class QDomNode

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

Inherited by: QDomProcessingInstruction, QDomNotation, QDomEntityReference, QDomEntity, QDomElement, QDomDocumentType, QDomDocumentFragment, QDomDocument, QDomCharacterData, QDomText, QDomComment, QDomCDATASection, QDomAttr

Synopsis

Methods

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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() .

A QDomNode can be null, much like None. Creating a copy of a null node results in another null node. It is not possible to modify a null node, but it is possible to assign another, possibly non-null node to it. In this case, the copy of the null node will remain null. You can check if a QDomNode is null by calling isNull() . The empty constructor of a QDomNode (or any of the derived classes) creates a null node.

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.

d = QDomDocument()
someXML = QString()
d.setContent(someXML)
n = d.firstChild()
while not n.isNull():
    if n.isElement():
        e = n.toElement()
        print("Element name: ", qPrintable(e.tagName()), '\n')
        break

    n = n.nextSibling()

For further information about the Document Object Model see Level 1 and Level 2 Core . For a more general introduction of the DOM implementation see the QDomDocument documentation.

class NodeType

This enum defines the type of the node:

Constant

Description

QDomNode.ElementNode

QDomNode.AttributeNode

QDomNode.TextNode

QDomNode.CDATASectionNode

QDomNode.EntityReferenceNode

QDomNode.EntityNode

QDomNode.ProcessingInstructionNode

QDomNode.CommentNode

QDomNode.DocumentNode

QDomNode.DocumentTypeNode

QDomNode.DocumentFragmentNode

QDomNode.NotationNode

QDomNode.BaseNode

A QDomNode object, i.e. not a QDomNode subclass.

QDomNode.CharacterDataNode
class EncodingPolicy

This enum specifies how save() determines what encoding to use when serializing.

Constant

Description

QDomNode.EncodingFromDocument

The encoding is fetched from the document.

QDomNode.EncodingFromTextStream

The encoding is fetched from the QTextStream.

See also

save()

__init__()

Constructs a null node.

__init__(node)
Parameters:

node – QDomNode

Constructs a copy of 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() .

appendChild(newChild)
Parameters:

newChild – QDomNode

Return type:

QDomNode

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.

If newChild is a QDomElement and this node is a QDomDocument that already has an element node as a child, newChild is not added as a child and a null node is returned.

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

Calling this function on a null node(created, for example, with the default constructor) does nothing and returns a null node .

The DOM specification disallow inserting attribute nodes, but for historical reasons, QDom accepts them anyway.

attributes()
Return type:

QDomNamedNodeMap

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

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

childNodes()
Return type:

QDomNodeList

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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 &lt;h1&gt; tag and the node created by the &lt;p&gt; tag.

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

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()

cloneNode([deep=true])
Parameters:

deep – bool

Return type:

QDomNode

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.

columnNumber()
Return type:

int

For nodes created by setContent() , this function returns the column number in the XML document where the node was parsed. Otherwise, -1 is returned.

firstChild()
Return type:

QDomNode

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.

firstChildElement([tagName=""[, namespaceURI=""]])
Parameters:

  • tagName – str

  • namespaceURI – str

Return type:

QDomElement

Returns the first child element with tag name tagName and namespace URI namespaceURI. If tagName is empty, returns the first child element with namespaceURI, and if namespaceURI is empty, returns the first child element with tagName. If the both parameters are empty, returns the first child element. Returns a null element if no such child exists.

hasAttributes()
Return type:

bool

Returns true if the node has attributes; otherwise returns false.

See also

attributes()

hasChildNodes()
Return type:

bool

Returns true if the node has one or more children; otherwise returns false.

insertAfter(newChild, refChild)
Parameters:
Return type:

QDomNode

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.

The DOM specification disallow inserting attribute nodes, but due to historical reasons QDom accept them nevertheless.

insertBefore(newChild, refChild)
Parameters:
Return type:

QDomNode

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.

The DOM specification disallow inserting attribute nodes, but due to historical reasons QDom accept them nevertheless.

isAttr()
Return type:

bool

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()

isCDATASection()
Return type:

bool

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()

isCharacterData()
Return type:

bool

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() .

isComment()
Return type:

bool

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()

isDocument()
Return type:

bool

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()

isDocumentFragment()
Return type:

bool

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() .

isDocumentType()
Return type:

bool

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()

isElement()
Return type:

bool

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()

isEntity()
Return type:

bool

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()

isEntityReference()
Return type:

bool

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() .

isNotation()
Return type:

bool

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()

isNull()
Return type:

bool

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

isProcessingInstruction()
Return type:

bool

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() .

isSupported(feature, version)
Parameters:

  • feature – str

  • version – str

Return type:

bool

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

hasFeature()

isText()
Return type:

bool

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()

lastChild()
Return type:

QDomNode

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.

lastChildElement([tagName=""[, namespaceURI=""]])
Parameters:

  • tagName – str

  • namespaceURI – str

Return type:

QDomElement

Returns the last child element with tag name tagName and namespace URI namespaceURI. If tagName is empty, returns the last child element with namespaceURI, and if namespaceURI is empty, returns the last child element with tagName. If the both parameters are empty, returns the last child element. Returns a null element if no such child exists.

lineNumber()
Return type:

int

For nodes created by setContent() , this function returns the line number in the XML document where the node was parsed. Otherwise, -1 is returned.

localName()
Return type:

str

If the node uses namespaces, this function returns the local name of the node; otherwise it returns an empty string.

