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POHtmlUnit and XPath: DOMNode.getByXPath only works on HtmlPage?
 

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  1. POHtmlUnit and XPath: DOMNode.getByXPath only works on HtmlPage?
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    <p>I'm trying to parse <a href="http://living.scotsman.com/sectionhome.aspx?sectionID=7063" rel="nofollow noreferrer">a page</a> with links to articles whose important content looks like this:</p> <pre><code>&lt;div class="article"&gt; &lt;h1 style="float: none;"&gt;&lt;a href="performing-arts"&gt;Performing Arts&lt;/a&gt;&lt;/h1&gt; &lt;a href="/performing-arts/EIF-theatre-review-Sin-Sangre.6517348.jp"&gt; &lt;span class="mth3"&gt; &lt;span id="wctlMiniTemplate1_ctl00_ctl00_ctl01_WctlPremiumContentIcon1"&gt; &lt;/span&gt; EIF theatre review: Sin Sangre | The Man Who Fed Butterflies | Caledonia | Songs Of Ascension | Vieux Carré | The Gospel At Colonus &lt;/span&gt; &lt;span class="mtp"&gt;The EIF&amp;#39;s theatre programme wasn&amp;#39;t as far-reaching as it could have been, but did find an exoticism in the familiar, writes Mark Fisher &lt;/span&gt; &lt;/a&gt; &lt;/div&gt; </code></pre> <p>Here is a minimal scraping case in Java using HtmlUnit and XPath (imports removed for brevity):</p> <pre><code>public class MinimalTest { public static void main(String[] args) throws Exception { WebClient client = new WebClient(); client.setJavaScriptEnabled(false); client.setCssEnabled(false); System.out.println("Fetching front page"); HtmlPage frontPage = client.getPage("http://living.scotsman.com/sectionhome.aspx?sectionID=7063"); List&lt;ArticleInfo&gt; articleInfos = extractArticleInfo(frontPage); for (ArticleInfo info : articleInfos) { System.out.println("Title: " + info.getTitle()); System.out.println("Intro: " + info.getFirstPara()); System.out.println("Link: " + info.getLink()); } } @SuppressWarnings("unchecked") // xpath returns List&lt;?&gt; private static List&lt;ArticleInfo&gt; extractArticleInfo(HtmlPage frontPage) { System.out.println("Extracting article links"); List&lt;HtmlDivision&gt; articleDivs = (List&lt;HtmlDivision&gt;) frontPage.getByXPath("//div[@class='article']"); System.out.println(String.format("Found %d articles", articleDivs.size())); List&lt;ArticleInfo&gt; articleLinks = new ArrayList&lt;ArticleInfo&gt;(articleDivs.size()); for (HtmlDivision div : articleDivs) { articleLinks.add(ArticleInfo.constructFromArticleDiv(div)); } return articleLinks; } private static class ArticleInfo { private final String title; private final String link; private final String firstPara; public ArticleInfo(final String link, final String title, final String firstPara) { this.link = link; this.title = title; this.firstPara = firstPara; } public static ArticleInfo constructFromArticleDiv(final HtmlDivision div) { String link = ((DomText) div.getFirstByXPath("//a/@href/text()")).asText(); String title = ((DomText) div.getFirstByXPath("//span[@class='mth3']/text()")).asText(); String firstPara = ((DomText) div.getFirstByXPath("//span[@class='mtp']/text()")).asText(); return new ArticleInfo(link, title, firstPara); } public String getTitle() { return title; } public String getFirstPara() { return firstPara; } public String getLink() { return link; } } } </code></pre> <p>Output I expect:</p> <pre><code>Title: EIF theatre review: Sin Sangre | The Man Who Fed Butterflies | Caledonia | Songs Of Ascension | Vieux Carré | The Gospel At Colonus Intro: The EIF's theatre programme wasn't as far-reaching as it could have been, but did find an exoticism in the familiar, writes Mark Fisher Link: http://living.scotsman.com/performing-arts/EIF-theatre-review-Sin-Sangre.6517348.jp </code></pre> <p>What I get:</p> <pre><code>Fetching front page Extracting article links Found 24 articles Exception in thread "main" java.lang.NullPointerException at com.allthefestivals.app.crawler.MinimalTest$ArticleInfo.constructFromArticleDiv(MinimalTest.java:68) at com.allthefestivals.app.crawler.MinimalTest.extractArticleInfo(MinimalTest.java:50) at com.allthefestivals.app.crawler.MinimalTest.main(MinimalTest.java:30) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:115) </code></pre> <p>Calling <code>getByXPath</code> works fine on a <code>HtmlPage</code> but seems to return nothing on any other <code>HtmlElement</code>. What's wrong? Is this a bug or implementation gap in HtmlUnit, or am I missing something subtle about XPath syntax?</p> <p>Related question whose solution didn't work for me: <a href="https://stackoverflow.com/questions/2980792/xpath-relative-to-given-element-in-htmlunit-groovy">XPath _relative_ to given element in HTMLUnit/Groovy?</a></p>
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    1. USIain Samuel McLean Elder
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    1. COyou have a typo in `@/class`. Beside that, if this questions is not about XPath expressions, it should be tagged as `xpathengines` because refer specific method to call xpath engine.
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    2. COThanks for pointing out the typo. It might be a question about XPath expressions. I don't know. Did they look like they should work to you?
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      1. USIain Samuel McLean Elder
 

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