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QDomNode Class Reference
[XML module]

The QDomNode class is the base class for all the nodes in a DOM tree. More...

#include <qdom.h>

Inherited by QDomDocumentType, QDomDocument, QDomDocumentFragment, QDomCharacterData, QDomAttr, QDomElement, QDomNotation, QDomEntity, QDomEntityReference, and QDomProcessingInstruction.

List of all member functions.

Public Members

Related Functions

Detailed Description

The QDomNode class is the base class for all the nodes in a DOM tree.

Many functions in the DOM return a QDomNode.

You can find out the type of a node using isAttr(), isCDATASection(), isDocumentFragment(), isDocument(), isDocumentType(), isElement(), isEntityReference(), isText(), isEntity(), isNotation(), isProcessingInstruction(), isCharacterData() and isComment().

A QDomNode can be converted into one of its subclasses using toAttr(), toCDATASection(), toDocumentFragment(), toDocument(), toDocumentType(), toElement(), toEntityReference(), toText(), toEntity(), toNotation(), toProcessingInstruction(), toCharacterData() or toComment(). You can convert a node to a null node with clear().

Copies of the QDomNode class share their data using explicit sharing. This means that modifying one node will change all copies. This is especially useful in combination with functions which return a QDomNode, e.g. firstChild(). You can make an independent (deep) copy of the node with cloneNode().

Nodes are inserted with insertBefore(), insertAfter() or appendChild(). You can replace one node with another using replaceChild() and remove a node with removeChild().

To traverse nodes use firstChild() to get a node's first child (if any), and nextSibling() to traverse. QDomNode also provides lastChild(), previousSibling() and parentNode(). To find the first child node with a particular node name use namedItem().

To find out if a node has children use hasChildNodes() and to get a list of all of a node's children use childNodes().

The node's name and value (the meaning of which varies depending on its type) is returned by nodeName() and nodeValue() respectively. The node's type is returned by nodeType(). The node's value can be set with setNodeValue().

The document to which the node belongs is returned by ownerDocument().

Adjacent QDomText nodes can be merged into a single node with normalize().

QDomElement nodes have attributes which can be retrieved with attributes().

QDomElement and QDomAttr nodes can have namespaces which can be retrieved with namespaceURI(). Their local name is retrieved with localName(), and their prefix with prefix(). The prefix can be set with setPrefix().

You can write the XML representation of the node to a text stream with save().

The following example looks for the first element in an XML document and prints the names of all the elements that are its direct children. 

    QDomDocument d;
    d.setContent( someXML );
    QDomNode n = d.firstChild();
    while ( !n.isNull() ) {
        if ( n.isElement() ) {
            QDomElement e = n.toElement();
            cout << "Element name: " << e.tagName() << endl;
            break;
        }
        n = n.nextSibling();
    }

For further information about the Document Object Model see http://www.w3.org/TR/REC-DOM-Level-1/ and http://www.w3.org/TR/DOM-Level-2-Core/. For a more general introduction of the DOM implementation see the QDomDocument documentation.

See also XML.

Member Type Documentation

QDomNode::NodeType

This enum defines the type of the node:

Member Function Documentation

QDomNode::QDomNode ()

Constructs a null node.

QDomNode::QDomNode ( const QDomNode & n )

Constructs a copy of n.

The data of the copy is shared (shallow copy): modifying one node will also change the other. If you want to make a deep copy, use cloneNode().

QDomNode::~QDomNode () [virtual]

Destroys the object and frees its resources.

QDomNode QDomNode::appendChild ( const QDomNode & newChild ) [virtual]

Appends newChild as the node's last child.

If newChild is the child of another node, it is reparented to this node. If newChild is a child of this node, then its position in the list of children is changed.

If newChild is a QDomDocumentFragment, then the children of the fragment are removed from the fragment and appended.

Returns a new reference to newChild.

See also insertBefore(), insertAfter(), replaceChild(), and removeChild().

