QXmlNodeModelIndex ¶

概要 ¶

详细描述 ¶

QXmlNodeModelIndex is an index into an XML node model . It contains:

• A pointer to an XML node model , which is returned by model() ，和

• Some data, which is returned by data() , internalPointer() ，和 additionalData() .

因为 QXmlNodeModelIndex is intentionally a simple class, it doesn’t have member functions for accessing the properties of nodes. For example, it doesn’t have functions for getting a node’s name or its list of attributes or child nodes. If you find that you need to retrieve this kind of information from your query results, there are two ways to proceed.

• Send the output of your XQuery to an XML receiver ，或

• Let your XQuery do all the work to produce the desired result.

The second case is explained by example. Suppose you want to populate a list widget with the values of certain attributes from a set of result elements. You could write an XQuery to return the set of elements, and then you would write the code to iterate over the result elements, get their attributes, and extract the desired string values. But the simpler way is to just augment your XQuery to finding the desired attribute values. Then all you have to do is evaluate the XQuery using the version of evaluateTo() that populates a QStringList , which you can send directly to your widget.

QXmlNodeModelIndex doesn’t impose any restrictions on the data value an QXmlNodeModelIndex should contain. The meaning of the data left to the associated node model . Because QXmlNodeModelIndex depends on a particular subclass of QAbstractXmlNodeModel for its existence, the only way you can create an instance of QXmlNodeModelIndex is by asking the node model to create one for you with createIndex() . Since that function is protected, it is usually a good idea to write a public function that creates a QXmlNodeModelIndex from arguments that are appropriate for your particular node model.

A default constructed node index is said to be null, i.e., isNull() returns true.

QXmlNodeModelIndex and QAbstractXmlNodeModel follow the same design pattern used for QModelIndex and QAbstractItemModel .

class QXmlNodeModelIndex ¶

QXmlNodeModelIndex(other)

param other

QXmlNodeModelIndex

Default constructor. Creates an item that is null .

另请参阅

isNull()

PySide2.QtXmlPatterns.QXmlNodeModelIndex. 常量 ¶

常量	描述
QXmlNodeModelIndex.ForwardAxis	All forward axes include this flag.
QXmlNodeModelIndex.ReverseAxis	All reverse axes include this flag.

PySide2.QtXmlPatterns.QXmlNodeModelIndex. NodeKind ¶

Identifies a kind of node.

常量	描述
QXmlNodeModelIndex.Attribute	Identifies an attribute node
QXmlNodeModelIndex.Text	Identifies a text node
QXmlNodeModelIndex.Comment	Identifies a comment node
QXmlNodeModelIndex.Document	Identifies a document node
QXmlNodeModelIndex.Element	Identifies an element node
QXmlNodeModelIndex.Namespace	Identifies a namespace node
QXmlNodeModelIndex.ProcessingInstruction	Identifies a processing instruction.

Note that the optional XML declaration at very beginning of the XML document is not a processing instruction

另请参阅

kind()

PySide2.QtXmlPatterns.QXmlNodeModelIndex. DocumentOrder ¶

Identifies the specific node comparison operator that should be used.

常量	描述
QXmlNodeModelIndex.Precedes	Signifies the \<\< operator. Test whether the first operand precedes the second in the document.
QXmlNodeModelIndex.Follows	Signifies the \>\> operator. Test whether the first operand follows the second in the document.
QXmlNodeModelIndex.Is	Signifies the is operator. Test whether two nodes have the same node identity.

PySide2.QtXmlPatterns.QXmlNodeModelIndex. additionalData ( ) ¶

返回类型

qint64

Returns the second data value. The node index holds two data values. data() returns the first one.

另请参阅

data()

PySide2.QtXmlPatterns.QXmlNodeModelIndex. data ( ) ¶

返回类型

qint64

Returns the first data value. The node index holds two data values. additionalData() returns the second one.

另请参阅

additionalData()

PySide2.QtXmlPatterns.QXmlNodeModelIndex. internalPointer ( ) ¶

返回类型

void

Returns the first data value as a void* pointer.

另请参阅

additionalData()

PySide2.QtXmlPatterns.QXmlNodeModelIndex. isNull ( ) ¶

返回类型

bool

返回 true，若此 QXmlNodeModelIndex is a default constructed value, otherwise false.

A null QXmlNodeModelIndex doesn’t represent any node and cannot be used in conjunction with QAbstractXmlNodeModel .

PySide2.QtXmlPatterns.QXmlNodeModelIndex. model ( ) ¶

返回类型

QAbstractXmlNodeModel

返回 QAbstractXmlNodeModel that this node index refers to. QXmlNodeModelIndex does not own QAbstractXmlNodeModel and does not keep track of its lifetime, so this pointer will dangle if the QAbstractXmlNodeModel is deallocated first.

There is no setter for the node model because instances of QXmlNodeModelIndex instances are only created with createIndex() .

PySide2.QtXmlPatterns.QXmlNodeModelIndex. __ne__ ( other ) ¶

参数

other – QXmlNodeModelIndex

返回类型

bool

返回 true 若 other is the same node as this.

PySide2.QtXmlPatterns.QXmlNodeModelIndex. __eq__ ( other ) ¶

参数

other – QXmlNodeModelIndex

返回类型

bool

Returns true if this node is the same as other . This operator does not compare values, children, or names of nodes. It compares node identities, i.e., whether two nodes are from the same document and are found at the exact same place.