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POHow to apply successively two xpath expressions with libxml?
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2009-01-29T17:23:30.973
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2013-05-28T11:50:38.867
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David Segonds
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To sum up, i'm a totally beginner in libxml and I have to use an existing source code. The main idea is to apply a first xpath expression to extract a set of nodes from an xml file. Then, for each node, the second xpath expression shall be applied to extract some values. Existing source code is: <pre><code>int xt_parseXmlResult(xmlDocPtr doc, const char *xpath, assoc_arrayc_t expr, arrayc_t *result) { xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc); // Register namespaces ... /* * Evaluate main xpath expression */ xmlXPathObjectPtr xpathNodes = xmlXPathEvalExpression((xmlChar *)xpath, xpathCtx); /* * Now we apply the xpath expressions on each node returned by the first xpath request */ // First loop is on the XML document as we have to create a new context each // time we change the document int nbDocs = xpathNodes->nodesetval->nodeNr; for (row = 0; row < nbDocs; row++) { xmlXPathContextPtr subCtx = xmlXPathNewContext(doc); // Register namespaces ... // Update context to use the nodeset related to this row subCtx->node = xpathNodes->nodesetval->nodeTab[row]; for (col = 0; col < expr.nbItems; col++) { // Evaluate expression xpathRows = xmlXPathEvalExpression((xmlChar *)expr.itemList[col].val, subCtx); result->data[(row + 1) * result->nbCols + col] = strdup((char *)xmlXPathCastToString(xpathRows)); xmlXPathFreeObject(xpathRows); } xmlXPathFreeContext(subCtx); subCtx = NULL; } xmlFreeDoc(doc); xmlXPathFreeContext(xpathCtx); xmlXPathFreeObject(xpathNodes); return 0; } </code></pre> I think that the problem comes from this line <pre><code> // Update context to use the nodeset related to this row subCtx->node = xpathNodes->nodesetval->nodeTab[row]; </code></pre> Because the second xpath expression is applied from the root of the xml file, not the root of each node. Any idea on how to do such thing?
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<xpath><libxml2>
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How to apply successively two xpath expressions with libxml?
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