QDomNamedNodeMap QDomNode::attributes () const [virtual]

Returns a named node map of all attributes. Attributes are only provided for QDomElements.

Changing the attributes in the map will also change the attributes of this QDomNode.

Reimplemented in QDomElement.

QDomNodeList QDomNode::childNodes () const [virtual]

Returns a list of all direct child nodes.

Most often you will call this function on a QDomElement object.

For example, if the XML document looks like this: 

    <body>
    <h1>Heading</h1>
    <p>Hello <b>you</b></p>
    </body>
Then the list of child nodes for the "body"-element will contain the node created by the <h1> tag and the node created by the <p> tag.

The nodes in the list are not copied; so changing the nodes in the list will also change the children of this node.

See also firstChild() and lastChild().

void QDomNode::clear ()

Converts the node into a null node; if it was not a null node before, its type and contents are deleted.

See also isNull().

QDomNode QDomNode::cloneNode ( bool deep = TRUE ) const [virtual]

Creates a deep (not shallow) copy of the QDomNode.

If deep is TRUE, then the cloning is done recursively which means that all the node's children are deep copied too. If deep is FALSE only the node itself is copied and the copy will have no child nodes.

QDomNode QDomNode::firstChild () const [virtual]

Returns the first child of the node. If there is no child node, a null node is returned. Changing the returned node will also change the node in the document tree.

See also lastChild() and childNodes().

Example: xml/outliner/outlinetree.cpp.

bool QDomNode::hasAttributes () const [virtual]

Returns TRUE if the node has attributes; otherwise returns FALSE.

See also attributes().

bool QDomNode::hasChildNodes () const [virtual]

Returns TRUE if the node has one or more children; otherwise returns FALSE.

QDomNode QDomNode::insertAfter ( const QDomNode & newChild, const QDomNode & refChild ) [virtual]

Inserts the node newChild after the child node refChild. refChild must be a direct child of this node. If refChild is null then newChild is appended as this node's last child.

If newChild is the child of another node, it is reparented to this node. If newChild is a child of this node, then its position in the list of children is changed.

If newChild is a QDomDocumentFragment, then the children of the fragment are removed from the fragment and inserted after refChild.

Returns a new reference to newChild on success or a null node on failure.

See also insertBefore(), replaceChild(), removeChild(), and appendChild().

QDomNode QDomNode::insertBefore ( const QDomNode & newChild, const QDomNode & refChild ) [virtual]

Inserts the node newChild before the child node refChild. refChild must be a direct child of this node. If refChild is null then newChild is inserted as the node's first child.

If newChild is the child of another node, it is reparented to this node. If newChild is a child of this node, then its position in the list of children is changed.

If newChild is a QDomDocumentFragment, then the children of the fragment are removed from the fragment and inserted before refChild.

Returns a new reference to newChild on success or a null node on failure.

See also insertAfter(), replaceChild(), removeChild(), and appendChild().

bool QDomNode::isAttr () const [virtual]

Returns TRUE if the node is an attribute; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomAttribute; you can get the QDomAttribute with toAttribute().

See also toAttr().

Reimplemented in QDomAttr.

bool QDomNode::isCDATASection () const [virtual]

Returns TRUE if the node is a CDATA section; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomCDATASection; you can get the QDomCDATASection with toCDATASection().

See also toCDATASection().

Reimplemented in QDomCDATASection.

bool QDomNode::isCharacterData () const [virtual]

Returns TRUE if the node is a character data node; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomCharacterData; you can get the QDomCharacterData with toCharacterData().

See also toCharacterData().

Reimplemented in QDomCharacterData.

bool QDomNode::isComment () const [virtual]

Returns TRUE if the node is a comment; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomComment; you can get the QDomComment with toComment().

See also toComment().

Reimplemented in QDomComment.

bool QDomNode::isDocument () const [virtual]

Returns TRUE if the node is a document; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomDocument; you can get the QDomDocument with toDocument().

