Remove element of xml

**VitaliBR** · 3rd February 2011, 23:29

xml Code:

Switch view

<lista>
 <client>
  <dns>google.com.br</dns>
  <phone>(19)3632-9244</phone>
  <name>Google</name>
 </client>
 <client>
  <dns>uol.com.br</dns>
  <phone>(16)3307-5496</phone>
  <name>Uol</name>
 </client>
 <client>
  <dns>terra.com.br</dns>
  <phone>(21)3368-0422</phone>
  <name>Terra</name>
 </client>
</list>

<lista>
 <client>
  <dns>google.com.br</dns>
  <phone>(19)3632-9244</phone>
  <name>Google</name>
 </client>
 <client>
  <dns>uol.com.br</dns>
  <phone>(16)3307-5496</phone>
  <name>Uol</name>
 </client>
 <client>
  <dns>terra.com.br</dns>
  <phone>(21)3368-0422</phone>
  <name>Terra</name>
 </client>
</list>

To copy to clipboard, switch view to plain text mode

I wonder how I can delete everything between the tag <client> </client> choosing the name,
eg:
I would like to delete the customer information Google:

xml Code:

Switch view

<client>
  <dns>google.com.br</dns>
  <phone>(19)3632-9244</phone>
  <name>Google</name>
 </client>

<client>
  <dns>google.com.br</dns>
  <phone>(19)3632-9244</phone>
  <name>Google</name>
 </client>

To copy to clipboard, switch view to plain text mode

Thanks

**stampede** · 4th February 2011, 05:43

Quick and dirty solution could be to use regular expressions.
Yours could look like this (pseudocode):

Qt Code:

Switch view

<client>/*whatever*/<name>/*maybe whitespaces*/ClientToDelete/*maybe whitespaces*/</name>/*whatever*/</client>

<client>/*whatever*/<name>/*maybe whitespaces*/ClientToDelete/*maybe whitespaces*/</name>/*whatever*/</client>

To copy to clipboard, switch view to plain text mode

Don't forget to set it for minimal match, it'll eat up all your xml otherwise (if it founds ClientToDelete).

**helloworld** · 4th February 2011, 05:48

It would help if you explained a bit how you are parsing the document; i.e., if you are using SAX, DOM, or some other parser.

**VitaliBR** · 4th February 2011, 10:56

Originally Posted by helloworld

It would help if you explained a bit how you are parsing the document; i.e., if you are using SAX, DOM, or some other parser.

lol Sorry guy

I'm using the DOM, see:

Qt Code:

Switch view

QString arquivo = "List.xml";
 
	QFile file(arquivo);
	QDomDocument doc( "List" );
 
	//Checking if file exists
	if(!file.exists())
	{
		QMessageBox::information(0,tr("Critical Error"),tr("The file %1 does not exist! \ nPlease try to register an account!!").arg(arquivo));
		this->close();
	}
 
	//Checking if the file can be read and written
	if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
	{
		QMessageBox::information(0,tr("Critical Error"),tr("Failed to open file  %1!").arg(arquivo));
		file.close();
		this->close();
	}
 
	//Getting the contents of the old xml
	doc.setContent(&file);
	file.close();

QString arquivo = "List.xml";
				
	QFile file(arquivo);
	QDomDocument doc( "List" );
					
	//Checking if file exists
	if(!file.exists())
	{
		QMessageBox::information(0,tr("Critical Error"),tr("The file %1 does not exist! \ nPlease try to register an account!!").arg(arquivo));
		this->close();
	}

	//Checking if the file can be read and written
	if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
	{
		QMessageBox::information(0,tr("Critical Error"),tr("Failed to open file  %1!").arg(arquivo));
		file.close();
		this->close();
	}
		
	//Getting the contents of the old xml
	doc.setContent(&file);
	file.close();

To copy to clipboard, switch view to plain text mode

Thanks

Added after 36 minutes:

