The QXmlStreamWriter class provides an XML writer with a simple streaming API. More...

Public Methods
	QXmlStreamWriter ()

	QXmlStreamWriter (QByteArray *array)

	QXmlStreamWriter (QIODevice *device)

	QXmlStreamWriter (QString *string)

	~QXmlStreamWriter ()

bool	autoFormatting () const

int	autoFormattingIndent () const

QTextCodec *	codec () const

QIODevice *	device () const

bool	hasError () const

void	setAutoFormatting (bool enable)

void	setAutoFormattingIndent (int spacesOrTabs)

void	setCodec (const char *codecName)

void	setCodec (QTextCodec *codec)

void	setDevice (QIODevice *device)

void	writeAttribute (const QString &namespaceUri, const QString &name, const QString &value)

void	writeAttribute (const QString &qualifiedName, const QString &value)

void	writeAttribute (const QXmlStreamAttribute &attribute)

void	writeAttributes (const QXmlStreamAttributes &attributes)

void	writeCDATA (const QString &text)

void	writeCharacters (const QString &text)

void	writeComment (const QString &text)

void	writeCurrentToken (const QXmlStreamReader &reader)

void	writeDefaultNamespace (const QString &namespaceUri)

void	writeDTD (const QString &dtd)

void	writeEmptyElement (const QString &namespaceUri, const QString &name)

void	writeEmptyElement (const QString &qualifiedName)

void	writeEndDocument ()

void	writeEndElement ()

void	writeEntityReference (const QString &name)

void	writeNamespace (const QString &namespaceUri, const QString &prefix=QString ())

void	writeProcessingInstruction (const QString &target, const QString &data=QString ())

void	writeStartDocument ()

void	writeStartDocument (const QString &version)

void	writeStartDocument (const QString &version, bool standalone)

void	writeStartElement (const QString &namespaceUri, const QString &name)

void	writeStartElement (const QString &qualifiedName)

void	writeTextElement (const QString &namespaceUri, const QString &name, const QString &text)

void	writeTextElement (const QString &qualifiedName, const QString &text)

Detailed Description

The QXmlStreamWriter class provides an XML writer with a simple streaming API. QXmlStreamWriter is the counterpart to QXmlStreamReader for writing XML. Like its related class, it operates on a QIODevice specified with setDevice(). The API is simple and straightforward: for every XML token or event you want to write, the writer provides a specialized function.

You start a document with writeStartDocument() and end it with writeEndDocument(). This will implicitly close all remaining open tags. Element tags are opened with writeStartElement() followed by writeAttribute() or writeAttributes(), element content, and then writeEndElement(). A shorter form writeEmptyElement() can be used to write empty elements, followed by writeAttributes().

Element content consists of either characters, entity references or nested elements. It is written with writeCharacters(), which also takes care of escaping all forbidden characters and character sequences, writeEntityReference(), or subsequent calls to writeStartElement(). A convenience method writeTextElement() can be used for writing terminal elements that contain nothing but text.

The following abridged code shows the basic use of the class to write formatted XML with indentation.

QXmlStreamWriter stream(&output);
stream.setAutoFormatting(true);
stream.writeStartDocument();
 
stream.writeStartElement("bookmark");
stream.writeAttribute("href", "https://www.copperspice.com/");
stream.writeTextElement("title", "CopperSpice Home");
stream.writeEndElement();                                        // bookmark
 
stream.writeEndDocument();

QXmlStreamWriter takes care of prefixing namespaces, all you have to do is specify the namespaceUri when writing elements or attributes. If you must conform to certain prefixes, you can force the writer to use them by declaring the namespaces manually with either writeNamespace() or writeDefaultNamespace(). Alternatively, you can bypass the stream writer's namespace support and use overloaded methods that take a qualified name instead. The namespace http://www.w3.org/XML/1998/namespace is implicit and mapped to the prefix xml.

The stream writer can automatically format the generated XML data by adding line-breaks and indentation to empty sections between elements, making the XML data more readable for humans and easier to work with for most source code management systems. The feature can be turned on with the autoFormatting property, and customized with the autoFormattingIndent property.

Other functions are writeCDATA(), writeComment(), writeProcessingInstruction(), and writeDTD(). Chaining of XML streams is supported with writeCurrentToken().

By default, QXmlStreamWriter encodes XML in UTF-8. Different encodings can be enforced using setCodec().

If an error occurs while writing to the underlying device, hasError() starts returning true and subsequent writes are ignored.

Auto Formatting

This class contains a flag which controls whether or not the stream writer automatically formats the generated XML data. If enabled, the writer automatically adds line-breaks and indentation to empty sections between elements (ignorable whitespace). The main purpose of auto-formatting is to split the data into several lines, and to increase readability for a human reader.

