Basically, the only way (that I know of) to iterate through the values of the fields of a struct
is like this:
type Example struct {
a_number uint32
a_string string
}
//...
r := &Example{(2 << 31) - 1, "...."}:
for _, d:= range []interface{}{ r.a_number, r.a_string, } {
//do something with the d
}
I was wondering, if there's a better and more versatile way of achieving []interface{}{ r.a_number, r.a_string, }
, so I don't need to list each parameter individually, or alternatively, is there a better way to loop through a struct?
I tried to look through the reflect
package, but I hit a wall, because I'm not sure what to do once I retrieve reflect.ValueOf(*r).Field(0)
.
Thanks!
After you've retrieved the reflect.Value
of the field by using Field(i)
you can get a
interface value from it by calling Interface()
. Said interface value then represents the
value of the field.
There is no function to convert the value of the field to a concrete type as there are,
as you may know, no generics in go. Thus, there is no function with the signature GetValue() T
with T
being the type of that field (which changes of course, depending on the field).
The closest you can achieve in go is GetValue() interface{}
and this is exactly what reflect.Value.Interface()
offers.
The following code illustrates how to get the values of each exported field in a struct using reflection (play):
import (
"fmt"
"reflect"
)
func main() {
x := struct{Foo string; Bar int }{"foo", 2}
v := reflect.ValueOf(x)
values := make([]interface{}, v.NumField())
for i := 0; i < v.NumField(); i++ {
values[i] = v.Field(i).Interface()
}
fmt.Println(values)
}