The XDK C++ XML APIs need an XML context from which to operate. When using the C APIs this is done by calling OCIXmlDbInitXmlCtx() and then casting its return context to xmlnode. This can’t be done directly in C++; therefore, the following function wraps the C one to produce a C++ context you can use with the C++ XDK APIs.
sb4 ociapi::select_from_doc(OCIXMLType* xml, text *xpathexpr){
boolean result = 0;
OCIXMLType *newxml = (OCIXMLType *) 0;
OCIXMLType *xmltran = (OCIXMLType *) 0;
sword status = 0;
/* For XML C++ APIs */
OCIDuration dur = OCI_DURATION_SESSION;
struct xmlctx *xctx = (xmlctx *)0;
xmldocnode *doc = (xmldocnode *)0;
ocixmldbparam params[1];
/* Get an XML C and C++ context */
params[0].name_ocixmldbparam = XCTXINIT_OCIDUR;
params[0].value_ocixmldbparam = &dur;
xctx = OCIXmlDbInitXmlCtx( envhp, svchp, errhp, params, 1);
CXmlCtx* cxctxp = new CXmlCtx( xctx);
/* convert the xmltype value to C++ DocumentRef */
doc = (xmldocnode *) xml;
DOMImplRef< CXmlCtx, xmlnode>
impl_ref( cxctxp, new DOMImplementation< xmlnode>( FALSE));
DocumentRef< xmlnode>* doc_refp = impl_ref.formDocument( (xmlnode*)doc);
/* test xml unified C APIs */
if (doXPath< CXmlCtx, xmlnode>( cxctxp, *doc_refp, (char*)xpathexpr)) {
printf("FAILED: doXPath()\n");
return OCI_ERROR;
}
/* free the statement handle */
if (stmthp) {
OCIHandleFree((dvoid *)stmthp, OCI_HTYPE_STMT);
}
/* free the xmlctx */
OCIXmlDbFreeXmlCtx(xctx);
/* free xml instances using OCIObjectFree */
if (newxml &&
(status = OCIObjectFree(envhp, errhp, (dvoid *) newxml,
(ub2)OCI_OBJECTFREE_FORCE))) {
printf("FAILED: OCIObjectFree()\n");
checkerr(errhp, status);
return OCI_ERROR;
}
return OCI_SUCCESS;
}
The OCIXmlDbInit() function returns the C context, xctx, which is then passed to the CXmlCtx() constructor to return the C++ context, cxctxp. This context can then be used to create the C++ DocumentRef, doc_refp, that points to the XOB DOM and can be used with the C++ XDK APIs.