See also toDocument().

Reimplemented in QDomDocument.

bool QDomNode::isDocumentFragment () const [virtual]

Returns TRUE if the node is a document fragment; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomDocumentFragment; you can get the QDomDocumentFragment with toDocumentFragment().

See also toDocumentFragment().

Reimplemented in QDomDocumentFragment.

bool QDomNode::isDocumentType () const [virtual]

Returns TRUE if the node is a document type; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomDocumentType; you can get the QDomDocumentType with toDocumentType().

See also toDocumentType().

Reimplemented in QDomDocumentType.

bool QDomNode::isElement () const [virtual]

Returns TRUE if the node is an element; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomElement; you can get the QDomElement with toElement().

See also toElement().

Example: xml/outliner/outlinetree.cpp.

Reimplemented in QDomElement.

bool QDomNode::isEntity () const [virtual]

Returns TRUE if the node is an entity; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomEntity; you can get the QDomEntity with toEntity().

See also toEntity().

Reimplemented in QDomEntity.

bool QDomNode::isEntityReference () const [virtual]

Returns TRUE if the node is an entity reference; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomEntityReference; you can get the QDomEntityReference with toEntityReference().

See also toEntityReference().

Reimplemented in QDomEntityReference.

bool QDomNode::isNotation () const [virtual]

Returns TRUE if the node is a notation; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomNotation; you can get the QDomNotation with toNotation().

See also toNotation().

Reimplemented in QDomNotation.

bool QDomNode::isNull () const

Returns TRUE if this node is null (i.e. if it has no type or contents); otherwise returns FALSE.

Example: xml/outliner/outlinetree.cpp.

bool QDomNode::isProcessingInstruction () const [virtual]

Returns TRUE if the node is a processing instruction; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomProcessingInstruction; you can get the QProcessingInstruction with toProcessingInstruction().

See also toProcessingInstruction().

Reimplemented in QDomProcessingInstruction.

bool QDomNode::isSupported ( const QString & feature, const QString & version ) const [virtual]

Returns TRUE if the DOM implementation implements the feature feature and this feature is supported by this node in the version version; otherwise returns FALSE.

See also QDomImplementation::hasFeature().

bool QDomNode::isText () const [virtual]

Returns TRUE if the node is a text node; otherwise returns FALSE.

If this function returns TRUE, it does not imply that this object is a QDomText; you can get the QDomText with toText().

See also toText().

Reimplemented in QDomText.

QDomNode QDomNode::lastChild () const [virtual]

Returns the last child of the node. If there is no child node, a null node is returned. Changing the returned node will also change the node in the document tree.

See also firstChild() and childNodes().

QString QDomNode::localName () const [virtual]

If the node uses namespaces, this function returns the local name of the node; otherwise it returns QString::null.

Only nodes of type ElementNode or AttributeNode can have namespaces. A namespace must have been specified at creation time; it is not possible to add a namespace afterwards.

See also prefix(), namespaceURI(), QDomDocument::createElementNS(), and QDomDocument::createAttributeNS().

QDomNode QDomNode::namedItem ( const QString & name ) const

Returns the first direct child node for which nodeName() equals name.

If no such direct child exists, a null node is returned.

See also nodeName().

QString QDomNode::namespaceURI () const [virtual]

Returns the namespace URI of this node or QString::null if the node has no namespace URI.

Only nodes of type ElementNode or AttributeNode can have namespaces. A namespace URI must be specified at creation time and cannot be changed later.

See also prefix(), localName(), QDomDocument::createElementNS(), and QDomDocument::createAttributeNS().

QDomNode QDomNode::nextSibling () const [virtual]

Returns the next sibling in the document tree. Changing the returned node will also change the node in the document tree.

If you have XML like this: 

    <h1>Heading</h1>
    <p>The text...</p>
    <h2>Next heading</h2>
and this QDomNode represents the <p> tag, nextSibling() will return the node representing the <h2> tag.

