How to use XML in Go?

XML is a common data exchange format. In Go language, there are many ways to manipulate XML. Here's how to use XML in Go.

1. Import the XML package

First, you need to import the encoding/xml standard library into the Go program.

import "encoding/xml"

2. Create XML structure

In Go, structures are used to represent XML data. Here is a sample XML as an example.

<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J.K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>

You can create the following Go structure to represent it:

type Bookstore struct {
    XMLName xml.Name `xml:"bookstore"`
    Books   []Book   `xml:"book"`
}

type Book struct {
    XMLName xml.Name `xml:"book"`
    Category  string    `xml:"category,attr"`
    Title  string    `xml:"title"`
    Author string    `xml:"author"`
    Year   int       `xml:"year"`
    Price  float32   `xml:"price"`
}

3. Parse the XML into the structure

Then, you can use xml.Unmarshal( )Function parses XML data into Go structure.

xml_data := []byte(`<?xml version="1.0" encoding="UTF-8"?>
<bookstore>
  <book category="children">
    <title lang="en">Harry Potter</title>
    <author>J.K. Rowling</author>
    <year>2005</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">Learning XML</title>
    <author>Erik T. Ray</author>
    <year>2003</year>
    <price>39.95</price>
  </book>
</bookstore>`)

var bookstore Bookstore
err := xml.Unmarshal(xml_data, &bookstore)
if err != nil {
    fmt.Println("error: ", err)
    return
}

fmt.Println(bookstore)

xml.Unmarshal()Parses XML data into a structure and stores the result in the bookstore variable.

4. Marshall the structure into XML

Conversely, you can use the xml.Marshal() function to marshal the structure into XML data.

bookstore := Bookstore {
    XMLName: xml.Name{Local: "bookstore"},
    Books: []Book{
        Book{
            Category: "children",
            Title:    "Harry Potter",
            Author:   "J.K. Rowling",
            Year:     2005,
            Price:    29.99,
        },
        Book{
            Category: "web",
            Title:    "Learning XML",
            Author:   "Erik T. Ray",
            Year:     2003,
            Price:    39.95,
        },
    },
}

xml_data, err := xml.MarshalIndent(bookstore, "", "  ")
if err != nil {
    fmt.Println("error: ", err)
}
fmt.Printf("%s
", xml_data)

xml.MarshalIndent()The function marshals the bookstore structure into XML data and stores the result in the variable xml_data. The first parameter is the structure to be grouped, the second parameter is the indented string to be used before each line, and the third parameter is the string to be used between each element.

5. Manipulate XML elements

In the structure, you can use XML names (such as <book>) and XML attributes (such as category) as the label of the structure field.

type Book struct {
    XMLName xml.Name `xml:"book"`
    Category string `xml:"category,attr"`
    Title    string `xml:"title"`
    Author   string `xml:"author"`
    Year     int    `xml:"year"`
    Price    int    `xml:"price"`
}

When parsing XML, the values ​​of the structure fields will be automatically populated based on the XML data.

6. Summary

Use the above steps to use XML in Go. First, you need to import the encoding/xml library, and then define a structure to represent XML data. XML data can be parsed into this structure, or this structure can be used to marshal XML data. To operate XML elements, you need to use the name and attributes of the XML element in the structure field tag.

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