blocks|key|266779|text|html+=+<<HTML
++<div+id="block">
++++<a+href="http://google.com">link</a>
++</div>
HTML
doc+=+Nokogiri::HTML(html)
doc.xpath('//div/a/@href')
#=>+[#<Nokogiri::XML::Attr:0x80887798+name="href"+value="http://google.com">]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|266780|或者，如果您想更具体地了解div：|unstyled|266781|>>+doc.xpath('//div[@id="block"]/a/@href')
=>+[#<Nokogiri::XML::Attr:0x80887798+name="href"+value="http://google.com">]
>>+doc.xpath('//div[@id="block"]/a/@href').first.value
=>+"http://google.com"|266782|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>html = &lt;&lt;HTML
  &lt;div id="block"&gt;
    &lt;a href="http://google.com"&gt;link&lt;/a&gt;
  &lt;/div&gt;
HTML
doc = Nokogiri::HTML(html)
doc.xpath('//div/a/@href')
#=&gt; [#&lt;Nokogiri::XML::Attr:0x80887798 name="href" value="http://google.com"&gt;]
</code></pre>

<p>Or if you wanna be more specific about the div:</p>

<pre><code>&gt;&gt; doc.xpath('//div[@id="block"]/a/@href')
=&gt; [#&lt;Nokogiri::XML::Attr:0x80887798 name="href" value="http://google.com"&gt;]
&gt;&gt; doc.xpath('//div[@id="block"]/a/@href').first.value
=&gt; "http://google.com"
</code></pre>


blocks|key|266784|text|doc+=+Nokogiri::HTML("HTML+...")
href+=+doc.css("div[id='block']+>+a")
result+=+href['href']+#http://google.com|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|266785|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>doc = Nokogiri::HTML("HTML ...")
href = doc.css("div[id='block'] &gt; a")
result = href['href'] #http://google.com
</code></pre>


blocks|key|3684143|text|doc+=+Nokogiri::HTML(open("[insert+URL+here]"))
href+=+doc.css('#block+a')[0]["href"]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3684144|变量href被赋值给id为'block'的元素内<a>元素的"href"属性值。行doc.css('#block+a')返回一个包含#block+a属性的单项数组。[0]以单个元素为目标，该元素是一个包含所有属性名称和值的散列。["href"]针对该散列中的"href"的键并返回值，该值是一个包含url的字符串。|unstyled|offset|length|style|CODE|3684145|entityMap^0|0|2|4|D|7|O|3|U|6|15|J|1U|8|2A|3|36|8|3L|6|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]|$G|Q|H|R|I|J]|$G|S|H|T|I|J]|$G|U|H|V|I|J]|$G|W|H|X|I|J]|$G|Y|H|Z|I|J]|$G|10|H|11|I|J]|$G|12|H|13|I|J]|$G|14|H|15|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|16|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>doc = Nokogiri::HTML(open("[insert URL here]"))
href = doc.css('#block a')[0]["href"]
</code></pre>

<p>The variable <code>href</code> is assigned to the value of the <code>"href"</code> attribute for the <code>&lt;a&gt;</code> element inside the element with id <code>'block'</code>.  The line <code>doc.css('#block a')</code> returns a single item array containing the attributes of <code>#block a</code>.  <code>[0]</code> targets that single element, which is a hash containing all the attribute names and values.  <code>["href"]</code> targets the key of <code>"href"</code> inside that hash and returns the value, which is a string containing the url.     </p>


blocks|key|3684188|text|在以各种形式努力解决这个问题后，我决定给自己写一个伪装成答案的教程。这可能会对其他人有所帮助。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3684189|从下面的代码片段开始：|3684190|require+'rubygems'
require+'nokogiri'

html+=+<<HTML
<div+id="block1">
++++<a+href="http://google.com">link1</a>
</div>
<div+id="block2">
++++<a+href="http://stackoverflow.com">link2</a>
++++<a+id="tips">just+a+bookmark</a>
</div>
HTML

doc+=+Nokogiri::HTML(html)|code-block|syntax|javascript|3684191|提取所有链接|3684192|我们可以使用xpath或css来查找所有元素，然后只保留那些具有href属性的元素：|offset|length|style|CODE|3684193|nodeset+=+doc.xpath('//a')++++++#+Get+all+anchors+via+xpath
nodeset.map+{%7Celement%7C+element["href"]}.compact++#+=>+["http://google.com",+"http://stackoverflow.com"]

