xmlquery

Overview

xmlquery is an XPath query package for XML documents, allowing you to extract data or evaluate from XML documents with an XPath expression.

xmlquery has a built-in query object caching feature that caches recently used XPATH query strings. Enabling caching can avoid recompile XPath expression for each query.

Change Logs

2020-08-??

• Add XML stream loading and parsing support.

2019-11-11

• Add XPath query caching.

2019-10-05

• Add new methods compatible with invalid XPath expression error: QueryAll and Query.
• Add QuerySelector and QuerySelectorAll methods, support for reused query objects.
• PR #12 (Thanks @FrancescoIlario)
• PR #11 (Thanks @gjvnq)

2018-12-23

• Added XML output including comment nodes. #9

2018-12-03

• Added support to attribute name with namespace prefix and XML output. #6

Installation

 $ go get github.com/antchfx/xmlquery

Getting Started

Find specified XPath query.

list, err := xmlquery.QueryAll(doc, "a")
if err != nil {
	panic(err)
}

Parse an XML from URL.

doc, err := xmlquery.LoadURL("http://www.example.com/sitemap.xml")

Parse an XML from string.

s := `<?xml version="1.0" encoding="utf-8"?><rss version="2.0"></rss>`
doc, err := xmlquery.Parse(strings.NewReader(s))

Parse an XML from io.Reader.

f, err := os.Open("../books.xml")
doc, err := xmlquery.Parse(f)

Parse an XML in a stream fashion (simple case without elements filtering).

f, err := os.Open("../books.xml")
p, err := xmlquery.CreateStreamParser(f, "/bookstore/book")
for {
	n, err := p.Read()
	if err == io.EOF {
		break
	}
	if err != nil {
		...
	}
}

Parse an XML in a stream fashion (simple case advanced element filtering).

f, err := os.Open("../books.xml")
p, err := xmlquery.CreateStreamParser(f, "/bookstore/book", "/bookstore/book[price>=10]")
for {
	n, err := p.Read()
	if err == io.EOF {
		break
	}
	if err != nil {
		...
	}
}

Find authors of all books in the bookstore.

list := xmlquery.Find(doc, "//book//author")
// or
list := xmlquery.Find(doc, "//author")

Find the second book.

book := xmlquery.FindOne(doc, "//book[2]")

Find all book elements and only get id attribute. (New Feature)

list := xmlquery.Find(doc,"//book/@id")

Find all books with id bk104.

list := xmlquery.Find(doc, "//book[@id='bk104']")

Find all books with price less than 5.

list := xmlquery.Find(doc, "//book[price<5]")

Evaluate total price of all books.

expr, err := xpath.Compile("sum(//book/price)")
price := expr.Evaluate(xmlquery.CreateXPathNavigator(doc)).(float64)
fmt.Printf("total price: %f\n", price)

Evaluate number of all book elements.

expr, err := xpath.Compile("count(//book)")
price := expr.Evaluate(xmlquery.CreateXPathNavigator(doc)).(float64)

FAQ

Find() vs QueryAll(), which is better?

Find and QueryAll both do the same thing: searches all of matched XML nodes. Find panics if provided with an invalid XPath query, while QueryAll returns an error.

Can I save my query expression object for the next query?

Yes, you can. We provide QuerySelector and QuerySelectorAll methods; they accept your query expression object.

Caching a query expression object avoids recompiling the XPath query expression, improving query performance.

Create XML document.

doc := &xmlquery.Node{
	Type: xmlquery.DeclarationNode,
	Data: "xml",
	Attr: []xml.Attr{
		xml.Attr{Name: xml.Name{Local: "version"}, Value: "1.0"},
	},
}
root := &xmlquery.Node{
	Data: "rss",
	Type: xmlquery.ElementNode,
}
doc.FirstChild = root
channel := &xmlquery.Node{
	Data: "channel",
	Type: xmlquery.ElementNode,
}
root.FirstChild = channel
title := &xmlquery.Node{
	Data: "title",
	Type: xmlquery.ElementNode,
}
title_text := &xmlquery.Node{
	Data: "W3Schools Home Page",
	Type: xmlquery.TextNode,
}
title.FirstChild = title_text
channel.FirstChild = title
fmt.Println(doc.OutputXML(true))
// <?xml version="1.0"?><rss><channel><title>W3Schools Home Page</title></channel></rss>

Quick Tutorial

import (
	"github.com/antchfx/xmlquery"
)

func main(){
	s := `<?xml version="1.0" encoding="UTF-8" ?>
<rss version="2.0">
<channel>
  <title>W3Schools Home Page</title>
  <link>https://www.w3schools.com</link>
  <description>Free web building tutorials</description>
  <item>
    <title>RSS Tutorial</title>
    <link>https://www.w3schools.com/xml/xml_rss.asp</link>
    <description>New RSS tutorial on W3Schools</description>
  </item>
  <item>
    <title>XML Tutorial</title>
    <link>https://www.w3schools.com/xml</link>
    <description>New XML tutorial on W3Schools</description>
  </item>
</channel>
</rss>`

	doc, err := xmlquery.Parse(strings.NewReader(s))
	if err != nil {
		panic(err)
	}
	channel := xmlquery.FindOne(doc, "//channel")
	if n := channel.SelectElement("title"); n != nil {
		fmt.Printf("title: %s\n", n.InnerText())
	}
	if n := channel.SelectElement("link"); n != nil {
		fmt.Printf("link: %s\n", n.InnerText())
	}
	for i, n := range xmlquery.Find(doc, "//item/title") {
		fmt.Printf("#%d %s\n", i, n.InnerText())
	}
}

List of supported XPath query packages

Questions

Please let me know if you have any questions