I changed the structure of my XML:

Qt Code:

Switch view

<list>
 <client name="Google">
  <dns>google.com.br</dns>
  <phone>+5521XXXXXXXX</phone>
 </client>
 <client name="Hotmail">
  <dns>hotmail.com</dns>
  <phone>+5535XXXXXXXX</phone>
 </client>
</list>

<list>
 <client name="Google">
  <dns>google.com.br</dns>
  <phone>+5521XXXXXXXX</phone>
 </client>
 <client name="Hotmail">
  <dns>hotmail.com</dns>
  <phone>+5535XXXXXXXX</phone>
 </client>
</list>

To copy to clipboard, switch view to plain text mode

I created a method to delete, but is not working:

Qt Code:

Switch view

void Remove::RemoveGroup(QDomDocument *twmDomDocument, QString theGroupName )
{
	QDomNodeList domTwm = twmDomDocument->elementsByTagName( "client" );
 
	if ( !domTwm.isEmpty() )
	{
		for ( uint i = 0; i < domTwm.length(); i++ )
		{
			if ( domTwm.at(i).toElement().attribute( "name" ) == theGroupName )
			{
				twmDomDocument->removeChild( domTwm.at(i) );
			}
		}
	}
}

void Remove::RemoveGroup(QDomDocument *twmDomDocument, QString theGroupName )
{
	QDomNodeList domTwm = twmDomDocument->elementsByTagName( "client" );

	if ( !domTwm.isEmpty() )
	{
		for ( uint i = 0; i < domTwm.length(); i++ )
		{
			if ( domTwm.at(i).toElement().attribute( "name" ) == theGroupName )
			{
				twmDomDocument->removeChild( domTwm.at(i) );
			}
		}
	}
}

To copy to clipboard, switch view to plain text mode

Qt Code:

Switch view

void Remove::Remover()
{
	RemoveGroup(&leXml(),"Google");
}
 
QDomDocument Remove::leXml()
{
        QString arquivo = "List.xml";
 
	QFile file(arquivo);
	QDomDocument doc( "List" );
 
	//Checking if file exists
	if(!file.exists())
	{
		QMessageBox::information(0,tr("Critical Error"),tr("The file %1 does not exist! \ nPlease try to register an account!!").arg(arquivo));
		this->close();
	}
 
	//Checking if the file can be read and written
	if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
	{
		QMessageBox::information(0,tr("Critical Error"),tr("Failed to open file  %1!").arg(arquivo));
		file.close();
		this->close();
	}
 
	//Getting the contents of the old xml
	doc.setContent(&file);
	file.close();
	return doc;
}

void Remove::Remover()
{
	RemoveGroup(&leXml(),"Google");
}

QDomDocument Remove::leXml()
{
        QString arquivo = "List.xml";
				
	QFile file(arquivo);
	QDomDocument doc( "List" );
					
	//Checking if file exists
	if(!file.exists())
	{
		QMessageBox::information(0,tr("Critical Error"),tr("The file %1 does not exist! \ nPlease try to register an account!!").arg(arquivo));
		this->close();
	}

	//Checking if the file can be read and written
	if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
	{
		QMessageBox::information(0,tr("Critical Error"),tr("Failed to open file  %1!").arg(arquivo));
		file.close();
		this->close();
	}
		
	//Getting the contents of the old xml
	doc.setContent(&file);
	file.close();
	return doc;
}

To copy to clipboard, switch view to plain text mode

Why?

**VitaliBR** · 4th February 2011, 19:14

anyone?

