How to get line number from XML file when using with QDomDocument?

[nn26]

Hello,

suppose we have xml file like this,

<string>
        <Data>
              <Name>abc</Name>
              <Number>123</Number>
              <Address>kjl</Address>
        </Data>
        <Data>
              <Name>zutr</Name>
              <Number>897</Number>
              <Address>bgfs</Address>
        </Data>
</string>

when using with QDomDocument (or after parsing into QDomElement, QDomNode)

how to get line number of any tag like, e.x. <Address>kjl</Address> ?

Thanks.

[mrjj]

Hi
I dont think you can. :/ see @Bonnie post
Line numbers are mostly used for parsing errors
but i have not seen it associated with actual
object.

Can i ask why you need line numbers ?

[Bonnie]

Maybe you could check this

int QDomNode::lineNumber() const

For nodes created by QDomDocument::setContent(), this function returns the line number in the XML document where the node was parsed. Otherwise, -1 is returned.
This function was introduced in Qt 4.1.

[nn26]

@mrjj I am comparing two XML files. After checking from root element to each child nodes by using QdomDocument, QDomElement, QDomNode in each loop ,

I want to also print line number from which that difference came.

[mrjj]

@nn26
Ok in that way. then i see why line numbers is important.

[JonB]

@nn26
@Bonnie 's solution is the way to go.

[nn26]

@Bonnie It is not useful. It will only show parsing error. like this example, if <string> tag is not ended with </string>.

<string>
        <Data>
              <Name>abc</Name>
              <Number>123</Number>
              <Address>kjl</Address>
        </Data>
        <Data>
              <Name>zutr</Name>
              <Number>897</Number>
              <Address>bgfs</Address>
        </Data>
<string>

[nn26]

@JonB no, it is only useful for checking one time parsing error.

[mrjj]

@nn26

so you checked ?
Its not set for a Node unless there has been an error ?

[JonB]

@nn26

It is not useful. It will only show parsing error.

That is not what the docs state. I don't see any indication in the source code indicating it is only set on errors. As per @mrjj, have you tried it?

[nn26]

@JonB yes I have tried it. As I said, It is completely different thing (lineNumber()) to check error, line number and column when parsing XML file with setContent(). Here, my requirement is different.

[Bonnie]

@nn26 I think you've misunderstood something.
This is not the int *errorLine in QDomDocument::setContent function.
You see? when you have parse errors, you can't get a valid QDomNode...
I've tried your xml text in the top post, this function works well.

    QDomDocument doc;
    if(doc.setContent(text.toUtf8())) {
        auto element = doc.documentElement().firstChildElement();
        qDebug() << element.tagName() << element.lineNumber() << element.columnNumber() << endl;
    }

the output is

"Data" 2 14 

[nn26]

@Bonnie thank you for the answer.

doc.documentElement().firstChildElement()

this will give output of <Data> in line 2, but how to get line number of another <Data> tag when working in loop?

       ```

QDomDocument doc;
QDomElement root = doc.documentElement();

	  

            

for example when working with loop after getting root  from above code,

      

       

QDomNode node = root.firstChild();

    while (!node.isNull()) {
	   QDomElement element = node.toElement();
              **qDebug()<< root.toElement().firstChildElement().lineNumber();**
               
	   ....
               ....
             node = node.nextSibling();
             
      }

so, Here root.toElement().firstChildElement().lineNumber() is giving correct line number in first iteration but for other iteration it is repeating same line number which is not correct.

[JonB]

@nn26
You want to know about the line number of each node, not always of the root's first element, don't you? So node.lineNumber() (or element.lineNumber()).

[Bonnie]

@nn26 Seems your question is how to iterate.

auto element = doc.documentElement().firstChildElement();
while(!element.isNull()) {
    qDebug() << element.tagName() << element.lineNumber() << endl;
    element = element.nextSiblingElement();
}

Here you can get all of the Datas

[nn26]

@Bonnie @JonB @mrjj thanks for the answer. Now, I am getting correct line number with node.lineNumber(). I am doing things recurcively that's causing confusion. for root It can be obtained by doc.firstChildElement().lineNumber() and for each other child node, node.lineNumber().