QDomElement

[sabeesh]

Hi,
I am using Qt 4.3.
How can I use QDomElement in Qt.4.3.

I use like this,
I declare a structure in my header file

public:
struct _Configuration {
QDomDocument Document;
QDomElement Root;
QDomElement Defaults;
QDomElement VideoDevices;
QDomElement AudioDevices;
} Configuration;


and in my .cpp file I write the code like this,

QDomElement elem;
elem = Configuration.Document.createElement("videodevice" );
elem.setAttribute("name", name);
elem.setAttribute("node", node);
qDebug()<<" elem is " << elem.isNull();
Configuration.VideoDevices.appendChild(elem);

when I run my program, it display the message like this,

elem is false // elem is Not Null

Calling appendChild() on a null node does nothing.

why this message " Calling appendChild() on a null node does nothing. "
can you help me please for solving this probs.....
Thankyou

[wysota]

The document is probably null as well, hence calling createElement on a null node returns a null element.

[sabeesh]

Hi,
sorry, Not clear. Can you give an example code for this.

[wysota]

Example code of what?

Did you have a look at QDomDocument docs?

[jpn]

Here is an example straight from QDomDocument docs (detailed description part):

QDomDocument doc("MyML");
QDomElement root = doc.createElement("MyML");
doc.appendChild(root);
 
QDomElement tag = doc.createElement("Greeting");
root.appendChild(tag);
 
QDomText t = doc.createTextNode("Hello World");
tag.appendChild(t);
 
QString xml = doc.toString();

QDomDocument doc("MyML");
QDomElement root = doc.createElement("MyML");
doc.appendChild(root);

QDomElement tag = doc.createElement("Greeting");
root.appendChild(tag);

QDomText t = doc.createTextNode("Hello World");
tag.appendChild(t);

QString xml = doc.toString();

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You cannot do it like this:

QDomElement element;
element.appendChild(child);

QDomElement element;
element.appendChild(child);

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because the element exists no where. This is exactly what you do with "Configuration.VideoDevices". Use the QDomDocument::createElement() or its friends to construct elements.