nodeset+=+doc.css('a')++++++++++#+Get+all+anchors+via+css
nodeset.map+{%7Celement%7C+element["href"]}.compact++#+=>+["http://google.com",+"http://stackoverflow.com"]|3684194|但还有一种更好的方法:在上述情况下，.compact是必需的，因为搜索也会返回“只是一个书签”元素。我们可以使用更精细的搜索来仅查找包含href属性的元素：|3684195|attrs+=+doc.xpath('//a/@href')++#+Get+anchors+w+href+attribute+via+xpath
attrs.map+{%7Cattr%7C+attr.value}+++#+=>+["http://google.com",+"http://stackoverflow.com"]

nodeset+=+doc.css('a[href]')++++#+Get+anchors+w+href+attribute+via+css
nodeset.map+{%7Celement%7C+element["href"]}++#+=>+["http://google.com",+"http://stackoverflow.com"]|3684196|查找特定链接|3684197|在<div+id="block2">中查找链接的步骤|3684198|nodeset+=+doc.xpath('//div[@id="block2"]/a/@href')
nodeset.first.value+#+=>+"http://stackoverflow.com"

nodeset+=+doc.css('div#block2+a[href]')
nodeset.first['href']+#+=>+"http://stackoverflow.com"|3684199|如果你知道你只搜索一个链接，你可以改用at_xpath或at_css：|3684200|attr+=+doc.at_xpath('//div[@id="block2"]/a/@href')
attr.value++++++++++#+=>+"http://stackoverflow.com"

element+=+doc.at_css('div#block2+a[href]')
element['href']++++++++#+=>+"http://stackoverflow.com"|3684201|从关联文本中查找链接|3684202|如果你知道与链接相关的文本并想要找到它的url，该怎么办？一点xpath-fu+(或css-fu)就派上用场了：|3684203|element+=+doc.at_xpath('//a[text()="link2"]')
element["href"]+++++#+=>+"http://stackoverflow.com"

element+=+doc.at_css('a:contains("link2")')
element["href"]+++++#+=>+"http://stackoverflow.com"|3684204|从链接查找文本|3684205|如果您想要查找与特定链接相关联的文本，该怎么办？不成问题：|3684206|element+=+doc.at_xpath('//a[@href="http://stackoverflow.com"]')
element.text+++++#+=>+"link2"

element+=+doc.at_css('a[href="http://stackoverflow.com"]')
element.text+++++#+=>+"link2"|3684207|有用的参考资料|3684208|除了广泛的Nokorigi+documentation之外，我在写这篇文章的时候还发现了一些有用的链接：|3684209|3684210|a+handy+Nokogiri+cheat+sheet|unordered-list-item|3684211|a+tutorial+on+parsing+HTML+with+Nokogiri|3684212|interactively+test+CSS+selector+queries|3684213|3684214|entityMap|0|LINK|mutability|MUTABLE|url|http://nokogiri.org/|1|https://github.com/sparklemotion/nokogiri/wiki/Cheat-sheet|2|http://ruby.bastardsbook.com/chapters/html-parsing/|3|http://try.jsoup.org/^0|0|0|0|0|W|4|0|0|I|8|1W|4|0|0|0|1|H|0|0|J|8|S|6|0|0|0|0|0|0|0|0|0|5|M|0|0|0|0|S|1|0|0|14|2|0|0|13|3|0|0^^$0|@$1|2|3|4|5|6|7|29|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|2A|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|2B|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|2C|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|2D|8|@$M|2E|N|2F|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|F|7|2G|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|2H|8|@$M|2I|N|2J|O|P]|$M|2K|N|2L|O|P]]|9|@]|A|$]]|$1|U|3|V|5|F|7|2M|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|2N|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|2O|8|@$M|2P|N|2Q|O|P]]|9|@]|A|$]]|$1|10|3|11|5|F|7|2R|8|@]|9|@]|A|$G|H]]|$1|12|3|13|5|6|7|2S|8|@$M|2T|N|2U|O|P]|$M|2V|N|2W|O|P]]|9|@]|A|$]]|$1|14|3|15|5|F|7|2X|8|@]|9|@]|A|$G|H]]|$1|16|3|17|5|6|7|2Y|8|@]|9|@]|A|$]]|$1|18|3|19|5|6|7|2Z|8|@]|9|@]|A|$]]|$1|1A|3|1B|5|F|7|30|8|@]|9|@]|A|$G|H]]|$1|1C|3|1D|5|6|7|31|8|@]|9|@]|A|$]]|$1|1E|3|1F|5|6|7|32|8|@]|9|@]|A|$]]|$1|1G|3|1H|5|F|7|33|8|@]|9|@]|A|$G|H]]|$1|1I|3|1J|5|6|7|34|8|@]|9|@]|A|$]]|$1|1K|3|1L|5|6|7|35|8|@]|9|@$M|36|N|37|1|38]]|A|$]]|$1|1M|3|-4|5|6|7|39|8|@]|9|@]|A|$]]|$1|1N|3|1O|5|1P|7|3A|8|@]|9|@$M|3B|N|3C|1|3D]]|A|$]]|$1|1Q|3|1R|5|1P|7|3E|8|@]|9|@$M|3F|N|3G|1|3H]]|A|$]]|$1|1S|3|1T|5|1P|7|3I|8|@]|9|@$M|3J|N|3K|1|3L]]|A|$]]|$1|1U|3|-4|5|6|7|3M|8|@]|9|@]|A|$]]|$1|1V|3|-4|5|6|7|3N|8|@]|9|@]|A|$]]]|1W|$1X|$5|1Y|1Z|20|A|$21|22]]|23|$5|1Y|1Z|20|A|$21|24]]|25|$5|1Y|1Z|20|A|$21|26]]|27|$5|1Y|1Z|20|A|$21|28]]]]

