反射：调用ptr Value上的reflect.Value.Field

Question

Im trying to map map[string]interface{} to structure. My structure contains pointer types:

type A struct{
  f1 string
  f2 *B
}

type B {
  f1 string
  f2 string
}

when I am trying to iterate through *B, I've got:

"reflect: call of reflect.Value.Field on ptr Value"

val from output is following:

<*B Value>

Code:

func processNode(v *reflect.Value, t reflect.Type, data interface{}) error {
        for i := 0; i < t.NumField(); i++ {
            var f reflect.Value

            if isPointer(v.Type()) {
                fmt.Printf("val: %s
", v)
                f = v.Field(i)              //Fails here!
            } else {
                f = v.Field(i)
            }

            ft := t.Field(i)
            m := data.(map[string]interface{})

            val, ok := findFieldValue(m, ft.Name)
            if ok {
                if isPointer(ft.Type) && !isSimpleType(ft.Type) {
                    processNode(&f, ft.Type.Elem(), val)
                } else if !isSimpleType(ft.Type) {
                    processNode(&f, ft.Type, val)
                } else {

                    err := setTyped(&f, val)
                    if err != nil {
                        return err
                    }
                }
            }
    }

    return nil
}

I wondering, how to iterate through reference value? (iteration works fine on A)

Answer 1

The code dereferences the field's type, but not the field's value. Change

if isPointer(ft.Type) && !isSimpleType(ft.Type) {
    processNode(&f, ft.Type.Elem(), val)
    ...

to:

if isPointer(ft.Type) && !isSimpleType(ft.Type) {
    fv := f.Elem()
    processNode(&fv, ft.Type.Elem(), val)
    ...