I'm trying to update all string fields in a struct and its subfields using reflection in golang for an arbitrary struct as follows:
package main
import (
"fmt"
"reflect"
"strings"
)
func main() {
type Inner struct {
In1 string
In2 []string
}
type Type struct {
Name string
Names []string
NewSt Inner
}
a := Type{
Name: " [ (Amir[ ",
Names: nil,
NewSt: Inner{
In1: " [in1",
In2: []string{" [in2( "},
},
}
trims(&a)
fmt.Printf("%#v\n", a)
}
func trim(str string) string {
return strings.TrimSpace(strings.Trim(str, "[](){}, "))
}
func trims(ps interface{}) {
v := reflect.ValueOf(ps).Elem() // Elem() dereferences pointer
for i := 0; i < v.NumField(); i {
fv := v.Field(i)
switch fv.Kind() {
case reflect.String:
fv.SetString(trim(fv.String()))
case reflect.Struct:
in := fv.Interface()
trims(&in)
}
}
}
But I get panic: reflect: call of reflect.Value.Elem on struct Value error. How can I fix it or is there any better way that I can do such thing??
Thanks.
CodePudding user response：
func trims(ps interface{}) {
v := reflect.ValueOf(ps)
if v.Kind() == reflect.Ptr {
v = v.Elem() // Elem() dereferences pointer
}
if v.Kind() != reflect.Struct {
panic("not struct")
}
for i := 0; i < v.NumField(); i {
fv := v.Field(i)
switch fv.Kind() {
case reflect.String:
fv.SetString(trim(fv.String()))
case reflect.Struct:
// use Addr() to get an addressable
// value of the field
in := fv.Addr().Interface()
// do not use &in, that evaluates
// to *interface{}, that's almost
// NEVER what you want
trims(in)
case reflect.Slice:
if fv.Type().Elem().Kind() == reflect.String {
for i := 0; i < fv.Len(); i {
fv.Index(i).SetString(trim(fv.Index(i).String()))
}
}
}
}
}