用Nokogiri :: HTML进行爬网-无法从XPATH获取文本

Question

I'm trying to scrape html with Nokogiri. This is the html source:

<span id="J_WlAreaInfo" class="wl-areacon">
    <span id="J-From">山东济南</span>
    至
    <span id="J-To">
        <span id="J_WlAddressInfo" class="wl-addressinfo" title="全国">
            全国
            <s></s>
        </span>
    </span>
</span> 

I need to get the following text: 山东济南

Checked shortest XPATH with firebug:

//*[@id="J-From"]

Here is my ruby code:

doc = Nokogiri::HTML(open("http://foo.html"), "UTF-8")
area = doc.xpath('//*[@id="J-From"]')
puts area.text

However, it returns nothing. What am I doing wrong?

Answer 1

However, it returns nothing. What am I doing wrong?

xpath() returns an array containing the matches (it's actually called a NodeSet):

require 'nokogiri'


html = %q{
<span id="J_WlAreaInfo" class="wl-areacon">
    <span id="J-From">山东济南</span>
    至
    <span id="J-To">
        <span id="J_WlAddressInfo" class="wl-addressinfo" title="全国">
            全国
            <s></s>
        </span>
    </span>
</span> 
}

doc = Nokogiri::HTML(html)
target_tags = doc.xpath('//*[@id="J-From"]')

target_tags.each do |target_tag|
  puts target_tag.text
end

--output:--
山东济南

Edit: You can actually call text() on the Array, but it will return the concatenated results of the text for each match in the array--which is not something I've ever found useful--but because there is only one match you should have gotten the result 山东济南 . There is nothing in your post that indicates why you didn't get that result.

If you only want a single result from your xpath, ie the first match, then you can use at_xpath() :

target_tag = doc.at_xpath('//*[@id="J-From"]')
puts target_tag.text

--output:--
山东济南