**stampede** · 4th February 2011, 19:22

A little suggestion:

Qt Code:

Switch view

void Remove::RemoveGroup(QDomDocument *twmDomDocument, QString theGroupName )
{
	QDomNodeList domTwm = twmDomDocument->elementsByTagName( "client" );
        qDebug() << "start remove: " << theGroupName;
	if ( !domTwm.isEmpty() )
	{
                qDebug() << "not empty... length: " << domTwm.length();
		for ( uint i = 0; i < domTwm.length(); i++ )
		{
                        qDebug() << "processing " << i << " -> " << domTwm.at(i).toElement().attribute( "name" );
			if ( domTwm.at(i).toElement().attribute( "name" ) == theGroupName )
			{
                                qDebug() << "removing";
				twmDomDocument->removeChild( domTwm.at(i) );
			}
		}
	}
}

void Remove::RemoveGroup(QDomDocument *twmDomDocument, QString theGroupName )
{
	QDomNodeList domTwm = twmDomDocument->elementsByTagName( "client" );
        qDebug() << "start remove: " << theGroupName;
	if ( !domTwm.isEmpty() )
	{
                qDebug() << "not empty... length: " << domTwm.length();
		for ( uint i = 0; i < domTwm.length(); i++ )
		{
                        qDebug() << "processing " << i << " -> " << domTwm.at(i).toElement().attribute( "name" );
			if ( domTwm.at(i).toElement().attribute( "name" ) == theGroupName )
			{
                                qDebug() << "removing";
				twmDomDocument->removeChild( domTwm.at(i) );
			}
		}
	}
}

To copy to clipboard, switch view to plain text mode

Whats the output ?

------------------------------
Wait a minute, now I've looked how you are calling your methods. This is not good:

Qt Code:

Switch view

RemoveGroup(&leXml(),"Google");

RemoveGroup(&leXml(),"Google");

To copy to clipboard, switch view to plain text mode

Dont pass temporary values by pointer or reference, whats the point - leXml() returns a QDomDocument which may be modified by RemoveGroup(), but you cant access it anymore. This is a mess. Try this:

Qt Code:

Switch view

QDomDocument doc = leXml();
RemoveGroup(&doc,"Google");
qDebug() << doc.toString();

QDomDocument doc = leXml();
RemoveGroup(&doc,"Google");
qDebug() << doc.toString();

To copy to clipboard, switch view to plain text mode

**VitaliBR** · 8th February 2011, 09:51

It appeared in the Debug

start remove: "Google"
not empty... length: 1
processing 0 -> "Google"
removing
"<!DOCTYPE List>
<list>
<client>
<dns>google.com.br</dns>
<phone>+55162223232</phone>
<name>Google</name>
</client>
</list>"

**stampede** · 8th February 2011, 10:38

Ok, now I see what's the problem here.
In order to remove child element 'el' with "doc->removeChild( el )", 'el' should be direct child of the "doc" node. <client> is not direct child of your document, its a child of root element of your document, so this will work:

Qt Code:

Switch view

twmDomDocument->documentElement().removeChild( domTwm.at(i) );

twmDomDocument->documentElement().removeChild( domTwm.at(i) );

To copy to clipboard, switch view to plain text mode

---
I have tested it on this document:

Qt Code:

Switch view

<list>
 <client name="Google">
  <dns>google.com.br</dns>
  <phone>+5521XXXXXXXX</phone>
 </client>
 <client name="Hotmail">
  <dns>hotmail.com</dns>
  <phone>+5535XXXXXXXX</phone>
 </client>
</list>

<list>
 <client name="Google">
  <dns>google.com.br</dns>
  <phone>+5521XXXXXXXX</phone>
 </client>
 <client name="Hotmail">
  <dns>hotmail.com</dns>
  <phone>+5535XXXXXXXX</phone>
 </client>
</list>

To copy to clipboard, switch view to plain text mode

code:

Qt Code:

Switch view

QFile f("test.xml");
	f.open( QIODevice::ReadOnly | QIODevice::Text );
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,"Google");
	qDebug() << doc.toString();

QFile f("test.xml");
	f.open( QIODevice::ReadOnly | QIODevice::Text );
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,"Google");
	qDebug() << doc.toString();

To copy to clipboard, switch view to plain text mode

output:

<list>
<client name="Hotmail" >
<dns>hotmail.com</dns>
<phone>+5535XXXXXXXX</phone>
</client>
</list>

**VitaliBR** · 10th February 2011, 10:57

Ok

Thanks for your help
I need to save this change in the XML? If yes, how I do it?