See also previousSibling().

Example: xml/outliner/outlinetree.cpp.

QString QDomNode::nodeName () const [virtual]

Returns the name of the node.

The meaning of the name depends on the subclass:

Name Meaning
QDomAttr The name of the attribute
QDomCDATASection The string "#cdata-section"
QDomComment The string "#comment"
QDomDocument The string "#document"
QDomDocumentFragment The string "#document-fragment"
QDomDocumentType The name of the document type
QDomElement The tag name
QDomEntity The name of the entity
QDomEntityReference The name of the referenced entity
QDomNotation The name of the notation
QDomProcessingInstruction The target of the processing instruction
QDomText The string "#text"

See also nodeValue().

Example: xml/outliner/outlinetree.cpp.

QDomNode::NodeType QDomNode::nodeType () const [virtual]

Returns the type of the node.

See also toAttr(), toCDATASection(), toDocumentFragment(), toDocument(), toDocumentType(), toElement(), toEntityReference(), toText(), toEntity(), toNotation(), toProcessingInstruction(), toCharacterData(), and toComment().

Reimplemented in QDomDocumentType, QDomDocument, QDomDocumentFragment, QDomCharacterData, QDomAttr, QDomElement, QDomNotation, QDomEntity, QDomEntityReference, and QDomProcessingInstruction.

QString QDomNode::nodeValue () const [virtual]

Returns the value of the node.

The meaning of the value depends on the subclass:

Name Meaning
QDomAttr The attribute value
QDomCDATASection The content of the CDATA section
QDomComment The comment
QDomProcessingInstruction The data of the processing intruction
QDomText The text

All the other subclasses do not have a node value and will return QString::null.

See also setNodeValue() and nodeName().

Example: xml/outliner/outlinetree.cpp.

void QDomNode::normalize () [virtual]

Calling normalize() on an element converts all its children into a standard form. This means that adjacent QDomText objects will be merged into a single text object (QDomCDATASection nodes are not merged).

bool QDomNode::operator!= ( const QDomNode & n ) const

Returns TRUE if n and this DOM node are not equal; otherwise returns FALSE.

QDomNode & QDomNode::operator= ( const QDomNode & n )

Assigns a copy of n to this DOM node.

The data of the copy is shared (shallow copy): modifying one node will also change the other. If you want to make a deep copy, use cloneNode().

bool QDomNode::operator== ( const QDomNode & n ) const

Returns TRUE if n and this DOM node are equal; otherwise returns FALSE.

QDomDocument QDomNode::ownerDocument () const [virtual]

Returns the document to which this node belongs.

QDomNode QDomNode::parentNode () const [virtual]

Returns the parent node. If this node has no parent, a null node is returned (i.e. a node for which isNull() returns TRUE).

QString QDomNode::prefix () const [virtual]

Returns the namespace prefix of the node or QString::null if the node has no namespace prefix.

Only nodes of type ElementNode or AttributeNode can have namespaces. A namespace prefix must be specified at creation time. If a node was created with a namespace prefix, you can change it later with setPrefix().

If you create an element or attribute with QDomDocument::createElement() or QDomDocument::createAttribute(), the prefix will be QString::null. If you use QDomDocument::createElementNS() or QDomDocument::createAttributeNS() instead, the prefix will not be QString::null; but it might be an empty string if the name does not have a prefix.

See also setPrefix(), localName(), namespaceURI(), QDomDocument::createElementNS(), and QDomDocument::createAttributeNS().

QDomNode QDomNode::previousSibling () const [virtual]

Returns the previous sibling in the document tree. Changing the returned node will also change the node in the document tree.

For example, if you have XML like this: 

    <h1>Heading</h1>
    <p>The text...</p>
    <h2>Next heading</h2>
and this QDomNode represents the <p> tag, previousSibling() will return the node representing the <h1> tag.

See also nextSibling().

