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Martin Angers
2014-11-07 09:57:08 -05:00
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[![GoDoc](https://godoc.org/github.com/PuerkitoBio/goquery?status.png)](http://godoc.org/github.com/PuerkitoBio/goquery)
GoQuery brings a syntax and a set of features similar to [jQuery][] to the [Go language][go]. It is based on Go's [net/html package][html] and the CSS Selector library [cascadia][]. Since the net/html parser returns tokens (nodes), and not a full-featured DOM object with a rendering engine, jQuery's stateful manipulation functions (like height(), css(), detach()) have been left off as they can't really be used.
goquery brings a syntax and a set of features similar to [jQuery][] to the [Go language][go]. It is based on Go's [net/html package][html] and the CSS Selector library [cascadia][]. Since the net/html parser returns tokens (nodes), and not a full-featured DOM tree, jQuery's stateful manipulation functions (like height(), css(), detach()) have been left off as they can't really be used.
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.
Supported functions are query-oriented features (`hasClass()`, `attr()` and the likes), as well as traversing functions that make sense given what we have to work with. This makes GoQuery a great library for scraping web pages.
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()][index]...).
@@ -32,6 +30,7 @@ Please note that because of the net/html dependency, goquery requires Go1.1+.
**Note that goquery's API is now stable, and will not break.**
* **2014-11-08** : Add manipulation functions (thanks to [Andrew Stone][thatguystone]) and `*Matcher` functions, that receive compiled cascadia selectors instead of selector strings, thus avoiding potential panics thrown by goquery via `cascadia.MustCompile` calls. This results in better performance (selectors can be compiled once and reused) and better error handling (you can handle cascadia's compilation errors). Note that the actual type expected is a `Matcher` interface, that `cascadia.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.
@@ -43,19 +42,20 @@ Please note that because of the net/html dependency, goquery requires Go1.1+.
## API
GoQuery exposes two classes, `Document` and `Selection`. 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` class is for. It holds the root document node as the initial Selection object to manipulate.
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, I use statically-typed signatures following this naming convention:
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 called `XxxFiltered()` (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()`)
* Finally, 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 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 as `XxxMatcher()` (e.g.: `IsMatcher()`)
GoQuery's complete [godoc reference documentation can be found here][doc].
The complete [godoc reference documentation can be found here][doc].
Please note that Cascadia's selectors do NOT necessarily match all supported selectors of jQuery (Sizzle). See the [cascadia project][cascadia] for details.
Please note that Cascadia's selectors do not necessarily match all supported selectors of jQuery (Sizzle). See the [cascadia project][cascadia] for details.
## Examples
@@ -106,3 +106,4 @@ The [BSD 3-Clause license][bsd], the same as the [Go language][golic]. Cascadia'
[gonet]: http://code.google.com/p/go/source/detail?r=f7f5159120f51ba0070774d3c5907969b5fe7858&repo=net
[html]: http://godoc.org/code.google.com/p/go.net/html
[wiki]: https://github.com/PuerkitoBio/goquery/wiki/Tips-and-tricks
[thatguystone]: https://github.com/thatguystone