How to let XPathExtractor extract xml element only if Http response code is 200?

In my JMeter test plan, I have a HttpRequest, I want to extract the link from its response only if the response code is 200. I can add an XPathExtractor post processor under HttpRequest and it works.

But I want to have an IfCondition first so that the extractor won't try to work on invalid content. But the IfController can't be added as a postprocessor.

Maybe I can have a BeanShell sampler to do it but I don't know how to use XPathExtractor in BeanShell.

Solution

"Short and easy" way - use an additional Sampler

Add If Controller after the HTTP Request
Use ${JMeterThread.last_sample_ok} as "Condition"
Put Beanshell Sampler under the If Controller

Use the following code in Beanshell Sampler "Script" area:

SampleResult.setResponseData(ctx.getPreviousResult().getResponseData());

Put XPath Extractor as a child of the Beanshell Sampler

The above Beanshell script will return the same response as preceding HTTP Request sampler

"Long and hard" way - extract XPath directly in Beanshell.

Put Beanshell PostProcessor instead of XPath Extractor

Use the following script as a reference:

import org.apache.jmeter.util.PropertiesBasedPrefixResolver;
import org.apache.jmeter.util.XPathUtil;
import org.apache.xpath.XPathAPI;
import org.apache.xpath.objects.XObject;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;


InputStream in = new ByteArrayInputStream(prev.getResponseData());
boolean useNameSpace = false;
boolean isTolerant = true;
boolean isQuiet = true;
boolean showWarnings = true;
boolean reportErrors = true;
boolean isXML = false;
boolean isDownloadDTDs = false;


if (prev.isResponseCodeOK()) {

    InputStream in = new ByteArrayInputStream(prev.getResponseData());
    boolean useNameSpace = false;
    boolean isTolerant = true;
    boolean isQuiet = true;
    boolean showWarnings = true;
    boolean reportErrors = true;
    boolean isXML = false;
    boolean isDownloadDTDs = false;


    String query = "//a[text()='JMeter FAQ (Wiki)']";
    List matchStrings = new ArrayList();
    //matchStrings.add("-1");
    boolean returnFragment = false;


    Document doc = XPathUtil.makeDocument(in, false, false, useNameSpace, isTolerant, isQuiet, showWarnings, reportErrors
                , isXML, isDownloadDTDs);
    String val = null;
    XObject xObject = XPathAPI.eval(doc, query, new PropertiesBasedPrefixResolver(doc.getDocumentElement());
    int objectType = xObject.getType();
    if (objectType == xObject.CLASS_NODESET) {
        NodeList matches = xObject.nodelist();
        int length = matches.getLength();

        for (int i = 0; i < length; ++i) {
            Node match = matches.item(i);
            if (match instanceof Element) {
                if (returnFragment) {
                    StringWriter sw = new StringWriter();

                    Transformer t = TransformerFactory.newInstance().newTransformer();
                        t.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
                    t.transform(new DOMSource(match), new StreamResult(sw));

                    val = sw.toString();
                } else {
                    Node firstChild = match.getFirstChild();
                    if (firstChild != null) {
                        val = firstChild.getNodeValue();
                    } else {
                        val = match.getNodeValue();
                    }
                }
            } else {
                val = match.getNodeValue();
            }

            matchStrings.add(val);
        }
    } else if (objectType != xObject.CLASS_NULL && objectType != xObject.CLASS_UNKNOWN && objectType != xObject.CLASS_UNRESOLVEDVARIABLE) {
        val = xObject.toString();
        matchStrings.add(val);
    } else {
        log.warn("Unexpected object type: " + xObject.getTypeString() + " returned for: " + query);
    }


    for (String match : matchStrings) {
        log.info("Match -----> " + match);
    }
}

See How to Use BeanShell: JMeter's Favorite Built-in Component guide for more information on using Beanshell in JMeter scripts