QDomNode QDomNode::removeChild ( const QDomNode & oldChild ) [virtual]

Removes oldChild from the list of children. oldChild must be a direct child of this node.

Returns a new reference to oldChild on success or a null node on failure.

See also insertBefore(), insertAfter(), replaceChild(), and appendChild().

QDomNode QDomNode::replaceChild ( const QDomNode & newChild, const QDomNode & oldChild ) [virtual]

Replaces oldChild with newChild. oldChild must be a direct child of this node.

If newChild is the child of another node, it is reparented to this node. If newChild is a child of this node, then its position in the list of children is changed.

If newChild is a QDomDocumentFragment, then oldChild is replaced by all of the children of the fragment.

Returns a new reference to oldChild on success or a null node an failure.

See also insertBefore(), insertAfter(), removeChild(), and appendChild().

void QDomNode::save ( QTextStream & str, int indent ) const

Writes the XML representation of the node and all its children to the stream str. This function uses indent as the amount of space to indent the node.

void QDomNode::setNodeValue ( const QString & v ) [virtual]

Sets the node's value to v.

See also nodeValue().

void QDomNode::setPrefix ( const QString & pre ) [virtual]

If the node has a namespace prefix, this function changes the namespace prefix of the node to pre. Otherwise this function does nothing.

Only nodes of type ElementNode or AttributeNode can have namespaces. A namespace prefix must have be specified at creation time; it is not possible to add a namespace prefix afterwards.

See also prefix(), localName(), namespaceURI(), QDomDocument::createElementNS(), and QDomDocument::createAttributeNS().

QDomAttr QDomNode::toAttr ()

Converts a QDomNode into a QDomAttr. If the node is not an attribute, the returned object will be null.

See also isAttr().

QDomCDATASection QDomNode::toCDATASection ()

Converts a QDomNode into a QDomCDATASection. If the node is not a CDATA section, the returned object will be null.

See also isCDATASection().

QDomCharacterData QDomNode::toCharacterData ()

Converts a QDomNode into a QDomCharacterData. If the node is not a character data node the returned object will be null.

See also isCharacterData().

QDomComment QDomNode::toComment ()

Converts a QDomNode into a QDomComment. If the node is not a comment the returned object will be null.

See also isComment().

QDomDocument QDomNode::toDocument ()

Converts a QDomNode into a QDomDocument. If the node is not a document the returned object will be null.

See also isDocument().

QDomDocumentFragment QDomNode::toDocumentFragment ()

Converts a QDomNode into a QDomDocumentFragment. If the node is not a document fragment the returned object will be null.

See also isDocumentFragment().

QDomDocumentType QDomNode::toDocumentType ()

Converts a QDomNode into a QDomDocumentType. If the node is not a document type the returned object will be null.

See also isDocumentType().

QDomElement QDomNode::toElement ()

Converts a QDomNode into a QDomElement. If the node is not an element the returned object will be null.

See also isElement().

Example: xml/outliner/outlinetree.cpp.

QDomEntity QDomNode::toEntity ()

Converts a QDomNode into a QDomEntity. If the node is not an entity the returned object will be null.

See also isEntity().

QDomEntityReference QDomNode::toEntityReference ()

Converts a QDomNode into a QDomEntityReference. If the node is not an entity reference, the returned object will be null.

See also isEntityReference().

QDomNotation QDomNode::toNotation ()

Converts a QDomNode into a QDomNotation. If the node is not a notation the returned object will be null.

See also isNotation().

QDomProcessingInstruction QDomNode::toProcessingInstruction ()

Converts a QDomNode into a QDomProcessingInstruction. If the node is not a processing instruction the returned object will be null.

See also isProcessingInstruction().

QDomText QDomNode::toText ()

Converts a QDomNode into a QDomText. If the node is not a text, the returned object will be null.

See also isText().

Related Functions

QTextStream & operator<< ( QTextStream & str, const QDomNode & node )

Writes the XML representation of the node node and all its children to the stream str.

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