使用反射在Golang中打印结构指针字段类型

Question

I have a struct and I am trying to iterate through all fields to determine whether or not the field is a map (or a pointer to a map). I'm able to compare field kind to reflect.Map for non-pointer fields, but I am having trouble doing the same for pointer fields. If the field has a value I can use Elem() to determine the pointer field type, but if the field is nil that method won't work and I get "invalid." Any ideas on how to accomplish this? Playground is here.

package main

import (
    "fmt"
    "reflect"
)

type Item struct {
    itemMap    map[string]interface{}
    itemMapPtr *map[string]interface{}
}

func main() {
    item := new(Item)
    printTypes(*item)
}

func printTypes(item Item) {
    itemVal := reflect.ValueOf(item)
    for i := 0; i < itemVal.NumField(); i++ {
        fieldVal := itemVal.Field(i)
        if fieldVal.Kind() == reflect.Ptr {
            fieldVal = fieldVal.Elem() // This is only helpful if the field is not nil
        }
        fmt.Println(fieldVal.Kind())
    }
}

Answer 1

Work with types instead of values:

t := reflect.TypeOf(item)
for i := 0; i < t.NumField(); i++ {
    ft := t.Field(i).Type
    if ft.Kind() == reflect.Ptr {
        ft = ft.Elem()
    }
    fmt.Println(ft.Kind())
}

playground example