libxml2 and XPath traversing children and siblings in ANSI C - c

Question

I have done a fair bit of XML stuff in Perl and now I need to do it in ANDI C for a project. Here's the code I wrote with a snippet of the XML. I have had success to a degree, but am having problems with getting siblings, I am sure it's super easy but I just can't get it. There is two functions, one that simply gets the node set (copied directly from xmlsoft.org). The second function is mine.
xmlXPathObjectPtr getnodeset (xmlDocPtr doc, xmlChar *xpath){
xmlXPathContextPtr context;
xmlXPathObjectPtr result;
context = xmlXPathNewContext(doc);
if (context == NULL) {
printf("Error in xmlXPathNewContext\n");
return NULL;
}
result = xmlXPathEvalExpression(xpath, context);
xmlXPathFreeContext(context);
if (result == NULL) {
printf("Error in xmlXPathEvalExpression\n");
return NULL;
}
if(xmlXPathNodeSetIsEmpty(result->nodesetval)){
xmlXPathFreeObject(result);
printf("No result\n");
return NULL;
}
return result;
}
void reader(xmlDocPtr xmlDoc, char *xpath)
{
xmlXPathObjectPtr xpathresult;
xmlNodeSetPtr node;
xmlNodeSetPtr node2;
xmlChar *title;
int cnt;
// parse feed in memory to xml object
doc = xmlReadMemory(xmlDoc,strlen(xmlDoc),"noname.xml",NULL,0);
if (!doc) criterr("Error parsing xml document");
// get xpath node set (ttn retrieves the value from the token table)
xpathresult = getnodeset(doc, ( xmlChar * ) xpath);
if (xpathresult) {
node = xpathresult->nodesetval;
printf("Content-type: text/html\n\n");
for (cnt=0;cnt<node->nodeNr; cnt++) {
title = xmlNodeListGetString(doc, node->nodeTab[cnt]->xmlChildrenNode,1);
printf("%d) title= %s<br/>\n",cnt,title);
xmlFree(title);
}
xmlXPathFreeObject(xpathresult);
xmlFreeDoc(doc);
xmlCleanupParser();
} else {
criterr("Xpath failed");
}
xmlFreeDoc(doc);
criterr("Success");
}
and the xml snippet
<item>
<title>this is the title</title>
<link>this is the link</link>
<description>this is the description</description>
</item>
if I use an XPath like //item/title I get all the titles, but what I really want is to get the item and then in the node->nodeNr loop, be able to get the title, link and description easily as I have 100's of 'item' blocks, I'm just not sure how to get the children or siblings of that block easily.

Answer 1

Use xmlNextElementSibling. How does one locate it? Go to Tree API, search for sibling.
And this is your loop now getting also the link.
for (cnt=0;cnt<node->nodeNr; cnt++) {
xmlNodePtr titleNode = node->nodeTab[cnt];
// titleNode->next gives empty text element, so better:
xmlNodePtr linkNode = xmlNextElementSibling(titleNode);
title = xmlNodeListGetString(doc, titleNode->xmlChildrenNode,1);
link = xmlNodeListGetString(doc, linkNode->xmlChildrenNode,1);
printf("%d) title= %s<br/>, link=%s\n",cnt,title,link);
xmlFree(title);
xmlFree(link);
}
titleNode->next may also be made to point the link, see how to get these XML elements with libxml2?.
And getting children? xmlFirstElementChild and loop while node->next.