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POXPath and negation searches
 

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  1. POXPath and negation searches
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    <p>I have the following code sample in an <code>xmlns</code> root:</p> <pre><code>&lt;ol class="stan"&gt; &lt;li&gt;Item one.&lt;/li&gt; &lt;li&gt; &lt;p&gt;Paragraph one.&lt;/p&gt; &lt;p&gt;Paragraph two.&lt;/p&gt; &lt;/li&gt; &lt;li&gt; &lt;pre&gt;Preformated one.&lt;/pre&gt; &lt;p&gt;Paragraph one.&lt;/p&gt; &lt;/li&gt; &lt;/ol&gt; </code></pre> <p>I would like to perform a different operation on the first item in <code>&lt;li&gt;</code> depending on the type of tag it resides in, or no tag, i.e. the first <code>&lt;li&gt;</code> in the sample.</p> <hr> <p>EDIT:</p> <p>My logic in pursuing the task turns out to be incorrect.</p> <ol> <li>How do I query a <code>&lt;li&gt;</code> that has no descendants as in the first list item?</li> </ol> <p>I tried negation:</p> <pre><code>@doc.xpath("//xmlns:ol[@class='stan']//xmlns:li/xmlns:*[1][not(p|pre)]") </code></pre> <p>That gives me the exact opposite for what I think I am asking for.</p> <p>I think I am making the expression more complicated since I can't find the right solution.</p> <hr> <p>UPDATE:</p> <p>Navin Rawat has answered this one in the comments. The correct code would be:</p> <pre><code>@doc.xpath("//xmlns:ol[@class='stan']/xmlns:li[not(xmlns:*)]") </code></pre> <hr> <p>CORRECTION:</p> <p>The correct question involves both an XPath search and a Nokogiri method.</p> <p>Given the above <code>xhtml</code> code, how do I search for first descendant using <code>xpath</code>? And how do I use <code>xpath</code> in a conditional statement, e.g.:</p> <pre><code>@doc.xpath("//xmlns:ol[@class='stan']/xmlns:li").each do |e| if e.xpath("e has no descendants") perform task elsif e.xpath("e first descendant is &lt;p&gt;") perform second task elsif e.xpath("e first descendant is &lt;pre&gt;") perform third task end end </code></pre> <p>I am not asking for complete code. Just the part in parenthesis in the above <code>Nokogiri</code> code.</p>
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    1. USthe Tin Man
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    1. COTry to use xmlns:li[not(xmlns:*)]
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      1. USNavin Rawat
    2. COThanks @NavinRawat that answered part of the question. I made corrections as my logic in pursuing the problem was flawed.
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    3. CODon't bother using `<del>` tags to mark up things you changed. We can look at the edit history if anything is confusing. Similarly, you don't have to put a chain of "EDIT:", "CORRECTION:" and similar tags unless they're really necessary. Keep your question clearly stated and provide the needed information up front and we can figure it out pretty easily.
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      1. USthe Tin Man
 

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