QXmlSerializer Class | Qt XML Patterns 5.14.1

Qt 5.14 | Qt XML Patterns | C++ Classes | QXmlSerializer

Qt 5.14.1 Reference Documentation

# QXmlSerializer Class

The QXmlSerializer class is an implementation of QAbstractXmlReceiver for transforming XQuery output into unformatted XML. More...

Header: | #include <QXmlSerializer>
qmake: | QT += xmlpatterns
Since: | Qt 4.4
Inherits: | QAbstractXmlReceiver
Inherited By: | QXmlFormatter

This class was introduced in Qt 4.4.

- List of all members, including inherited members

Note: All functions in this class are reentrant.

## Public Functions

| QXmlSerializer(const QXmlQuery &query, QIODevice *outputDevice)
const QTextCodec * | codec() const
QIODevice * | outputDevice() const
void | setCodec(const QTextCodec *outputCodec)

## Reimplemented Public Functions

virtual void | atomicValue(const QVariant &value) override
virtual void | attribute(const QXmlName &name, const QStringRef &value) override
virtual void | characters(const QStringRef &value) override
virtual void | comment(const QString &value) override
virtual void | endDocument() override
virtual void | endElement() override
virtual void | endOfSequence() override
virtual void | namespaceBinding(const QXmlName &nb) override
virtual void | processingInstruction(const QXmlName &name, const QString &value) override
virtual void | startDocument() override
virtual void | startElement(const QXmlName &name) override
virtual void | startOfSequence() override

## Detailed Description

QXmlSerializer translates an XQuery sequence, usually the output of an QXmlQuery, into XML. Consider the example:

      QXmlQuery query;
      query.setQuery("doc('index.html')/html/body/p[1]");

      QXmlSerializer serializer(query, myOutputDevice);
      query.evaluateTo(&serializer);

First it constructs a query that gets the first paragraph from document `index.html`. Then it constructs an instance of this class with the query and myOutputDevice. Finally, it evaluates the query, producing an ordered sequence of calls to the serializer's callback functions. The sequence of callbacks transforms the query output to XML and writes it to myOutputDevice.

QXmlSerializer will:

- Declare namespaces when needed,
- Use appropriate escaping, when characters can't be represented in the XML,
- Handle line endings appropriately,
- Report errors, when it can't serialize the content, e.g., when asked to serialize an attribute that is a top-level node, or when more than one top-level element is encountered.

If an error occurs during serialization, result is undefined unless the serializer is driven through a call to QXmlQuery::evaluateTo().

If the generated XML should be indented and formatted for reading, use QXmlFormatter.

See also XSLT 2.0 and XQuery 1.0 Serialization and QXmlFormatter.

## Member Function Documentation

### QXmlSerializer::QXmlSerializer(const QXmlQuery &query, QIODevice *outputDevice)

Constructs a serializer that uses the name pool and message handler in query, and writes the output to outputDevice.

outputDevice must be a valid, non-null device that is open in write mode, otherwise behavior is undefined.

outputDevice must not be opened with QIODevice::Text because it will cause the output to be incorrect. This class will ensure line endings are serialized as according with the XML specification. QXmlSerializer does not take ownership of outputDevice.

### `[override virtual]` void QXmlSerializer::atomicValue(const QVariant &value)

Reimplements: QAbstractXmlReceiver::atomicValue(const QVariant &value).

### `[override virtual]` void QXmlSerializer::attribute(const QXmlName &name, const QStringRef &value)

Reimplements: QAbstractXmlReceiver::attribute(const QXmlName &name, const QStringRef &value).

### `[override virtual]` void QXmlSerializer::characters(const QStringRef &value)

Reimplements: QAbstractXmlReceiver::characters(const QStringRef &value).

### const QTextCodec *QXmlSerializer::codec() const

Returns the codec being used by the serializer for encoding its XML output.

See also setCodec().

### `[override virtual]` void QXmlSerializer::comment(const QString &value)

Reimplements: QAbstractXmlReceiver::comment(const QString &value).

### `[override virtual]` void QXmlSerializer::endDocument()

Reimplements: QAbstractXmlReceiver::endDocument().

### `[override virtual]` void QXmlSerializer::endElement()

Reimplements: QAbstractXmlReceiver::endElement().

### `[override virtual]` void QXmlSerializer::endOfSequence()

Reimplements: QAbstractXmlReceiver::endOfSequence().

### `[override virtual]` void QXmlSerializer::namespaceBinding(const QXmlName &nb)

Reimplements: QAbstractXmlReceiver::namespaceBinding(const QXmlName &name).

### QIODevice *QXmlSerializer::outputDevice() const

Returns a pointer to the output device. There is no corresponding function to set the output device, because the output device must be passed to the constructor. The serializer does not take ownership of its IO device.

### `[override virtual]` void QXmlSerializer::processingInstruction(const QXmlName &name, const QString &value)

Reimplements: QAbstractXmlReceiver::processingInstruction(const QXmlName &target, const QString &value).

### void QXmlSerializer::setCodec(const QTextCodec *outputCodec)

Sets the codec the serializer will use for encoding its XML output. The output codec is set to outputCodec. By default, the output codec is set to the one for `UTF-8`. The serializer does not take ownership of the codec.

See also codec().

### `[override virtual]` void QXmlSerializer::startDocument()

Reimplements: QAbstractXmlReceiver::startDocument().

### `[override virtual]` void QXmlSerializer::startElement(const QXmlName &name)

Reimplements: QAbstractXmlReceiver::startElement(const QXmlName &name).

### `[override virtual]` void QXmlSerializer::startOfSequence()

Reimplements: QAbstractXmlReceiver::startOfSequence().