<p>Having struggled with this question in various forms, I decided to write myself a tutorial disguised as an answer.  It may be helpful to others.</p>

<p>Starting with with this snippet:</p>

<pre><code>require 'rubygems'
require 'nokogiri'

html = &lt;&lt;HTML
&lt;div id="block1"&gt;
    &lt;a href="http://google.com"&gt;link1&lt;/a&gt;
&lt;/div&gt;
&lt;div id="block2"&gt;
    &lt;a href="http://stackoverflow.com"&gt;link2&lt;/a&gt;
    &lt;a id="tips"&gt;just a bookmark&lt;/a&gt;
&lt;/div&gt;
HTML

doc = Nokogiri::HTML(html)
</code></pre>

<h2>extracting all the links</h2>

<p>We can use xpath or css to find all the  elements and then keep only the ones that have an <code>href</code> attribute:</p>

<pre><code>nodeset = doc.xpath('//a')      # Get all anchors via xpath
nodeset.map {|element| element["href"]}.compact  # =&gt; ["http://google.com", "http://stackoverflow.com"]

nodeset = doc.css('a')          # Get all anchors via css
nodeset.map {|element| element["href"]}.compact  # =&gt; ["http://google.com", "http://stackoverflow.com"]
</code></pre>

<p>But there's a better way: in the above cases, the <code>.compact</code> is necessary because the searches return the "just a bookmark" element as well.  We can use a more refined search to find just the elements that contain an <code>href</code> attribute:</p>

<pre><code>attrs = doc.xpath('//a/@href')  # Get anchors w href attribute via xpath
attrs.map {|attr| attr.value}   # =&gt; ["http://google.com", "http://stackoverflow.com"]

nodeset = doc.css('a[href]')    # Get anchors w href attribute via css
nodeset.map {|element| element["href"]}  # =&gt; ["http://google.com", "http://stackoverflow.com"]
</code></pre>

<h2>finding a specific link</h2>

<p>To find a link within the <code>&lt;div id="block2"&gt;</code></p>

<pre><code>nodeset = doc.xpath('//div[@id="block2"]/a/@href')
nodeset.first.value # =&gt; "http://stackoverflow.com"

nodeset = doc.css('div#block2 a[href]')
nodeset.first['href'] # =&gt; "http://stackoverflow.com"
</code></pre>

<p>If you know you're searching for just one link, you can use <code>at_xpath</code> or <code>at_css</code> instead:</p>

<pre><code>attr = doc.at_xpath('//div[@id="block2"]/a/@href')
attr.value          # =&gt; "http://stackoverflow.com"

element = doc.at_css('div#block2 a[href]')
element['href']        # =&gt; "http://stackoverflow.com"
</code></pre>

