Obtain structure info

The program is:

    package main

import (
	"fmt"
	"reflect"
)

type Request struct {
	Method   string
	Resource string //path
	Protocol string
}

type s struct {
	ID        int
	Title     string
	Request   Request
	Price     float64
	Interface interface{}
	Exists    bool
	Many      []string
}

func main() {
	s := s{}    
	iterateStruct(s)
}

func iterateStruct(s interface{}) {

	e := reflect.ValueOf(s)

	for i := 0; i < e.NumField(); i++ {
		varName := e.Type().Field(i).Name
		varKind := e.Field(i).Kind()
		fmt.Println(e.Type().Field(i).Name)
		if varKind == reflect.Struct {
			//iterateStruct( <what should be here?>)
		}
		varType := e.Type().Field(i).Type
		varValue := e.Field(i).Interface()
		fmt.Printf("%v %v %v %v\n", varName, varKind, varType, varValue)
	}

}

Using recursion I'd like to get the same information for Request, that is a structure part of a structure.

What would I need to pass as a parameter? I tried various ways but I have to reckon it's a lot of trial and error for me.

Try this:

if varKind == reflect.Struct {
   iterateStruct(e.Field(i).Interface())
}

e.Field(i) returns the Value for the struct field. Interface{} will return the underlying value, so you can call iterateStruct using that.

Here's an example that handles fields with pointers to structs, interfaces containing struct value, etc.. As a bonus, this example indents nested structs.

func iterate(v reflect.Value, indent string) {
	v = reflect.Indirect(v)
	if v.Kind() != reflect.Struct {
		return
	}
	indent += "  "
	for i := 0; i < v.NumField(); i++ {
		varName := v.Type().Field(i).Name
		varKind := v.Field(i).Kind()
		varType := v.Type().Field(i).Type
		varValue := v.Field(i).Interface()
		fmt.Printf("%s%v %v %v %v\n", indent, varName, varKind, varType, varValue)
		iterate(v.Field(i), indent)
	}
}

Call it like this:

iterate(reflect.ValueOf(s), "")

https://go.dev/play/p/y1CzbKAUvD_w