**stampede** · 10th February 2011, 19:22

I need to save this change in the XML? If yes, how I do it?

The method you have changes QDomDocument object, which not implies change in file from which you get xml string. To save changes, simply overwrite previous content of the xml file using the updated QDomDocument object.

**VitaliBR** · 11th February 2011, 01:17

But why is not Google removing my XML?

the button (action) remover

Qt Code:

Switch view

void Remove::Remover()
{
	QFile f("List.xml");
	f.open( QIODevice::ReadOnly | QIODevice::Text );
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,"Google");
 
	QTextStream out(&f);
	out << doc.toString();
 
	f.close();
 
	QMessageBox::information(0,tr("Warning!"),tr("The Client %1 has been removed!").arg("Google"));
 
}

void Remove::Remover()
{
	QFile f("List.xml");
	f.open( QIODevice::ReadOnly | QIODevice::Text );
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,"Google");

	QTextStream out(&f);
	out << doc.toString();

	f.close();

	QMessageBox::information(0,tr("Warning!"),tr("The Client %1 has been removed!").arg("Google"));

}

To copy to clipboard, switch view to plain text mode

**stampede** · 11th February 2011, 16:25

But why is not Google removing my XML?

What do you mean ? Remove method is not working ? Have you updated it with my previous suggestion ?
Or do you mean that content of file is not updated ? If yes, then well...

Qt Code:

Switch view

f.open( QIODevice::ReadOnly | QIODevice::Text );
//...
QTextStream out(&f);
out << doc.toString();

f.open( QIODevice::ReadOnly | QIODevice::Text );
//...
QTextStream out(&f);
out << doc.toString();

To copy to clipboard, switch view to plain text mode

'f' is still opened in ReadOnly mode when you try to write to it.

**VitaliBR** · 15th February 2011, 11:04

I did so:

Qt Code:

Switch view

void Remove::Remover()
{
	QFile f("List.xml");
	f.open(QIODevice::WriteOnly);
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,"Google");
 
	QTextStream out(&f);
	out << doc.toString();
 
	f.close();
 
	QMessageBox::information(0,tr("Warning!"),tr("The Client %1 has been removed!").arg("Google"));
}

void Remove::Remover()
{
	QFile f("List.xml");
	f.open(QIODevice::WriteOnly);
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,"Google");

	QTextStream out(&f);
	out << doc.toString();

	f.close();

	QMessageBox::information(0,tr("Warning!"),tr("The Client %1 has been removed!").arg("Google"));
}

To copy to clipboard, switch view to plain text mode

Qt Code:

Switch view

void Remove::RemoveGroup(QDomDocument *twmDomDocument, QString theGroupName )
{
	QDomNodeList domTwm = twmDomDocument->elementsByTagName( "client" );
 
	if ( !domTwm.isEmpty() )
	{
		for ( uint i = 0; i < domTwm.length(); i++ )
		{
			if ( domTwm.at(i).toElement().attribute( "name" ) == theGroupName )
			{   
				twmDomDocument->documentElement().removeChild( domTwm.at(i) );
			}
		}
	}
}

void Remove::RemoveGroup(QDomDocument *twmDomDocument, QString theGroupName )
{
	QDomNodeList domTwm = twmDomDocument->elementsByTagName( "client" );

	if ( !domTwm.isEmpty() )
	{
		for ( uint i = 0; i < domTwm.length(); i++ )
		{
			if ( domTwm.at(i).toElement().attribute( "name" ) == theGroupName )
			{   
				twmDomDocument->documentElement().removeChild( domTwm.at(i) );
			}
		}
	}
}

