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README.md
goquery - a little like that j-thing, only in Go
goquery brings a syntax and a set of features similar to jQuery to the Go language. It is based on Go's net/html package and the CSS Selector library cascadia. Since the net/html parser returns nodes, and not a full-featured DOM tree, jQuery's stateful manipulation functions (like height(), css(), detach()) have been left off.
Also, because the net/html parser requires UTF-8 encoding, so does goquery: it is the caller's responsibility to ensure that the source document provides UTF-8 encoded HTML. See the wiki for various options to do this.
Syntax-wise, it is as close as possible to jQuery, with the same function names when possible, and that warm and fuzzy chainable interface. jQuery being the ultra-popular library that it is, I felt that writing a similar HTML-manipulating library was better to follow its API than to start anew (in the same spirit as Go's fmt
package), even though some of its methods are less than intuitive (looking at you, index()...).
Installation
Please note that because of the net/html dependency, goquery requires Go1.1+.
$ go get github.com/PuerkitoBio/goquery
(optional) To run unit tests:
$ cd $GOPATH/src/github.com/PuerkitoBio/goquery
$ go test
(optional) To run benchmarks (warning: it runs for a few minutes):
$ cd $GOPATH/src/github.com/PuerkitoBio/goquery
$ go test -bench=".*"
Changelog
Note that goquery's API is now stable, and will not break.
- 2017-02-12 (v1.1.0) : Add
SetHtml
andSetText
(thanks to @glebtv). - 2016-12-29 (v1.0.2) : Optimize allocations for
Selection.Text
(thanks to @radovskyb). - 2016-08-28 (v1.0.1) : Optimize performance for large documents.
- 2016-07-27 (v1.0.0) : Tag version 1.0.0.
- 2016-06-15 : Invalid selector strings internally compile to a
Matcher
implementation that never matches any node (instead of a panic). So for example,doc.Find("~")
returns an empty*Selection
object. - 2016-02-02 : Add
NodeName
utility function similar to the DOM'snodeName
property. It returns the tag name of the first element in a selection, and other relevant values of non-element nodes (see godoc for details). AddOuterHtml
utility function similar to the DOM'souterHTML
property (namedOuterHtml
in small caps for consistency with the existingHtml
method on theSelection
). - 2015-04-20 : Add
AttrOr
helper method to return the attribute's value or a default value if absent. Thanks to piotrkowalczuk. - 2015-02-04 : Add more manipulation functions - Prepend* - thanks again to Andrew Stone.
- 2014-11-28 : Add more manipulation functions - ReplaceWith*, Wrap* and Unwrap - thanks again to Andrew Stone.
- 2014-11-07 : Add manipulation functions (thanks to Andrew Stone) and
*Matcher
functions, that receive compiled cascadia selectors instead of selector strings, thus avoiding potential panics thrown by goquery viacascadia.MustCompile
calls. This results in better performance (selectors can be compiled once and reused) and more idiomatic error handling (you can handle cascadia's compilation errors, instead of recovering from panics, which had been bugging me for a long time). Note that the actual type expected is aMatcher
interface, thatcascadia.Selector
implements. Other matcher implementations could be used. - 2014-11-06 : Change import paths of net/html to golang.org/x/net/html (see https://groups.google.com/forum/#!topic/golang-nuts/eD8dh3T9yyA). Make sure to update your code to use the new import path too when you call goquery with
html.Node
s. - v0.3.2 : Add
NewDocumentFromReader()
(thanks jweir) which allows creating a goquery document from an io.Reader. - v0.3.1 : Add
NewDocumentFromResponse()
(thanks assassingj) which allows creating a goquery document from an http response. - v0.3.0 : Add
EachWithBreak()
which allows to break out of anEach()
loop by returning false. This function was added instead of changing the existingEach()
to avoid breaking compatibility. - v0.2.1 : Make go-getable, now that go.net/html is Go1.0-compatible (thanks to @matrixik for pointing this out).
- v0.2.0 : Add support for negative indices in Slice(). BREAKING CHANGE
Document.Root
is removed,Document
is now aSelection
itself (a selection of one, the root element, just likeDocument.Root
was before). Add jQuery's Closest() method. - v0.1.1 : Add benchmarks to use as baseline for refactorings, refactor Next...() and Prev...() methods to use the new html package's linked list features (Next/PrevSibling, FirstChild). Good performance boost (40+% in some cases).
- v0.1.0 : Initial release.
API
goquery exposes two structs, Document
and Selection
, and the Matcher
interface. Unlike jQuery, which is loaded as part of a DOM document, and thus acts on its containing document, goquery doesn't know which HTML document to act upon. So it needs to be told, and that's what the Document
type is for. It holds the root document node as the initial Selection value to manipulate.
jQuery often has many variants for the same function (no argument, a selector string argument, a jQuery object argument, a DOM element argument, ...). Instead of exposing the same features in goquery as a single method with variadic empty interface arguments, statically-typed signatures are used following this naming convention:
- When the jQuery equivalent can be called with no argument, it has the same name as jQuery for the no argument signature (e.g.:
Prev()
), and the version with a selector string argument is calledXxxFiltered()
(e.g.:PrevFiltered()
) - When the jQuery equivalent requires one argument, the same name as jQuery is used for the selector string version (e.g.:
Is()
) - The signatures accepting a jQuery object as argument are defined in goquery as
XxxSelection()
and take a*Selection
object as argument (e.g.:FilterSelection()
) - The signatures accepting a DOM element as argument in jQuery are defined in goquery as
XxxNodes()
and take a variadic argument of type*html.Node
(e.g.:FilterNodes()
) - The signatures accepting a function as argument in jQuery are defined in goquery as
XxxFunction()
and take a function as argument (e.g.:FilterFunction()
) - The goquery methods that can be called with a selector string have a corresponding version that take a
Matcher
interface and are defined asXxxMatcher()
(e.g.:IsMatcher()
)
Utility functions that are not in jQuery but are useful in Go are implemented as functions (that take a *Selection
as parameter), to avoid a potential naming clash on the *Selection
's methods (reserved for jQuery-equivalent behaviour).
The complete godoc reference documentation can be found here.
Please note that Cascadia's selectors do not necessarily match all supported selectors of jQuery (Sizzle). See the cascadia project for details. Invalid selector strings compile to a Matcher
that fails to match any node. Behaviour of the various functions that take a selector string as argument follows from that fact, e.g. (where ~
is an invalid selector string):
Find("~")
returns an empty selection because the selector string doesn't match anything.Add("~")
returns a new selection that holds the same nodes as the original selection, because it didn't add any node (selector string didn't match anything).ParentsFiltered("~")
returns an empty selection because the selector string doesn't match anything.ParentsUntil("~")
returns all parents of the selection because the selector string didn't match any element to stop before the top element.
Examples
See some tips and tricks in the wiki.
Adapted from example_test.go:
package main
import (
"fmt"
"log"
"github.com/PuerkitoBio/goquery"
)
func ExampleScrape() {
doc, err := goquery.NewDocument("http://metalsucks.net")
if err != nil {
log.Fatal(err)
}
// Find the review items
doc.Find(".sidebar-reviews article .content-block").Each(func(i int, s *goquery.Selection) {
// For each item found, get the band and title
band := s.Find("a").Text()
title := s.Find("i").Text()
fmt.Printf("Review %d: %s - %s\n", i, band, title)
})
}
func main() {
ExampleScrape()
}
License
The BSD 3-Clause license, the same as the Go language. Cascadia's license is here.