Golang : Search and extract certain XML data example
There are times when you want to just search for certain element in huge XML data set and extract the element name and associated value(chardata) or attribute value.
In this tutorial, we will learn how to extract the "normal" type of XML data. Just by the element name and get the chardata value(text in between the element name). Then, followed by extraction example of XML attribute data.
Here you go!
package main
import (
"encoding/xml"
"fmt"
"strings"
)
var XMLdata = `<urlset>
<url>
<loc>http://www.example.com/xml-element-golang</loc>
<lastmod>2015-06-14</lastmod>
<changefreq>daily</changefreq>
<priority>0.5</priority>
</url>
<url>
<loc>http://www.example.com/extract-element-by-for-loop</loc>
<lastmod>2015-06-14</lastmod>
<changefreq>daily</changefreq>
<priority>0.5</priority>
</url>
<urlset>`
var XMLdata2 = `<ALEXA VER="0.9" URL="socketloop.com/" HOME="0" AID="=" IDN="socketloop.com/">
<SD>
<POPULARITY URL="socketloop.com/" TEXT="291466" SOURCE="panel"/>
<REACH RANK="237320"/>
<RANK DELTA="+31735"/>
<COUNTRY CODE="US" NAME="United States" RANK="191742"/>
</SD>
</ALEXA>`
// ignore <loc>, only use chardata because DecodeElement will work on <loc>
type XMLQuery struct {
Loc string `xml:",chardata"`
}
var l XMLQuery
func main() {
// example on handling XML chardata(string)
decoder := xml.NewDecoder(strings.NewReader(string(XMLdata)))
for {
// err is ignore here. IF you are reading from a XML file
// do not ignore err and also check for io.EOF
token, _ := decoder.Token()
if token == nil {
break
}
switch Element := token.(type) {
case xml.StartElement:
if Element.Name.Local == "loc" {
fmt.Println("Element name is : ", Element.Name.Local)
err := decoder.DecodeElement(&l, &Element)
if err != nil {
fmt.Println(err)
}
fmt.Println("Element value is : ", l.Loc)
}
}
}
fmt.Println("------------------------------------")
// example on handling XML attribute
decoder = xml.NewDecoder(strings.NewReader(string(XMLdata2)))
for {
// err is ignore here. IF you are reading from a XML file
// do not ignore err and also check for io.EOF
token, _ := decoder.Token()
if token == nil {
break
}
switch Element := token.(type) {
case xml.StartElement:
if Element.Name.Local == "REACH" {
fmt.Println("Element name is : ", Element.Name.Local)
attrName := Element.Attr[0].Name.Local
attrValue := Element.Attr[0].Value
fmt.Printf("Attribute name is [%s] and value is [%s] \n", attrName, attrValue)
}
}
}
}
http://play.golang.org/p/b5RpnKGwsV
References :
See also : Golang : delete and modify XML file content
By Adam Ng
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