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.

namedItem(name)
Parameters:

name – str

Return type:

QDomNode

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()

namespaceURI()
Return type:

str

Returns the namespace URI of this node or an empty string 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.

nextSibling()
Return type:

QDomNode

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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.

nextSiblingElement([taName=""[, namespaceURI=""]])
Parameters:

  • taName – str

  • namespaceURI – str

Return type:

QDomElement

Returns the next sibling element with tag name tagName and namespace URI namespaceURI. If tagName is empty, returns the next sibling element with namespaceURI, and if namespaceURI is empty, returns the next sibling child element with tagName. If the both parameters are empty, returns the next sibling element. Returns a null element if no such sibling exists.

nodeName()
Return type:

str

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”

Note

This function does not take the presence of namespaces into account when processing the names of element and attribute nodes. As a result, the returned name can contain any namespace prefix that may be present. To obtain the node name of an element or attribute, use localName() ; to obtain the namespace prefix, use namespaceURI() .

See also

nodeValue()

nodeType()
Return type:

NodeType

Returns the type of the node.

nodeValue()
Return type:

str

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 instruction

QDomText

The text

All the other subclasses do not have a node value and will return an empty string.

normalize()

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).

__ne__(other)
Parameters:

other – QDomNode

Return type:

bool

Returns true if other and this DOM node are not equal; otherwise returns false.

__eq__(other)
Parameters:

other – QDomNode

Return type:

bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns true if other and this DOM node are equal; otherwise returns false.

Any instance of QDomNode acts as a reference to an underlying data structure in QDomDocument . The test for equality checks if the two references point to the same underlying node. For example:

document = QDomDocument()
element1 = document.documentElement()
element2 = element1

The two nodes ( QDomElement is a QDomNode subclass) both refer to the document’s root element, and element1 == element2 will return true. On the other hand:

element3 = document.createElement("MyElement")
element4 = document.createElement("MyElement")

Even though both nodes are empty elements carrying the same name, element3 == element4 will return false because they refer to two different nodes in the underlying data structure.

ownerDocument()
Return type:

QDomDocument

Returns the document to which this node belongs.

parentNode()
Return type:

QDomNode

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

prefix()
Return type:

str

Returns the namespace prefix of the node or an empty string 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 createElement() or createAttribute() , the prefix will be an empty string. If you use createElementNS() or createAttributeNS() instead, the prefix will not be an empty string; but it might be an empty string if the name does not have a prefix.

previousSibling()
Return type:

QDomNode

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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 &lt;p&gt; tag, previousSibling() will return the node representing the &lt;h1&gt; tag.

See also

nextSibling()

previousSiblingElement([tagName=""[, namespaceURI=""]])
Parameters:

  • tagName – str

  • namespaceURI – str

Return type:

QDomElement

Returns the previous sibling element with tag name tagName and namespace URI namespaceURI. If tagName is empty, returns the previous sibling element with namespaceURI, and if namespaceURI is empty, returns the previous sibling element with tagName. If the both parameters are empty, returns the previous sibling element. Returns a null element if no such sibling exists.

removeChild(oldChild)
Parameters:

oldChild – QDomNode

Return type:

QDomNode

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.

replaceChild(newChild, oldChild)
Parameters:
Return type:

QDomNode

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 on failure.

save(arg__1, arg__2[, arg__3=QDomNode.EncodingFromDocument])
Parameters:

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

If the document contains invalid XML characters or characters that cannot be encoded in the given encoding, the result and behavior is undefined.

If encodingPolicy is EncodingFromDocument and this node is a document node, the encoding of text stream stream's encoding is set by treating a processing instruction by name “xml” as an XML declaration, if one exists, and otherwise defaults to UTF-8. XML declarations are not processing instructions, but this behavior exists for historical reasons. If this node is not a document node, the text stream’s encoding is used.

If encodingPolicy is EncodingFromTextStream and this node is a document node, this function behaves as save(QTextStream &str, int indent) with the exception that the encoding specified in the text stream stream is used.

If the document contains invalid XML characters or characters that cannot be encoded in the given encoding, the result and behavior is undefined.

setNodeValue(value)
Parameters:

value – str

Sets the node’s value to value.

See also

nodeValue()

setPrefix(pre)
Parameters:

pre – str

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.

toAttr()
Return type:

QDomAttr

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

See also

isAttr()

toCDATASection()
Return type:

QDomCDATASection

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

See also

isCDATASection()

toCharacterData()
Return type:

QDomCharacterData

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

toComment()
Return type:

QDomComment

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

See also

isComment()

toDocument()
Return type:

QDomDocument

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

See also

isDocument()

toDocumentFragment()
Return type:

QDomDocumentFragment

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

toDocumentType()
Return type:

QDomDocumentType

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

See also

isDocumentType()

toElement()
Return type:

QDomElement

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

See also

isElement()

toEntity()
Return type:

QDomEntity

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

See also

isEntity()

toEntityReference()
Return type:

QDomEntityReference

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

toNotation()
Return type:

QDomNotation

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

See also

isNotation()

toProcessingInstruction()
Return type:

QDomProcessingInstruction

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

toText()
Return type:

QDomText

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

See also

isText()