How parse XML empty node with Libxml2? In C

Question

I have a problem getting empty nodes with libxml2 in C. The problem is the node is like <node /> and the lib recognizes it in the xPath, but if i try to put more nodes inside that him the lib don't do it.

Here the code i'm using to parse document:

xmlDocPtr xApiXmlUtilsGetDocFile(char *pcDocName)
{
    xmlDocPtr xDoc;
    xDoc = xmlReadFile(pcDocName,"utf-8",XML_PARSE_NOBLANKS);

    if (xDoc == NULL)
    {
        fprintf(stderr, "Document not parsed successfully. \n");
        return NULL;
    }
    TRACE("Document parsed successfully.");
    return xDoc;
}

Here the code to add nodes (put correctly if the node is something like <node></node> ):

int lApiAddElement(xmlDocPtr xDoc, char* pcXPATHBrother, char* pcChildName, char* pcChildContent, AddType_t xAddType)
{
    xmlXPathObjectPtr xPathObj;

    /* Create xpath evaluation context */
    xPathObj = xApiXmlUtilsGetNodeSet(xDoc, BAD_CAST pcXPATHBrother);
    if( xPathObj == NULL )
    {
        return -1;
    }

    // Get the div node
    xmlNodeSetPtr xNodes = xPathObj->nodesetval;
    xmlNodePtr xDivNode = xNodes->nodeTab[0];

    xmlNodePtr xDivChildNode = xDivNode; //->xmlChildrenNode;
    if( (xAddType == eAddChildPrev) || (xAddType == eAddChildNext) )
    {
        xDivChildNode = xDivNode->xmlChildrenNode;
    }

    xmlNodePtr xHeadingNode = xmlNewNode(0, BAD_CAST pcChildName);
    xmlNodePtr xHeadingChildNode = xmlNewText(BAD_CAST pcChildContent);
    xmlAddChild(xHeadingNode, xHeadingChildNode);

    // Add the new element to the existing tree after the text content
    if( (xAddType == eAddPrev) || (xAddType == eAddChildPrev) )
    {
        xmlAddPrevSibling(xDivChildNode, xHeadingNode);
    }
    else
    {
        if( xAddType == eAddChildNext )
        {
            xmlAddSibling(xDivChildNode, xHeadingNode);
        }
        else
        {
            xmlAddNextSibling(xDivChildNode, xHeadingNode);
        }
    }

    //if you want to display the result
    xmlDocDump(stdout, xDoc);

    return 0;
}

OBS.: I don't have control over the generation of nodes, like that answer suggests.

How to convert <node/> to <node></node> with libxml (converting empty elements to start-end tag pairs)

So, how add nodes to a empty node with libxml2?

EDIT:

Debugging my function a little i find that in the line of i get the child:

xDivChildNode = xDivNode->xmlChildrenNode;

if the node is <node /> then the chindremNode will be null, so how to guarantee that not even return null?

thanks.

Answer 1

Based on your debug log, you need to replace

xmlNodePtr xDivChildNode = xDivNode; //->xmlChildrenNode;
if( (xAddType == eAddChildPrev) || (xAddType == eAddChildNext) )
{
    if (xDivNode->xmlChildrenNode == NULL){
        xmlNodeAddContent(xDivNode,BAD_CAST " ");//avoiding empty nodes, puting content in the node.
    }
    xDivChildNode = xDivNode->xmlChildrenNode;
}

To make sure the libxml don't add an empty node to your xml file.