By default auto-formatting is disabled.

Auto Formatting Indent

This class contains a flag which holds the number of spaces or tabs used for indentation when auto-formatting is enabled. Positive numbers indicate spaces and negative numbers indicate tabs. The default indentation is 4.

The methods autoFormattingIndent() and setAutoFormattingIndent() are used to read and write to this flag.

Constructor & Destructor Documentation

QXmlStreamWriter::QXmlStreamWriter ( )

Constructs a stream writer.

See also: setDevice()

QXmlStreamWriter::QXmlStreamWriter ( QIODevice * device )

Constructs a stream writer that writes into device;

QXmlStreamWriter::QXmlStreamWriter ( QByteArray * array )

Constructs a stream writer that writes into array. This is the same as creating an xml writer that operates on a QBuffer device which in turn operates on array.

QXmlStreamWriter::QXmlStreamWriter ( QString * string )

Constructs a stream writer that writes into string.

QXmlStreamWriter::~QXmlStreamWriter ( )

Destroys the current QXmlStreamWriter object.

Method Documentation

bool QXmlStreamWriter::autoFormatting ( ) const

Reurns the current state of the auto-formatting flag of the stream writer.

int QXmlStreamWriter::autoFormattingIndent ( ) const

This property holds the number of spaces or tabs used for indentation when auto-formatting is enabled. Positive numbers indicate spaces, negative numbers tabs.

QTextCodec * QXmlStreamWriter::codec ( ) const

Returns the codec that is currently assigned to the stream.

See also: setCodec()

QIODevice * QXmlStreamWriter::device ( ) const

Returns the current device associated with the QXmlStreamWriter or a nullptr if no device has been assigned.

See also: setDevice()

bool QXmlStreamWriter::hasError ( ) const

Returns true if the stream failed to write to the underlying device, otherwise returns false.

The error status is never reset. Writes happening after the error occurred are ignored, even if the error condition is cleared.

void QXmlStreamWriter::setAutoFormatting ( bool enable )

Enables auto formatting if enable is true, otherwise disables auto formatting.

void QXmlStreamWriter::setAutoFormattingIndent ( int spacesOrTabs )

Sets the value of the property setAutoFormattingIndent to spacesOrTabs.

void QXmlStreamWriter::setCodec ( const char * codecName )

Sets the codec for this stream to the QTextCodec for the encoding specified by codecName. Common values for codecName include "ISO 8859-1", "UTF-8", and "UTF-16". If the encoding is not recognized, nothing happens.

See also: QTextCodec::codecForName()

void QXmlStreamWriter::setCodec ( QTextCodec * codec )

Sets the codec for this stream to codec. The codec is used for encoding any data that is written. By default, QXmlStreamWriter uses UTF-8.

The encoding information is stored in the initial xml tag which gets written when you call writeStartDocument(). Call this function before calling writeStartDocument().

See also: codec()

void QXmlStreamWriter::setDevice ( QIODevice * device )

Sets the current device to device. If you want the stream to write into a QByteArray, you can create a QBuffer device.

See also: device()

void QXmlStreamWriter::writeAttribute	(	const QString &	namespaceUri,
		const QString &	name,
		const QString &	value
	)

Writes an attribute with name and value, prefixed for the specified namespaceUri. If the namespace has not been declared yet, QXmlStreamWriter will generate a namespace declaration for it.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement().

void QXmlStreamWriter::writeAttribute	(	const QString &	qualifiedName,
		const QString &	value
	)

Writes an attribute with qualifiedName and value.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement().

void QXmlStreamWriter::writeAttribute ( const QXmlStreamAttribute & attribute )

Writes the attribute. This method can only be called after writeStartElement() before any content is written, or after writeEmptyElement().

void QXmlStreamWriter::writeAttributes ( const QXmlStreamAttributes & attributes )

Writes the attribute vector attributes. If a namespace referenced in an attribute not been declared yet, QXmlStreamWriter will generate a namespace declaration for it.

This function can only be called after writeStartElement() before any content is written, or after writeEmptyElement().

See also: writeAttribute(), writeNamespace()

void QXmlStreamWriter::writeCDATA ( const QString & text )

Writes text as CDATA section. If text contains the forbidden character sequence "]]>", it is split into different CDATA sections.

This function mainly exists for completeness. Normally you should not need use it, because writeCharacters() automatically escapes all non-content characters.

void QXmlStreamWriter::writeCharacters ( const QString & text )

Writes text. The characters <, & and " are escaped as entity references "<", "&", and """. To avoid the forbidden sequence "]]>" the > is also escaped to ">".