<h2>find a link from associated text</h2>

<p>What if you know the text associated with a link and want to find its url?  A little xpath-fu (or css-fu) comes in handy:</p>

<pre><code>element = doc.at_xpath('//a[text()="link2"]')
element["href"]     # =&gt; "http://stackoverflow.com"

element = doc.at_css('a:contains("link2")')
element["href"]     # =&gt; "http://stackoverflow.com"
</code></pre>

<h2>find text from a link</h2>

<p>And what if you want to find the text associated with a particular link?
  Not a problem:</p>

<pre><code>element = doc.at_xpath('//a[@href="http://stackoverflow.com"]')
element.text     # =&gt; "link2"

element = doc.at_css('a[href="http://stackoverflow.com"]')
element.text     # =&gt; "link2"
</code></pre>

<h2>useful references</h2>

<p>In addition to the extensive <a href="http://nokogiri.org/" rel="noreferrer">Nokorigi documentation</a>, I came across some useful links while writing this up:</p>

<ul>
<li><a href="https://github.com/sparklemotion/nokogiri/wiki/Cheat-sheet" rel="noreferrer">a handy Nokogiri cheat sheet</a></li>
<li><a href="http://ruby.bastardsbook.com/chapters/html-parsing/" rel="noreferrer">a tutorial on parsing HTML with Nokogiri</a></li>
<li><a href="http://try.jsoup.org/" rel="noreferrer">interactively test CSS selector queries</a></li>
</ul>


blocks|key|3684236|text|data+=+'<html+lang="en"+class="">
++++<head>
++++<a+href="https://example.com/9f40a.css"+media="all"+rel="stylesheet"+/>+link1</a>
++++<a+href="https://example.com/4e5fb.css"+media="all"+rel="stylesheet"+/>link2</a>
++++<a+href="https://example.com/5s5fb.css"+media="all"+rel="stylesheet"+/>link3</a>
+++</head>
++</html>'|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3684237|下面是我对上面HTML代码示例的尝试：|unstyled|3684238|doc+=+Nokogiri::HTML(data)
doc.xpath('//@href').map(&:value)
=>+[https://example.com/9f40a.css,+https://example.com/4e5fb.css,+https://example.com/5s5fb.css]|3684239|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>data = '&lt;html lang="en" class=""&gt;
    &lt;head&gt;
    &lt;a href="https://example.com/9f40a.css" media="all" rel="stylesheet" /&gt; link1&lt;/a&gt;
    &lt;a href="https://example.com/4e5fb.css" media="all" rel="stylesheet" /&gt;link2&lt;/a&gt;
    &lt;a href="https://example.com/5s5fb.css" media="all" rel="stylesheet" /&gt;link3&lt;/a&gt;
   &lt;/head&gt;
  &lt;/html&gt;'
</code></pre>

<p>Here is my Try for above sample of HTML code:</p>

<pre><code>doc = Nokogiri::HTML(data)
doc.xpath('//@href').map(&amp;:value)
=&gt; [https://example.com/9f40a.css, https://example.com/4e5fb.css, https://example.com/5s5fb.css]
</code></pre>


blocks|key|267547|text|document.css("#block+a")["href"]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|267548|其中document是经过分析的Nokogiri+HTML。|unstyled|offset|length|style|CODE|267549|entityMap^0|0|2|8|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>document.css("#block a")["href"]
</code></pre>

<p>where <code>document</code> is the Nokogiri HTML parsed.</p>


<p>I have a document which look like this:</p>

<pre><code>&lt;div id="block"&gt;
    &lt;a href="http://google.com"&gt;link&lt;/a&gt;
&lt;/div&gt;
</code></pre>

<p>I can't get Nokogiri to get me the value of <code>href</code> attribute. I'd like to store the address in a Ruby variable as a string.</p>


Getting attribute's value in Nokogiri to extract link URLs

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个文档，看起来像这样：<div id="block">    <a href="http://google.com">link</a></div>我无法让Nokogiri获取href属性的值。我想将地址作为字符串存储在Ruby变量中。

问获取Nokogiri中的属性值以提取链接URL
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问获取Nokogiri中的属性值以提取链接URLEN