***see updated field at the bottom,please****
I want to assign a value to a nested struct but it does not work:
try code here
type MyStruct2 struct {
Value3 string
}
type myStruct1 struct {
Value1 string
Value2 int
MyStruct2 MyStruct2
}
func main() {
var ah myStruct1
t := reflect.TypeOf(ah)
where := reflect.ValueOf(&ah).Elem()
rt0 := t.Field(0)
field0 := where.FieldByIndex(rt0.Index)
field0.SetString("hello")
rt1 := t.Field(1)
field1 := where.FieldByIndex(rt1.Index)
field1.SetInt(4)
rt2 := t.Field(2)
rt2_1:=rt2.Type.Field(0)
field2 := where.FieldByIndex(rt2_1.Index)
field2.SetString("hello2")//not assigning to struct
fmt.Printf("%+v\n",ah)
}
output: {Value1:hello2 Value2:4 MyStruct2:{Value3:}}
As you can see, it's not assigning a value to the nested struct
// update:
as @Austin said this is solved by using:
field2 :=where.FieldByIndex(rt2.Index).FieldByIndex(rt2_1.Index)
instead, but it's not working inside function:
try code here
type MyStruct2 struct {
Value3 string
}
type myStruct1 struct {
Value1 string
Value2 string
MyStruct2 MyStruct2
}
func main() {
var ah myStruct1
t := reflect.TypeOf(ah)
where := reflect.ValueOf(&ah).Elem()
max := t.NumField()
for i := 0; i < max; i++ {
f := t.Field(i)
findAssing("hello", f, where)
}
fmt.Printf("%+v\n", ah)
}
func findAssing(me string, rt reflect.StructField, field reflect.Value) {
if rt.Type.Kind() == reflect.Struct {
max := rt.Type.NumField()
for i := 0; i < max; i++ {
if rt.Type.Field(i).Type.Kind() == reflect.Struct {
field = field.FieldByIndex(rt.Type.Field(i).Index)
}
findAssing(me, rt.Type.Field(i), field)
}
} else {
field = field.FieldByIndex(rt.Index)
field.SetString("hello")
}
}
You need to select the third field of the outer struct before you select the first field of the inner struct. Ie,
rt2 := t.Field(2)
rt2_1 := rt2.Type.Field(0)
field2 := where.FieldByIndex(rt2.Index).FieldByIndex(rt2_1.Index)
field2.SetString("hello2") // Will assign to the inner struct now.
Edit: The code in the edited question makes a similar mistake in that it does not fetch the field of the outer struct first. Additionally, it overrides the value of field repeatedly in a way that probably doesn't do what is intended. Something like this should work:
func findAssing(me string, rt reflect.StructField, field reflect.Value) {
subField := field.FieldByIndex(rt.Index)
if rt.Type.Kind() == reflect.Struct {
max := rt.Type.NumField()
for i := 0; i < max; i++ {
findAssing(me, rt.Type.Field(i), subField)
}
} else {
subField.SetString("hello")
}
}
If your goal is recursively set all string fields to some value, then use the following code. You don't say what the code is supposed to do, so this is just a guess.
func main() {
var ah myStruct1
setStringsInStruct("hello", reflect.ValueOf(&ah).Elem())
fmt.Printf("%+v\n", ah)
}
func setStringsInStruct(s string, v reflect.Value) {
t := v.Type()
for i := 0; i < t.NumField(); i++ {
sf := t.Field(i)
switch sf.Type.Kind() {
case reflect.Struct:
setStringsInStruct(s, v.Field(i))
case reflect.String:
v.Field(i).SetString(s)
}
}
}
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