XPath to get markup between two headings

问题:

I am trying to write a small application to extract content from Wikipedia pages. When I first thought if it, I thought that I could just target divs containing content with XPath, but after looking into how Wikipedia builds their articles, I quickly discovered that wouldn't be so easy. The best way to separate content when I get the page, is to select what's between two sets of h2 tags.

Example: <h2>Title</h2> <div>Some Content</div> <h2>Title</h2>

Here I would want to get the div between the sets of headers. I tried doing this with XPath, but with no luck at all. I am going to look more into XPath because I think that's what I need to use to achieve what I want, but before I look too much into it, I would like to hear what you guys think about it. Is XPath the right way to go or do I have other easier options? I write the application in C# if that makes any difference.

回答1:

Yes, you're on the right track with XPath -- it's ideal for selecting parts of an XML document.

For example, for this XML,

<r>
   <h2>Title A</h2>
   <div>Some Content</div>
   <div>More Content</div>
   <h2>Title B</h2>
</r>

this XPath,

//div[preceding-sibling::h2 = 'Title A' and following-sibling::h2 = 'Title B']

will select this content,

<div>Some Content</div>
<div>More Content</div>

between the two h2 titles, as requested.

---

Update to address OP's self-answer:

For this new XML example,

<div>
    <h2><span>Summary</span></h2>
    <p>Paragraph</p>
    <ul>
        <li>List1</li>
        <li>List2</li>
        <li>List3</li>
    </ul>
    <p>Paragraph</p>

    <h2><span>Location</span></h2>
    <p>Paragraph</p>
</div>

the XPath I provided above can easily be adapted,

//*[preceding-sibling::h2 = 'Summary' and following-sibling::h2 = 'Location']

to select this XML,

<p>Paragraph</p>  
<ul>
   <li>List1</li>
   <li>List2</li>
   <li>List3</li>
</ul>    
<p>Paragraph</p>

as requested.

回答2:

With the help from kjhughes suggestion, I managed to get the code working.

I was unable to make the = 'Text' part work, but replaced it with [text() = 'text']

That alone wasn't enough, as the title of the content I need is location inside a span in a h2 tag, so I had to adapt the XPath a bit more.

This is what I came up with:

//*[preceding-sibling::h2::following-sibling::span[text() = 'Summary'] and following-sibling::h2::following-sibling::span[text() = 'Location']]

I tested it using http://www.xpathtester.com/xpath on this HTML:

<div>
    <h2><span>Summary</span></h2>
    <p>Paragraph</p>
    <ul>
        <li>List1</li>
        <li>List2</li>
        <li>List3</li>
    </ul>
    <p>Paragraph</p>

    <h2><span>Location</span></h2>
    <p>Paragraph</p>
</div>

Which gave me the following result:

<p>Paragraph</p>
<ul>
    <li>List1</li>
    <li>List2</li>
    <li>List3</li>
</ul>
<p>Paragraph</p>