- Qt 5.15
- Qt XML
- C++ Classes
- QXmlReader
- Qt 5.15.19 Reference Documentation

# QXmlReader Class

The QXmlReader class provides an interface for XML readers (i.e. parsers). More...

Header: | #include <QXmlReader>
qmake: | QT += xml
Inherited By: | QXmlSimpleReader

This class is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code.

- List of all members, including inherited members
- Obsolete members

Note: All functions in this class are reentrant.

## Public Functions

virtual | ~QXmlReader()
virtual QXmlDTDHandler * | DTDHandler() const = 0
virtual QXmlContentHandler * | contentHandler() const = 0
virtual QXmlDeclHandler * | declHandler() const = 0
virtual QXmlEntityResolver * | entityResolver() const = 0
virtual QXmlErrorHandler * | errorHandler() const = 0
virtual bool | feature(const QString &name, bool *ok = nullptr) const = 0
virtual bool | hasFeature(const QString &name) const = 0
virtual bool | hasProperty(const QString &name) const = 0
virtual QXmlLexicalHandler * | lexicalHandler() const = 0
virtual bool | parse(const QXmlInputSource *input) = 0
virtual void * | property(const QString &name, bool *ok = nullptr) const = 0
virtual void | setContentHandler(QXmlContentHandler *handler) = 0
virtual void | setDTDHandler(QXmlDTDHandler *handler) = 0
virtual void | setDeclHandler(QXmlDeclHandler *handler) = 0
virtual void | setEntityResolver(QXmlEntityResolver *handler) = 0
virtual void | setErrorHandler(QXmlErrorHandler *handler) = 0
virtual void | setFeature(const QString &name, bool value) = 0
virtual void | setLexicalHandler(QXmlLexicalHandler *handler) = 0
virtual void | setProperty(const QString &name, void *value) = 0

## Detailed Description

This abstract class provides an interface for all of Qt's XML readers. Currently there is only one implementation of a reader included in Qt's XML module: QXmlSimpleReader. In future releases there might be more readers with different properties available (e.g. a validating parser).

The design of the XML classes follows the SAX2 Java interface, with the names adapted to fit Qt naming conventions. It should be very easy for anybody who has worked with SAX2 to get started with the Qt XML classes.

All readers use the class QXmlInputSource to read the input document. Since you are normally interested in particular content in the XML document, the reader reports the content through special handler classes (QXmlDTDHandler, QXmlDeclHandler, QXmlContentHandler, QXmlEntityResolver, QXmlErrorHandler and QXmlLexicalHandler), which you must subclass, if you want to process the contents.

Since the handler classes only describe interfaces you must implement all the functions. We provide the QXmlDefaultHandler class to make this easier: it implements a default behavior (do nothing) for all functions, so you can subclass it and just implement the functions you are interested in.

Features and properties of the reader can be set with setFeature() and setProperty() respectively. You can set the reader to use your own subclasses with setEntityResolver(), setDTDHandler(), setContentHandler(), setErrorHandler(), setLexicalHandler() and setDeclHandler(). The parse itself is started with a call to parse().

Note that this class is now deprecated, please use QXmlStreamReader or QDomDocument for reading XML files.

See also QXmlSimpleReader.

## Member Function Documentation

### `[virtual]` QXmlReader::~QXmlReader()

Destroys the reader.

### `[pure virtual]` QXmlDTDHandler *QXmlReader::DTDHandler() const

Returns the DTD handler or `nullptr` if none was set.

See also setDTDHandler().

### `[pure virtual]` QXmlContentHandler *QXmlReader::contentHandler() const

Returns the content handler or `nullptr` if none was set.

See also setContentHandler().

### `[pure virtual]` QXmlDeclHandler *QXmlReader::declHandler() const

Returns the declaration handler or `nullptr` if none was set.

See also setDeclHandler().

### `[pure virtual]` QXmlEntityResolver *QXmlReader::entityResolver() const

Returns the entity resolver or `nullptr` if none was set.

See also setEntityResolver().

### `[pure virtual]` QXmlErrorHandler *QXmlReader::errorHandler() const

Returns the error handler or `nullptr` if none is set.

See also setErrorHandler().

### `[pure virtual]` bool QXmlReader::feature(const QString &name, bool *ok = nullptr) const

If the reader has the feature called name, the feature's value is returned. If no such feature exists the return value is undefined.

If ok is not `nullptr`: `*`ok is set to true if the reader has the feature called name; otherwise `*`ok is set to false.

See also setFeature() and hasFeature().

### `[pure virtual]` bool QXmlReader::hasFeature(const QString &name) const

Returns `true` if the reader has the feature called name; otherwise returns `false`.

See also feature() and setFeature().

### `[pure virtual]` bool QXmlReader::hasProperty(const QString &name) const

Returns `true` if the reader has the property name; otherwise returns `false`.

See also property() and setProperty().

### `[pure virtual]` QXmlLexicalHandler *QXmlReader::lexicalHandler() const

Returns the lexical handler or `nullptr` if none was set.

See also setLexicalHandler().

### `[pure virtual]` bool QXmlReader::parse(const QXmlInputSource *input)

Reads an XML document from input and parses it. Returns `true` if the parsing was successful; otherwise returns `false`.

### `[pure virtual]` void *QXmlReader::property(const QString &name, bool *ok = nullptr) const

If the reader has the property name, this function returns the value of the property; otherwise the return value is undefined.

If ok is not `nullptr`: if the reader has the name property `*`ok is set to true; otherwise `*`ok is set to false.

See also setProperty() and hasProperty().

### `[pure virtual]` void QXmlReader::setContentHandler(QXmlContentHandler *handler)

Sets the content handler to handler.

See also contentHandler().

### `[pure virtual]` void QXmlReader::setDTDHandler(QXmlDTDHandler *handler)

Sets the DTD handler to handler.

See also DTDHandler().

### `[pure virtual]` void QXmlReader::setDeclHandler(QXmlDeclHandler *handler)

Sets the declaration handler to handler.

See also declHandler().

### `[pure virtual]` void QXmlReader::setEntityResolver(QXmlEntityResolver *handler)

Sets the entity resolver to handler.

See also entityResolver().

### `[pure virtual]` void QXmlReader::setErrorHandler(QXmlErrorHandler *handler)

Sets the error handler to handler. Clears the error handler if handler is 0.

See also errorHandler().

### `[pure virtual]` void QXmlReader::setFeature(const QString &name, bool value)

Sets the feature called name to the given value. If the reader doesn't have the feature nothing happens.

See also feature() and hasFeature().

### `[pure virtual]` void QXmlReader::setLexicalHandler(QXmlLexicalHandler *handler)

Sets the lexical handler to handler.

See also lexicalHandler().

### `[pure virtual]` void QXmlReader::setProperty(const QString &name, void *value)

Sets the property name to value. If the reader doesn't have the property nothing happens.

See also property() and hasProperty().