Qt 4.7: QXmlItem Class Reference

Qt Reference Documentation

# QXmlItem Class Reference

The QXmlItem class contains either an XML node or an atomic value. More...

     #include <QXmlItem>

Note: All functions in this class are reentrant.

This class was introduced in Qt 4.4.

- List of all members, including inherited members

## Public Types

typedef | Iterator

## Public Functions

| QXmlItem ()
| QXmlItem ( const QXmlItem & other )
| QXmlItem ( const QXmlNodeModelIndex & node )
| QXmlItem ( const QVariant & atomicValue )
| ~QXmlItem ()
bool | isAtomicValue () const
bool | isNode () const
bool | isNull () const
QVariant | toAtomicValue () const
QXmlNodeModelIndex | toNodeModelIndex () const
QXmlItem & | operator= ( const QXmlItem & other )

## Detailed Description

The QXmlItem class contains either an XML node or an atomic value.

In XQuery, all expressions evaluate to a sequence of items, where each item is either an XML node or an atomic value. The query in the following snippet evaluates to sequence of five items.

     <aNode/>,
     xs:base64Binary("FFFF"),
     current-date(),
     3e3, (: A floating point value :)
     attribute {"name"} {()}

The five items are: An element, an atomic value (binary data encoded in base64), a date, a float, and an attribute.

QXmlItem is the class that represents these XQuery items in the QtXmlPatterns API. A non-null instance of QXmlItem is either a node or an atomic value. Calling isNode() or isAtomicValue() tells you which it is. Atomic values are represented elsewhere in the Qt API as instances of QVariant, and an instance of QXmlItem that represents an atomic value can be converted to a QVariant by calling toAtomicValue(). A QXmlItem that wraps a node is represented elsewhere as an instance of QXmlNodeModelIndex. A node QXmlItem can be converted to a QXmlNodeModelIndex by calling toNodeModelIndex().

A default constructed QXmlItem instance is neither a node nor an atomic value. It is considered null, in which case isNull() returns true.

An instance of QXmlItem will be left dangling if the XML node model it refers to is deleted, if it is a QXmlNodeModelIndex.

## Member Type Documentation

### typedef QXmlItem::Iterator

A QAbstractXmlForwardIterator over QXmlItem.

## Member Function Documentation

### QXmlItem::QXmlItem ()

Constructs a null QXmlItem that is neither a node nor an atomic value. isNull() returns true for a default constructed instance.

### QXmlItem::QXmlItem ( const QXmlItem & other )

The copy constructor constructs a copy of other.

### QXmlItem::QXmlItem ( const QXmlNodeModelIndex & node )

Constructs a node QXmlItem that is a copy of node.

See also isNode().

### QXmlItem::QXmlItem ( const QVariant & atomicValue )

Constructs an atomic value QXmlItem with atomicValue.

See also isAtomicValue().

### QXmlItem::~QXmlItem ()

Destructor.

### bool QXmlItem::isAtomicValue () const

Returns true if this item is an atomic value. Returns false if it is a node or null.

See also isNull() and isNode().

### bool QXmlItem::isNode () const

Returns true if this item is a Node. Returns false if it is an atomic value or null.

See also isNull() and isAtomicValue().

### bool QXmlItem::isNull () const

Returns true if this QXmlItem is neither a node nor an atomic value. Default constructed instances of QXmlItem are null.

### QVariant QXmlItem::toAtomicValue () const

If this QXmlItem represents an atomic value, it is converted to an appropriate QVariant and returned. If this QXmlItem is not an atomic value, the return value is a default constructed QVariant. You can call isAtomicValue() to test whether the item is an atomic value.

See also isAtomicValue().

### QXmlNodeModelIndex QXmlItem::toNodeModelIndex () const

If this QXmlItem represents a node, it returns the item as a QXmlNodeModelIndex. If this QXmlItem is not a node, the return value is undefined. You can call isNode() to test whether the item is a node.

See also isNode().

### QXmlItem & QXmlItem::operator= ( const QXmlItem & other )

Assigns other to `this`.