See also: writeEntityReference()

void QXmlStreamWriter::writeComment ( const QString & text )

Writes text as XML comment, where text must not contain the forbidden sequence "–" or end with "-". XML does not provide any way to escape "-" in a comment.

void QXmlStreamWriter::writeCurrentToken ( const QXmlStreamReader & reader )

Writes the current state of the reader. All possible valid states are supported. The purpose of this method is to support chained processing of XML data.

See also: QXmlStreamReader::tokenType()

void QXmlStreamWriter::writeDefaultNamespace ( const QString & namespaceUri )

Writes a default namespace declaration for namespaceUri. If writeStartElement() or writeEmptyElement() was called, the declaration applies to the current element, otherwise it applies to the next child element.

The namespaces http://www.w3.org/XML/1998/namespace (bound to xmlns) and http://www.w3.org/2000/xmlns/ (bound to xml) by definition can not be declared as default.

void QXmlStreamWriter::writeDTD ( const QString & dtd )

Writes a DTD section. The dtd represents the entire doctypedecl production from the XML 1.0 specification.

void QXmlStreamWriter::writeEmptyElement	(	const QString &	namespaceUri,
		const QString &	name
	)

Writes an empty element with name, prefixed for the specified namespaceUri. If the namespace has not been declared, QXmlStreamWriter will generate a namespace declaration for it. Subsequent calls to writeAttribute() will add attributes to this element.

See also: writeNamespace()

void QXmlStreamWriter::writeEmptyElement ( const QString & qualifiedName )

Writes an empty element with qualified name qualifiedName. Subsequent calls to writeAttribute() will add attributes to this element.

void QXmlStreamWriter::writeEndDocument ( )

Closes all remaining open start elements and writes a newline.

See also: writeStartDocument()

void QXmlStreamWriter::writeEndElement ( )

Closes the previous start element.

See also: writeStartElement()

void QXmlStreamWriter::writeEntityReference ( const QString & name )

Writes the entity reference name to the stream, as "&name;".

void QXmlStreamWriter::writeNamespace	(	const QString &	namespaceUri,
		const QString &	prefix = `QString()`
	)

Writes a namespace declaration for namespaceUri with prefix. If prefix is empty then QXmlStreamWriter assigns a unique prefix consisting of the letter 'n' followed by a number.

If writeStartElement() or writeEmptyElement() was called, the declaration applies to the current element, otherwise it applies to the next child element.

The prefix xml is both predefined and reserved for http://www.w3.org/XML/1998/namespace, which in turn can not be bound to any other prefix. The prefix xmlns and its URI http://www.w3.org/2000/xmlns/ are used for the namespace mechanism itself and thus completely forbidden in declarations.

void QXmlStreamWriter::writeProcessingInstruction	(	const QString &	target,
		const QString &	data = `QString()`
	)

Writes an XML processing instruction with target and data, where data must not contain the sequence "?>".

void QXmlStreamWriter::writeStartDocument ( )

Writes a document start with XML version number "1.0". This also writes the encoding information.

See also: writeEndDocument(), setCodec()

void QXmlStreamWriter::writeStartDocument ( const QString & version )

Writes a document start with the XML version number version.

See also: writeEndDocument()

void QXmlStreamWriter::writeStartDocument	(	const QString &	version,
		bool	standalone
	)

Writes a document start with the XML version number version and a standalone attribute standalone.

See also: writeEndDocument()

void QXmlStreamWriter::writeStartElement	(	const QString &	namespaceUri,
		const QString &	name
	)

Writes a start element with name, prefixed for the specified namespaceUri. If the namespace has not been declared yet, QXmlStreamWriter will generate a namespace declaration for it. Subsequent calls to writeAttribute() will add attributes to this element.

See also: writeNamespace(), writeEndElement(), writeEmptyElement()

void QXmlStreamWriter::writeStartElement ( const QString & qualifiedName )

Writes a start element with qualifiedName. Subsequent calls to writeAttribute() will add attributes to this element.

See also: writeEndElement(), writeEmptyElement()

void QXmlStreamWriter::writeTextElement	(	const QString &	namespaceUri,
		const QString &	name,
		const QString &	text
	)

Writes a text element with name, prefixed for the specified namespaceUri, and text. If the namespace has not been declared, QXmlStreamWriter will generate a namespace declaration for it.

Equivalent to calling the following code.

writeStartElement(namespaceUri, name);
writeCharacters(text);
writeEndElement();

void QXmlStreamWriter::writeTextElement	(	const QString &	qualifiedName,
		const QString &	text
	)

Writes a text element with qualifiedName and text.

This method is equivalent to the following code.

writeStartElement(qualifiedName);
writeCharacters(text);
writeEndElement();

Public Methods

Detailed Description

Auto Formatting

Auto Formatting Indent

Constructor & Destructor Documentation

Method Documentation