Hi,
On Mon, 2005-06-20 at 00:44 +0200, Jonas Holmberg wrote:
> Hi.
>
> I have a question about the XPath implementation.
> I have tried to get the default attributes from the DTD:s to work with the
> XPath lookups.
> I am very new to libxml, so if there is a very well known answer, I'm
> sorry...
>
> Consider the following document:
>
> <?xml version="1.0"?>
> <!DOCTYPE root SYSTEM "root.dtd" [
> <!ELEMENT elem (#PCDATA)>
> <!ATTLIST elem test CDATA "nothing">
> <!ELEMENT root (elem)>
> ]>
> <root>
> <elem>data1</elem>
> <elem>data2</elem>
> <elem test="something">data3</elem>
> </root>
>
> with this code:
>
> void doXPath(xmlDocPtr doc,xmlChar* xpathExpr)
> {
> xmlXPathContextPtr xpathCtx = xmlXPathNewContext(doc);
> xmlXPathObjectPtr xpathObj = xmlXPathEvalExpression(xpathExpr,xpathCtx);
> xmlNodeSetPtr nodes = xpathObj->nodesetval;
> for (int i = 0; i < nodes->nodeNr; i++) {
> if (nodes->nodeTab[i]->type == XML_ELEMENT_NODE) {
> xmlNodePtr node = nodes->nodeTab[i];
> xmlChar* pProp = xmlGetProp(node,BAD_CAST "test");
> xmlChar* pContent = xmlNodeGetContent(node);
> std::cout << "Node: " << node->name << ", Data: " << pContent << ",
> test = " << pProp << endl;
> xmlFree((void*) pContent);
> xmlFree((void*) pProp);
> }
> }
> xmlXPathFreeObject(xpathObjPtr);
> xmlXPathFreeContext(xpathContextPtr);
> }
>
> doXPath(doc,(xmlChar*) "//root/*");
> gives me:
> Node: elem, Data: data1, test = nothing
> Node: elem, Data: data2, test = nothing
> Node: elem, Data: data3, test = something
>
> So, xmlGetProp works great, giving me the default value of "nothing"
>
> doXPath(doc,(xmlChar*) "//root/[EMAIL PROTECTED]"something\"");
> gives me:
> Node: elem, Data: data3, test = something
>
> Still, as expected.
>
> But.
> doXPath(doc,(xmlChar*) "//root/[EMAIL PROTECTED]"nothing\"");
> gives me no results...
>
>
> Am I wrong in expecting xpath to work with default values, or can anybody
> help me out?
Functions like xmlReadFile [1] take an @options [2] argument. The
XML_PARSE_DTDATTR option-flag will create default attributes
of the DTD in the resulting node tree, thereafter they will be
visible to XPath.
[1] http://xmlsoft.org/html/libxml-parser.html#xmlReadFile
[2] http://xmlsoft.org/html/libxml-parser.html#xmlParserOption
Regards,
Kasimier
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