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POXPath: limit scope of result set
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copied!<p>Given the XML</p> <pre><code><a> <c> <b id="1" value="noob"/> </c> <b id="2" value="tube"/> <a> <c> <b id="3" value="foo"/> </c> <b id="4" value="goo"/> <b id="5" value="noob"/> <a> <b id="6" value="near"/> <b id="7" value="bar"/> </a> </a> </a> </code></pre> <p>and the Xpath 1.0 query</p> <pre><code>//b[@id=2]/ancestor::a[1]//b[@value="noob"] </code></pre> <p>The Xpath above returns both node ids 1 and 5. The goal is to limit the result to just node id=1 since it is the only <code>@value="noob"</code> element that is a descendant of the same <code><a></code> that (<code>//b[@id=2]</code>) is also a descendant of.</p> <p>In other words, "Find all <strong>b</strong> elements who's value is "noob" that are descendants of the <strong>a</strong> element which also has a descendant whose id is 2, but is not the descendant of any other <strong>a</strong> element". How's that for convoluted? In practice the id number and values would be variable and there would hundreds of node types.</p> <p>If the id=2, we would expect to return element id=1 not id=5 since it is contained in another a element. If the id=4, we would expect to return id=5, but not id=1 since it is not in the first ancestor a element as id=4.</p> <p><strong>Edit:</strong> Based on the comments of Dimitre and Alejandro, I found <a href="http://sweatte.wordpress.com/syntax/xml-tips/xpath-tips/" rel="nofollow">this</a> helpful blog entry explaining the use of count() with the | union operator as well as some other excellent tips. </p>

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