:在Nokogiri中有CSS伪类 [英] :has CSS pseudo class in Nokogiri
问题描述
我在:has nofollow> Nokogiri 。
它应该像jQuery的 有
选择器。
例如:
li>< h1>< a href =dfd> ex1< / a>< / h1>< span class =string> sdfsdf< / span>< / li>
< li>< h1>< a href =dsfsdf> ex2< / a>< / h1>< span class =string>< / span> li>
< li>< h1>< a href =sdfd> ex3< / a>< / h1>< / li>
CSS选择器应该只返回第一个链接,非空的 span.string
sibling。
在jQuery中,此选择器工作良好:
$('li:has(span.string:not(:empty))> h1> a')
但不在Nokogiri中:
Nokogiri :: HTML(html_source)。 css('li:has(span.string:not(:empty))> h1> a')
:不是
和:empty
效果很好,但不是:has
。
- Nokogiri中有CSS选择器的文档吗? li>
- 也许有人可以写一个自定义
:has
伪类?这里有一个示例如何编写:regexp
selector。 - 可以选择使用XPath。如何为
li编写XPath?:has(span.string:not(:empty))> h1> a
?
Nokogiri当前实现:has()
的问题是它创建了XPath,它要求内容是一个直接子节点,而不是任何子节点:
puts Nokogiri :: CSS.xpath_for(a:has(b))
#=> // a [b]
#=>应输出//a[.b]正确
什么jQuery,你需要允许 span
是一个后代元素。例如:
require'nokogiri'
d = Nokogiri.XML('< r>< a / ;< a>< b>< / b>< / a>< / r>')
d.at_css('a:has(b)') => #< Nokogiri :: XML :: Element:0x14dd608 name =achildren = [#< Nokogiri :: XML :: Element:0x14dd3e0 name =bchildren = [#< Nokogiri :: XML :: Element :0x14dd20c name =c>]>]>
d.at_css('a:has(c)')#=> nil
d.at_xpath('// a [.// c]')#=> #< Nokogiri :: XML :: Element:0x14dd608 name =achildren = [#< Nokogiri :: XML :: Element:0x14dd3e0 name =bchildren = [#< Nokogiri :: XML :: Element :0x14dd20c name =c>]>]>
对于你的特定情况,这里是完整的破碎XPath:
puts Nokogiri :: CSS.xpath_for(li:has(span.string:not(:empty))> h1> a)
#=> // li [span [contains(concat('',@class,''),'string')and not(not(node())]] / h1 / a
这里它是固定的:
只需添加。
// li [.// span [contains(concat('',@class,''),'string')and not(not(node h1 / a
#简化为假设在span上只有一个CSS类存在
//li[./span[@class='string'而不是(不是节点))]]] / h1 / a
#假设`not(:empty)`真的意思是里面有一些文本
//li[.span[ class ='string'and text()]] / h1 / a
#..或者你真的想要在下面有一些文本
//li [@ class ='string'and .//text ()]]/h1/a
#..或者你真的想要至少有一个元素子
// li [.// span [@ class ='string'and *]] / h1 / a
I'm looking for the pseudoclass
:has
in Nokogiri. It should work just like jQuery'shas
selector.For example:
<li><h1><a href="dfd">ex1</a></h1><span class="string">sdfsdf</span></li> <li><h1><a href="dsfsdf">ex2</a></h1><span class="string"></span></li> <li><h1><a href="sdfd">ex3</a></h1></li>
The CSS selector should return only the first link, the one with the not-empty
span.string
sibling.In jQuery this selector works well:
$('li:has(span.string:not(:empty))>h1>a')
but not in Nokogiri:
Nokogiri::HTML(html_source).css('li:has(span.string:not(:empty))>h1>a')
:not
and:empty
works well, but not:has
.
- Is there any documentation for CSS selectors in Nokogiri?
- Maybe someone can write a custom
:has
pseudo class? Here is an example how to write a:regexp
selector.- Optionally I can use XPath. How do I write XPath for
li:has(span.string:not(:empty))>h1>a
?
解决方案The problem with Nokogiri's current implementation of
:has()
is that it creates XPath that requires the contents to be a direct child, not any descendant:puts Nokogiri::CSS.xpath_for( "a:has(b)" ) #=> "//a[b]" #=> Should output "//a[.//b]" to be correct
To make this XPath match what jQuery does, you need to allow the
span
to be a descendant element. For example:require 'nokogiri' d = Nokogiri.XML('<r><a/><a><b><c/></b></a></r>') d.at_css('a:has(b)') #=> #<Nokogiri::XML::Element:0x14dd608 name="a" children=[#<Nokogiri::XML::Element:0x14dd3e0 name="b" children=[#<Nokogiri::XML::Element:0x14dd20c name="c">]>]> d.at_css('a:has(c)') #=> nil d.at_xpath('//a[.//c]') #=> #<Nokogiri::XML::Element:0x14dd608 name="a" children=[#<Nokogiri::XML::Element:0x14dd3e0 name="b" children=[#<Nokogiri::XML::Element:0x14dd20c name="c">]>]>
For your specific case, here's the full "broken" XPath:
puts Nokogiri::CSS.xpath_for( "li:has(span.string:not(:empty)) > h1 > a" ) #=> //li[span[contains(concat(' ', @class, ' '), ' string ') and not(not(node()))]]/h1/a
And here it is fixed:
# Adding just the .// //li[.//span[contains(concat(' ', @class, ' '), ' string ') and not(not(node()))]]/h1/a # Simplified to assume only one CSS class is present on the span //li[.//span[@class='string' and not(not(node()))]]/h1/a # Assuming that `not(:empty)` really meant "Has some text in it" //li[.//span[@class='string' and text()]]/h1/a # ..or maybe you really wanted "Has some text anywhere underneath" //li[.//span[@class='string' and .//text()]]/h1/a # ..or maybe you really wanted "Has at least one element child" //li[.//span[@class='string' and *]]/h1/a
这篇关于:在Nokogiri中有CSS伪类的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!