package main

import (
    "fmt"
    "os"
    "xml"
)

type Book struct {
    XMLName xml.Name    `xml:"BOOK"`
    Title string        `xml:"attr"`
    Chapters []Chapter
}

type Chapter struct {
    XMLName xml.Name    `xml:"CHAPTER"`
    Title string        `xml:"innerxml"`
    Sections []Section
}

type Section struct {
    XMLName xml.Name    `xml:"SECTION"`
    Title string
}

const filename = "test.xml"

func main() {
    oldBook := Book{XMLName: xml.Name{"", "BOOK"},
        Title: "Go",
        Chapters: []Chapter{
            Chapter{XMLName: xml.Name{"", "CHAPTER"},
                Title: "Chapter 1",
                Sections: []Section{
                    Section{XMLName: xml.Name{"", "SECTION"},
                            Title: "Section 1.1"},
                    Section{XMLName: xml.Name{"", "SECTION"},
                            Title: "Section 1.2"}}},
            Chapter{XMLName: xml.Name{"", "CHAPTER"},
                Title: "Chapter 2",
                Sections: []Section{
                    Section{XMLName: xml.Name{"", "SECTION"},
                            Title: "Section 2.1"},
                    Section{XMLName: xml.Name{"", "SECTION"},
                            Title: "Section 2.2"}}}}}

    out, err := os.Create(filename)
    if err != nil { fmt.Println(err); os.Exit(1) }
    err = xml.Marshal(out, oldBook)
    if err != nil { fmt.Println(err); os.Exit(1) }
    fmt.Fprintf(out, "\n")
    out.Close()

    in, err := os.Open(filename)
    if err != nil { fmt.Println(err); os.Exit(1) }
    var newBook Book
    err = xml.Unmarshal(in, &newBook)
    if err != nil { fmt.Println(err); os.Exit(1) }
    in.Close()
    fmt.Printf("oldBook: %#v\n", oldBook)
    fmt.Printf("newBook: %#v\n", newBook)
}