Use the functions provided by the encoding/xml package to encode and decode XML, and set the indentation format and namespace

Use the functions provided by the encoding/xml package to encode and decode XML, and set the indentation format and namespace

XML (eXtensible Markup Language) as a markup for describing, transmitting and storing data language with a wide range of applications. In the Go language, you can use the functions provided by the encoding/xml package to encode and decode XML. This article will introduce how to use the encoding/xml package for XML encoding and decoding, and show how to set the indentation format and namespace.

Encoding XML data
XML encoding is the process of converting data into XML format. In the Go language, this can be achieved by creating a structure object and converting it to XML. The specific steps are as follows:

1. Define XML data structure
   First, we need to define a structure Body used to store data to be encoded as XML. The fields in the structure need to use the xml structure tag to specify the tag name and other attributes in XML.

type Person struct {
    XMLName xml.Name `xml:"person"`
    Name    string   `xml:"name"`
    Age     int      `xml:"age"`
}

In the above example, the Person structure has two fields Name and Age, which will be stored in XML respectively Display with name and age as tag names.

2. Encoding XML data
   After defining the structure, we can convert the structure object into a string in XML format. By using the MarshalIndent function, we can set the indent format. Among them, the first parameter is the io.Writer interface for writing XML data, and the second parameter is the root node of XML.

package main

import (
    "encoding/xml"
    "fmt"
    "os"
)

type Person struct {
    XMLName xml.Name `xml:"person"`
    Name    string   `xml:"name"`
    Age     int      `xml:"age"`
}

func main() {
    person := Person{
        Name: "Alice",
        Age:  30,
    }

    xmlData, err := xml.MarshalIndent(person, "", "  ")
    if err != nil {
        fmt.Println("XML encoding error:", err)
        return
    }

    os.Stdout.Write([]byte(xml.Header))
    os.Stdout.Write(xmlData)
}

Run the above code, the following XML data will be output:

<?xml version="1.0" encoding="UTF-8"?>
<person>
  <name>Alice</name>
  <age>30</age>
</person>

Decoding XML data
Decoding XML data is to convert the XML format string into the corresponding data structure. In the Go language, this can be achieved by creating a structure object and calling the Unmarshal function. The specific steps are as follows:

1. Define the XML data structure
   First, we need to define A structure used to store the result of decoding XML data. Similarly, fields in the structure need to use the xml structure tag to specify the tag name and other attributes in XML.

type Person struct {
    XMLName xml.Name `xml:"person"`
    Name    string   `xml:"name"`
    Age     int      `xml:"age"`
}

2. Decoding XML data
   After defining the structure, we can decode the XML format string into a structure object. By using the Unmarshal function, we can interpret XML data from a byte slice or a io.Reader interface.

package main

import (
    "encoding/xml"
    "fmt"
    "strings"
)

type Person struct {
    XMLName xml.Name `xml:"person"`
    Name    string   `xml:"name"`
    Age     int      `xml:"age"`
}

func main() {
    xmlData := `
        
            Alice
            30
        
    `

    person := Person{}
    err := xml.Unmarshal([]byte(xmlData), &person)
    if err != nil {
        fmt.Println("XML decoding error:", err)
        return
    }

    fmt.Println(person.Name)
    fmt.Println(person.Age)
}

Run the above code, the following results will be output:

Alice
30

Set the namespace
Namespace (Namespace) is used in XML to avoid element and attribute name conflicts mechanism. In the encoding/xml package of the Go language, we can set the namespace by using xml:"namespace-prefix:tagname" on the fields of the structure.

type Person struct {
    XMLName xml.Name `xml:"namespace-prefix:person"`
    Name    string   `xml:"name"`
    Age     int      `xml:"age"`
}

In the above example, the name of the person element will be namespace-prefix:person, where namespace-prefix is the namespace prefix.

Summary
Through the functions provided by the encoding/xml package, we can easily encode and decode XML. Through the sample code, we learned how to use the encoding/xml package to encode and decode XML, and set the indentation format and namespace. Encoding and decoding XML data will play an important role in processing API requests, configuration file parsing and other scenarios, providing convenience for Go language developers.

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