如何使用反射附加到切片？

Question

I am trying to do this:

type S struct {
    Name string
    Children []interface{}
}

func main() {
    s := S{Name: "Bob", Children: []interface{}{}}
    fmt.Println("%v", s)

    s.Children = append(s.Children, "Tom")
    fmt.Println("%v", s)

    // How do I do the above line with reflect? To add "Jane"?
    c := reflect.ValueOf(s).FieldByName("Children")
    newSlice := reflect.Append(c, reflect.ValueOf("Jane"))
    reflect.ValueOf(s).FieldByName("Children").Set(newSlice)
    fmt.Println("%v", s)
}

But I am getting the error:

panic: reflect: reflect.Value.Set using unaddressable value

What am I doing wrong?

https://play.golang.org/p/Fwy_AAF-Ls

Answer 1

Use &s to obtain addressable Value of your struct :

c := reflect.ValueOf(s).FieldByName("Children")
newSlice := reflect.Append(c, reflect.ValueOf("Jane"))
reflect.ValueOf(&s).Elem().FieldByName("Children").Set(newSlice)
fmt.Printf("%v", s)
//output:
//{Bob [Tom Jane]}

https://play.golang.org/p/y3t7mC4Lqi