To copy to clipboard, switch view to plain text mode

But instead of it just delete the Google of the XML, it leaves blank XML file (delete everything)

**stampede** · 15th February 2011, 11:50

Qt Code:

Switch view

f.open(QIODevice::WriteOnly);
	QDomDocument doc;
	doc.setContent( &f );

f.open(QIODevice::WriteOnly);
	QDomDocument doc;
	doc.setContent( &f );

To copy to clipboard, switch view to plain text mode

Now you are trying to read from file opened in WriteOnly mode ...
Think, this "problem" is not really difficult. Don't just copy-paste, you're supposed to be a programmer, right ?
In order to give you the next tip I'll need to write the code for you.

**VitaliBR** · 15th February 2011, 13:59

Thanks

now worked

I did so:

Qt Code:

Switch view

QFile f("List.xml");
	f.open(QIODevice::ReadWrite | QIODevice::Text);
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,ui.comboBox->currentText());

QFile f("List.xml");
	f.open(QIODevice::ReadWrite | QIODevice::Text);
	QDomDocument doc;
	doc.setContent( &f );
	RemoveGroup(&doc,ui.comboBox->currentText());

To copy to clipboard, switch view to plain text mode

A single doubt, I researched and tried but could not:
When he saves the new list in XML, it does not erase the old one, ie it saves the new list after the old list

Qt Code:

Switch view

<!DOCTYPE List><list>
 <client>
  <dns>google.com.br</dns>
  <phone>(19)3632-9244</phone>
  <name>Google</name>
 </client>
 <client>
  <dns>uol.com.br</dns>
  <phone>(16)3307-5496</phone>
  <name>Uol</name>
 </client>
 <client>
  <dns>terra.com.br</dns>
  <phone>(21)3368-0422</phone>
  <name>Terra</name>
 </client>
</list>
<!DOCTYPE List><list>
 <client>
  <dns>uol.com.br</dns>
  <phone>(16)3307-5496</phone>
  <name>Uol</name>
 </client>
 <client>
  <dns>terra.com.br</dns>
  <phone>(21)3368-0422</phone>
  <name>Terra</name>
 </client>
</list>

<!DOCTYPE List><list>
 <client>
  <dns>google.com.br</dns>
  <phone>(19)3632-9244</phone>
  <name>Google</name>
 </client>
 <client>
  <dns>uol.com.br</dns>
  <phone>(16)3307-5496</phone>
  <name>Uol</name>
 </client>
 <client>
  <dns>terra.com.br</dns>
  <phone>(21)3368-0422</phone>
  <name>Terra</name>
 </client>
</list>
<!DOCTYPE List><list>
 <client>
  <dns>uol.com.br</dns>
  <phone>(16)3307-5496</phone>
  <name>Uol</name>
 </client>
 <client>
  <dns>terra.com.br</dns>
  <phone>(21)3368-0422</phone>
  <name>Terra</name>
 </client>
</list>

To copy to clipboard, switch view to plain text mode

**VitaliBR** · 16th February 2011, 10:46

I tried using a doc.clear(), but did not work

**stampede** · 16th February 2011, 12:12

Try it this way:
1) open file in ReadOnly mode, create your QDomDocument from it
2) close the file
3) do the processing of xml
4) open the same file again with WriteOnly, and Truncate flags set ( should clear previous content )
5) save new xml to file and close it

**VitaliBR** · 16th February 2011, 13:28

Worked

Thanks guy!!

Thread: Remove element of xml

Thread Tools

Search Thread

Display

Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

The following user says thank you to stampede for this useful post:

Re: Remove element of xml

Re: Remove element of xml

The following user says thank you to stampede for this useful post:

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Re: Remove element of xml

Similar Threads

[QML] Video element

Problem with translate one element

How to get focum element on QWebPage?

Change a QList element

Fix element in risizing window

Bookmarks

Bookmarks

Posting Permissions