QDomNode¶

PyQt5.QtXml.QDomNode: Inherited by QDomAttr, QDomCharacterData, QDomDocument, QDomDocumentFragment, QDomDocumentType, QDomElement, QDomEntity, QDomEntityReference, QDomNotation, QDomProcessingInstruction.

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().

A QDomNode can be null, much like a null pointer. 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.

# 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 Level 1 and Level 2 Core. For a more general introduction of the DOM implementation see the QDomDocument documentation.

Enums¶

EncodingPolicy

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

See also

save().

Member	Value	Description
EncodingFromDocument	1	The encoding is fetched from the document.
EncodingFromTextStream	2	The encoding is fetched from the QTextStream.

NodeType

This enum defines the type of the node:

Member	Value	Description
AttributeNode	TODO	TODO
BaseNode	21	A QDomNode object, i.e. not a QDomNode subclass.
CDATASectionNode	TODO	TODO
CharacterDataNode	TODO	TODO
CommentNode	TODO	TODO
DocumentFragmentNode	TODO	TODO
DocumentNode	TODO	TODO
DocumentTypeNode	TODO	TODO
ElementNode	TODO	TODO
EntityNode	TODO	TODO
EntityReferenceNode	TODO	TODO
NotationNode	TODO	TODO
ProcessingInstructionNode	TODO	TODO
TextNode	TODO	TODO

Methods¶

__init__(): Constructs a isNull() node.

__init__(QDomNode)

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().

appendChild(QDomNode) → 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 isNull() on failure.

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

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

attributes() → QDomNamedNodeMap

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.

childNodes() → QDomNodeList

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(), lastChild().

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: bool = True) → 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() → 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.

See also

lineNumber(), setContent().

__eq__(QDomNode) → bool: TODO

firstChild() → QDomNode: Returns the first child of the node. If there is no child node, a isNull() is returned. Changing the returned node will also change the node in the document tree.

See also

lastChild(), childNodes().

firstChildElement(tagName: str = '') → QDomElement: Returns the first child element with tag name tagName if tagName is non-empty; otherwise returns the first child element. Returns a null element if no such child exists.

See also

lastChildElement(), previousSiblingElement(), nextSiblingElement().

hasAttributes() → bool: Returns true if the node has attributes; otherwise returns false.

See also

attributes().

hasChildNodes() → bool: Returns true if the node has one or more children; otherwise returns false.

insertAfter(QDomNode, QDomNode) → QDomNode

Inserts the node newChild after the child node refChild. refChild must be a direct child of this node. If refChild is isNull() 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 isNull() on failure.

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

insertBefore(QDomNode, QDomNode) → QDomNode

Inserts the node newChild before the child node refChild. refChild must be a direct child of this node. If refChild is isNull() 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 isNull() on failure.

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

isAttr() → 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() → 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() → 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().

See also

toCharacterData().

isComment() → 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() → 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() → 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().

See also

toDocumentFragment().

isDocumentType() → 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() → 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() → 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() → 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().

See also

toEntityReference().

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

isProcessingInstruction() → 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().

See also

toProcessingInstruction().

isSupported(str, str) → 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() → 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() → QDomNode: Returns the last child of the node. If there is no child node, a isNull() is returned. Changing the returned node will also change the node in the document tree.

See also

firstChild(), childNodes().

lastChildElement(tagName: str = '') → QDomElement: Returns the last child element with tag name tagName if tagName is non-empty; otherwise returns the last child element. Returns a null element if no such child exists.

See also

firstChildElement(), previousSiblingElement(), nextSiblingElement().

lineNumber() → 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.

See also

columnNumber(), setContent().

localName() → 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 NodeType or NodeType can have namespaces. A namespace must have been specified at creation time; it is not possible to add a namespace afterwards.

namedItem(str) → QDomNode

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

If no such direct child exists, a isNull() is returned.

See also

nodeName().

namespaceURI() → str

Returns the namespace URI of this node or an empty string if the node has no namespace URI.

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

__ne__(QDomNode) → bool: TODO

nextSibling() → QDomNode

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, will return the node representing the <h2> tag.

See also

previousSibling().

nextSiblingElement(taName: str = '') → QDomElement: Returns the next sibling element with tag name tagName if tagName is non-empty; otherwise returns any next sibling element. Returns a null element if no such sibling exists.

See also

firstChildElement(), previousSiblingElement(), lastChildElement().

nodeName() → 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() → NodeType: Returns the type of the node.

See also

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

nodeValue() → 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.

See also

setNodeValue(), nodeName().

normalize(): Calling 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).

ownerDocument() → QDomDocument: Returns the document to which this node belongs.

parentNode() → 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() → str

Returns the namespace prefix of the node or an empty string if the node has no namespace prefix.

Only nodes of type NodeType or NodeType 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() → QDomNode

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, will return the node representing the <h1> tag.

See also

nextSibling().

previousSiblingElement(tagName: str = '') → QDomElement: Returns the previous sibilng element with tag name tagName if tagName is non-empty; otherwise returns any previous sibling element. Returns a null element if no such sibling exists.

See also

firstChildElement(), nextSiblingElement(), lastChildElement().

removeChild(QDomNode) → 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 isNull() on failure.

replaceChild(QDomNode, QDomNode) → 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 isNull() on failure.

save(QTextStream, int, EncodingPolicy)

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(str): Sets the node’s value to v.

See also

nodeValue().

setPrefix(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 NodeType or NodeType can have namespaces. A namespace prefix must have be specified at creation time; it is not possible to add a namespace prefix afterwards.

toAttr() → QDomAttr: Converts a QDomNode into a QDomAttr. If the node is not an attribute, the returned object will be isNull().

See also

isAttr().

toCDATASection() → QDomCDATASection: Converts a QDomNode into a QDomCDATASection. If the node is not a CDATA section, the returned object will be isNull().

See also

isCDATASection().

toCharacterData() → QDomCharacterData: Converts a QDomNode into a QDomCharacterData. If the node is not a character data node the returned object will be isNull().

See also

isCharacterData().

toComment() → QDomComment: Converts a QDomNode into a QDomComment. If the node is not a comment the returned object will be isNull().

See also

isComment().

toDocument() → QDomDocument: Converts a QDomNode into a QDomDocument. If the node is not a document the returned object will be isNull().

See also

isDocument().

toDocumentFragment() → QDomDocumentFragment: Converts a QDomNode into a QDomDocumentFragment. If the node is not a document fragment the returned object will be isNull().

See also

isDocumentFragment().

toDocumentType() → QDomDocumentType: Converts a QDomNode into a QDomDocumentType. If the node is not a document type the returned object will be isNull().

See also

isDocumentType().

toElement() → QDomElement: Converts a QDomNode into a QDomElement. If the node is not an element the returned object will be isNull().

See also

isElement().

toEntity() → QDomEntity: Converts a QDomNode into a QDomEntity. If the node is not an entity the returned object will be isNull().

See also

isEntity().

toEntityReference() → QDomEntityReference: Converts a QDomNode into a QDomEntityReference. If the node is not an entity reference, the returned object will be isNull().

See also

isEntityReference().

toNotation() → QDomNotation: Converts a QDomNode into a QDomNotation. If the node is not a notation the returned object will be isNull().

See also

isNotation().

toProcessingInstruction() → QDomProcessingInstruction: Converts a QDomNode into a QDomProcessingInstruction. If the node is not a processing instruction the returned object will be isNull().

See also

isProcessingInstruction().

toText() → QDomText: Converts a QDomNode into a QDomText. If the node is not a text, the returned object will be isNull().

See also

isText().