<nil> 在golang中解析xml字符串时

Question

我想xml使用golang. 作为使用 的新手go，我阅读了网络上的文章，解释了如何解析 XML，但我不确定为什么我的返回值nil在这种情况下。

package main

import (

    "fmt"

    //"io/ioutil"

    "encoding/xml"

)

func check(e error) {

    if e != nil {

        panic(e)

    }

}

type Books struct {

    XMLName xml.Name `xml:"Books"`

    BookList []Book `xml:"Books>Book"`

}

type Book struct {

    title string `xml:"title,attr"`

    author string

    published string

}

func main() {

    //f, err := ioutil.ReadFile("xml/Books.xml")

    //check(err)

    var data = []byte(`

        <Books>

            <Book title="A Brief History of Time" author="Stephen Hawking" published="1988">

                <title>title here</title>

                A Brief History of Time: From the Big Bang to Black Holes is a 1988 popular-science book by British physicist Stephen Hawking. It became a bestseller and sold more than 10 million copies in 20 years.

            </Book>

            <Book title="Steve Jobs" author="Walter Isaacson" published="2011">

                Steve Jobs is the authorized self-titled biography book of Steve Jobs. The book was written at the request of Jobs by Walter Isaacson, a former executive at CNN.

            </Book>

        </Books>

    `)

    b := Books{}

    o := xml.Unmarshal([]byte(data), &b)

    fmt.Println(o)

}

Answer 1

我将调试反馈放在评论中，但我刚刚修改了您的示例以使其正常工作，可以在此处进行测试；https://play.golang.org/p/_UIph2je7fpackage mainimport (&nbsp; &nbsp; "fmt"&nbsp; &nbsp; //"io/ioutil"&nbsp; &nbsp; "encoding/xml")func check(e error) {&nbsp; &nbsp; if e != nil {&nbsp; &nbsp; &nbsp; &nbsp; panic(e)&nbsp; &nbsp; }}type Books struct {&nbsp; &nbsp; XMLName xml.Name `xml:"Books"`&nbsp; &nbsp; BookList []Book `xml:"Book"`}type Book struct {&nbsp; &nbsp; Title string `xml:"title,attr"`&nbsp; &nbsp; Author string `xml:"author,attr"`&nbsp; &nbsp; Published string `xml:"published,attr"`}func main() {&nbsp; &nbsp; //f, err := ioutil.ReadFile("xml/Books.xml")&nbsp; &nbsp; //check(err)&nbsp; &nbsp; var data = []byte(`&nbsp; &nbsp; &nbsp; &nbsp; <Books>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <Book title="A Brief History of Time" author="Stephen Hawking" published="1988">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <title>title here</title>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; A Brief History of Time: From the Big Bang to Black Holes is a 1988 popular-science book by British physicist Stephen Hawking. It became a bestseller and sold more than 10 million copies in 20 years.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; </Book>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; <Book title="Steve Jobs" author="Walter Isaacson" published="2011">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Steve Jobs is the authorized self-titled biography book of Steve Jobs. The book was written at the request of Jobs by Walter Isaacson, a former executive at CNN.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; </Book>&nbsp; &nbsp; &nbsp; &nbsp; </Books>&nbsp; &nbsp; `)&nbsp; &nbsp; b := Books{}&nbsp; &nbsp; o := xml.Unmarshal([]byte(data), &b)&nbsp; &nbsp; fmt.Println(o)&nbsp; &nbsp; fmt.Println(b)}这是我所做的四项更改的概要；1）打印Books对象而不是从返回的错误Unmarshal2）大写字段的第一个字母，Book使它们“导出”，以便其他包（在这种情况下为解组器）可以获取/设置它们3）添加xml属性。在导出字段时，它使它没有隐式字符串匹配，因此您必须明确指定将哪个 xml 值读入每个字段4)BookList为此更新 XML 路径，您说它将是 Books>Book 但这意味着您的 xml 中不存在另一个嵌套级别。这个对象是Books，您想要在该列表中的元素将具有简单的相对 xpath，Book这就是您放置在那里的内容。