XmlRole QML Type

For specifying a role to an XmlListModel. More...

Import Statement: import QtQuick.XmlListModel 2.12

Properties

Detailed Description

See also Qt QML.

Property Documentation

isKey : bool

Defines whether this is a key role. Key roles are used to determine whether a set of values should be updated or added to the XML list model when XmlListModel::reload() is called.

See also XmlListModel.


name : string

The name for the role. This name is used to access the model data for this role.

For example, the following model has a role named "title", which can be accessed from the view's delegate:

XmlListModel {
    id: xmlModel
    // ...
    XmlRole {
        name: "title"
        query: "title/string()"
    }
}
ListView {
    model: xmlModel
    delegate: Text { text: title }
}

query : string

The relative XPath expression query for this role. The query must be relative; it cannot start with a '/'.

For example, if there is an XML document like this:

Here are some valid XPath expressions for XmlRole queries on this document:

XmlListModel {
    id: model
    ...
    // XmlRole queries will be made on <book> elements
    query: "/catalog/book"

    // query the book title
    XmlRole { name: "title"; query: "title/string()" }

    // query the book's year
    XmlRole { name: "year"; query: "year/number()" }

    // query the book's type (the '@' indicates 'type' is an attribute, not an element)
    XmlRole { name: "type"; query: "@type/string()" }

    // query the book's first listed author (note in XPath the first index is 1, not 0)
    XmlRole { name: "first_author"; query: "author[1]/string()" }

    // query the wanted attribute as a boolean
    XmlRole { name: "wanted"; query: "boolean(@wanted)" }
}

Accessing the model data for the above roles from a delegate:

ListView {
    width: 300; height: 200
    model: model
    delegate: Column {
        Text { text: title + " (" + type + ")"; font.bold: wanted }
        Text { text: first_author }
        Text { text: year }
    }

See the W3C XPath 2.0 specification for more information.


© 2021 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.