CopperSpice API  1.7.2
QXmlStreamWriter Class Reference

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
 
QTextCodeccodec () const
 
QIODevicedevice () 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 snippet 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.

See also
autoFormatting

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

The auto-formatting flag of the stream writer.

This property 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. The indentation depth can be controlled through the autoFormattingIndent property.

By default, auto-formatting is disabled.

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.

See also
autoFormatting
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 0 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 "&lt;", "&amp;", and "&quot;". To avoid the forbidden sequence "]]>" the > is also escaped to "&gt;".

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 "-". Note that 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 function 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.

Note that 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, 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.

Note that 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.

This is a convenience function equivalent to:

writeStartElement(namespaceUri, name);
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.