travel all fields and tags of struct

travel_struct.go

func TravelStruct(v interface{}, f func(fieldName string, tag reflect.StructTag)) {
    travelStruct(reflect.ValueOf(v).Type(), f)
}

func travelStruct(t reflect.Type, f func(fieldName string, tag reflect.StructTag)) {
    t = PtrToType(t)

    if t.Kind() != reflect.Struct {
        return
    }   

    for i := 0; i < t.NumField(); i++ {
        field := t.Field(i)
        f(field.Name, field.Tag)
        fieldType := t.Field(i).Type
        fieldType = PtrToType(fieldType)
        if fieldType.Kind() == reflect.Struct {
            travelStruct(fieldType, f)
        }
    }
}

// PtrToType try to get the real value of the type point to
func PtrToType(t reflect.Type) reflect.Type {
    for t.Kind() == reflect.Ptr {
        t = t.Elem()
    }
    return t
}

usage

import (
    "fmt"
    "reflect"
)

type A struct {
    I int    `json:"test_i"`
    M string `json:"test_m"`
    *B
}

type B struct {
    N string `json:"test_n"`
    I int    `json:"test_i_in_b"`
}

func main() {
    a := &A{ 
        I: 1,
        M: "taaaa",
        B: &B{ 
            N: "OKOKOK",
            I: 123,
        },  
    }   

    TravelStruct(a, func(fieldName string, tag reflect.StructTag) {
        fmt.Println("field name: ", fieldName)
        fmt.Println("tag: ", tag.Get("json"))
    })  
    fmt.Println("Hello, playground")
}