    foo := Foo{t: time.Now()}
    v := reflect.ValueOf(foo)
    f := v.FieldByName("t")

    fmt.Printf("%T %v\n", f, f) // reflect.Value {13454110244426743808 1 0x5378e0}
    t := f.Interface().(time.Time)

    fmt.Printf("%T %v\n", t, t)
}

Go Playground: https://go.dev/play/p/O_jLStsd339

asked Apr 23 '22 at 18:33

tomwassing

You can’t. Unexported means unaccessible. – Volker Apr 23 '22 at 18:37
@Volker No? https://stackoverflow.com/questions/42664837/how-to-access-unexported-struct-fields/43918797#43918797 – tomwassing Apr 23 '22 at 18:38
2

@tomwassing using unsafe almost everything is possible, but it can't be done with reflection alone. How does this question differ from the one you are citing? – Dylan Reimerink Apr 23 '22 at 20:01
@tomwassing. No. unsafe is _the_ way to that kind of problems nobody want's. Just switch to C if you think that's clever. – Volker Apr 24 '22 at 07:29
@DylanReimerink Thanks Dylan, I'm going to look into that! – tomwassing Apr 26 '22 at 08:35

How to access a unexported nested struct field from struct using reflect?

0 Answers0