mirror of
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262 lines
6.4 KiB
Markdown
262 lines
6.4 KiB
Markdown
xmlquery
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====
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[](https://travis-ci.org/antchfx/xmlquery)
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[](https://coveralls.io/github/antchfx/xmlquery?branch=master)
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[](https://godoc.org/github.com/antchfx/xmlquery)
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[](https://goreportcard.com/report/github.com/antchfx/xmlquery)
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Overview
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===
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`xmlquery` is an XPath query package for XML documents, allowing you to extract
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data or evaluate from XML documents with an XPath expression.
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`xmlquery` has a built-in query object caching feature that caches recently used
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XPATH query strings. Enabling caching can avoid recompile XPath expression for
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each query.
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Change Logs
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===
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2020-08-??
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- Add XML stream loading and parsing support.
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2019-11-11
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- Add XPath query caching.
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2019-10-05
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- Add new methods compatible with invalid XPath expression error: `QueryAll` and `Query`.
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- Add `QuerySelector` and `QuerySelectorAll` methods, support for reused query objects.
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- PR [#12](https://github.com/antchfx/xmlquery/pull/12) (Thanks @FrancescoIlario)
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- PR [#11](https://github.com/antchfx/xmlquery/pull/11) (Thanks @gjvnq)
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2018-12-23
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- Added XML output including comment nodes. [#9](https://github.com/antchfx/xmlquery/issues/9)
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2018-12-03
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- Added support to attribute name with namespace prefix and XML output. [#6](https://github.com/antchfx/xmlquery/issues/6)
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Installation
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====
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```
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$ go get github.com/antchfx/xmlquery
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```
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Getting Started
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===
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### Find specified XPath query.
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```go
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list, err := xmlquery.QueryAll(doc, "a")
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if err != nil {
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panic(err)
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}
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```
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#### Parse an XML from URL.
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```go
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doc, err := xmlquery.LoadURL("http://www.example.com/sitemap.xml")
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```
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#### Parse an XML from string.
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```go
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s := `<?xml version="1.0" encoding="utf-8"?><rss version="2.0"></rss>`
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doc, err := xmlquery.Parse(strings.NewReader(s))
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```
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#### Parse an XML from io.Reader.
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```go
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f, err := os.Open("../books.xml")
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doc, err := xmlquery.Parse(f)
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```
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#### Parse an XML in a stream fashion (simple case without elements filtering).
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```go
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f, err := os.Open("../books.xml")
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p, err := xmlquery.CreateStreamParser(f, "/bookstore/book")
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for {
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n, err := p.Read()
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if err == io.EOF {
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break
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}
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if err != nil {
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...
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}
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}
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```
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#### Parse an XML in a stream fashion (simple case advanced element filtering).
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```go
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f, err := os.Open("../books.xml")
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p, err := xmlquery.CreateStreamParser(f, "/bookstore/book", "/bookstore/book[price>=10]")
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for {
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n, err := p.Read()
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if err == io.EOF {
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break
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}
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if err != nil {
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...
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}
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}
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```
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#### Find authors of all books in the bookstore.
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```go
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list := xmlquery.Find(doc, "//book//author")
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// or
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list := xmlquery.Find(doc, "//author")
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```
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#### Find the second book.
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```go
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book := xmlquery.FindOne(doc, "//book[2]")
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```
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#### Find all book elements and only get `id` attribute. (New Feature)
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```go
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list := xmlquery.Find(doc,"//book/@id")
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```
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#### Find all books with id `bk104`.
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```go
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list := xmlquery.Find(doc, "//book[@id='bk104']")
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```
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#### Find all books with price less than 5.
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```go
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list := xmlquery.Find(doc, "//book[price<5]")
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```
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#### Evaluate total price of all books.
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```go
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expr, err := xpath.Compile("sum(//book/price)")
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price := expr.Evaluate(xmlquery.CreateXPathNavigator(doc)).(float64)
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fmt.Printf("total price: %f\n", price)
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```
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#### Evaluate number of all book elements.
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```go
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expr, err := xpath.Compile("count(//book)")
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price := expr.Evaluate(xmlquery.CreateXPathNavigator(doc)).(float64)
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```
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FAQ
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====
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#### `Find()` vs `QueryAll()`, which is better?
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`Find` and `QueryAll` both do the same thing: searches all of matched XML nodes.
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`Find` panics if provided with an invalid XPath query, while `QueryAll` returns
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an error.
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#### Can I save my query expression object for the next query?
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Yes, you can. We provide `QuerySelector` and `QuerySelectorAll` methods; they
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accept your query expression object.
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Caching a query expression object avoids recompiling the XPath query
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expression, improving query performance.
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#### Create XML document.
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```go
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doc := &xmlquery.Node{
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Type: xmlquery.DeclarationNode,
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Data: "xml",
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Attr: []xml.Attr{
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xml.Attr{Name: xml.Name{Local: "version"}, Value: "1.0"},
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},
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}
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root := &xmlquery.Node{
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Data: "rss",
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Type: xmlquery.ElementNode,
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}
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doc.FirstChild = root
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channel := &xmlquery.Node{
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Data: "channel",
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Type: xmlquery.ElementNode,
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}
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root.FirstChild = channel
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title := &xmlquery.Node{
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Data: "title",
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Type: xmlquery.ElementNode,
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}
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title_text := &xmlquery.Node{
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Data: "W3Schools Home Page",
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Type: xmlquery.TextNode,
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}
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title.FirstChild = title_text
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channel.FirstChild = title
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fmt.Println(doc.OutputXML(true))
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// <?xml version="1.0"?><rss><channel><title>W3Schools Home Page</title></channel></rss>
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```
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Quick Tutorial
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===
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```go
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import (
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"github.com/antchfx/xmlquery"
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)
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func main(){
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s := `<?xml version="1.0" encoding="UTF-8" ?>
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<rss version="2.0">
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<channel>
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<title>W3Schools Home Page</title>
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<link>https://www.w3schools.com</link>
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<description>Free web building tutorials</description>
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<item>
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<title>RSS Tutorial</title>
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<link>https://www.w3schools.com/xml/xml_rss.asp</link>
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<description>New RSS tutorial on W3Schools</description>
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</item>
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<item>
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<title>XML Tutorial</title>
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<link>https://www.w3schools.com/xml</link>
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<description>New XML tutorial on W3Schools</description>
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</item>
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</channel>
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</rss>`
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doc, err := xmlquery.Parse(strings.NewReader(s))
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if err != nil {
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panic(err)
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}
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channel := xmlquery.FindOne(doc, "//channel")
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if n := channel.SelectElement("title"); n != nil {
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fmt.Printf("title: %s\n", n.InnerText())
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}
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if n := channel.SelectElement("link"); n != nil {
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fmt.Printf("link: %s\n", n.InnerText())
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}
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for i, n := range xmlquery.Find(doc, "//item/title") {
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fmt.Printf("#%d %s\n", i, n.InnerText())
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}
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}
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```
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List of supported XPath query packages
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===
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| Name | Description |
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| ------------------------------------------------- | ----------------------------------------- |
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| [htmlquery](https://github.com/antchfx/htmlquery) | XPath query package for HTML documents |
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| [xmlquery](https://github.com/antchfx/xmlquery) | XPath query package for XML documents |
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| [jsonquery](https://github.com/antchfx/jsonquery) | XPath query package for JSON documents |
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Questions
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===
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Please let me know if you have any questions
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