XmlListModel QML 类型

For specifying a read-only model using XML data. 更多...

import 语句：

import QtQml.XmlListModel

所有成员列表，包括继承成员

特性

count : int
progress : real
query : string
roles : list<XmlListModelRole>
source : url
status : enumeration

方法

errorString ()
reload ()

详细描述

To use this element, you will need to import the module with the following line:

import QtQml.XmlListModel

XmlListModel is used to create a read-only model from XML data. It can be used as a data source for view elements (such as ListView, PathView, GridView) and other elements that interact with model data (such as Repeater).

注意： This model does not support the XPath queries. It supports simple slash-separated paths and, optionally, one attribute for each element.

For example, if there is an XML document at https://www.qt.io/blog/rss.xml like this:

<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0">
  ...
  <channel>
    <item>
      <title>Qt 6.0.2 Released</title>
      <link>https://www.qt.io/blog/qt-6.0.2-released</link>
      <pubDate>Wed, 03 Mar 2021 12:40:43 GMT</pubDate>
    </item>
    <item>
      <title>Qt 6.1 Beta Released</title>
      <link>https://www.qt.io/blog/qt-6.1-beta-released</link>
      <pubDate>Tue, 02 Mar 2021 13:05:47 GMT</pubDate>
    </item>
    <item>
      <title>Qt Creator 4.14.1 released</title>
      <link>https://www.qt.io/blog/qt-creator-4.14.1-released</link>
      <pubDate>Wed, 24 Feb 2021 13:53:21 GMT</pubDate>
    </item>
  </channel>
</rss>

A XmlListModel could create a model from this data, like this:

import QtQml.XmlListModel
XmlListModel {
    id: xmlModel
    source: "https://www.qt.io/blog/rss.xml"
    query: "/rss/channel/item"
    XmlListModelRole { name: "title"; elementName: "title" }
    XmlListModelRole { name: "pubDate"; elementName: "pubDate" }
    XmlListModelRole { name: "link"; elementName: "link" }
}

query value of "/rss/channel/item" specifies that the XmlListModel should generate a model item for each <item> 在 XML 文档。

XmlListModelRole objects define the model item attributes. Here, each model item will have title , pubDate and link attributes that match the title , pubDate and link values of its corresponding <item> 。(见 XmlListModelRole documentation for more examples.)

The model could be used in a ListView, like this:

ListView {
    width: 180; height: 300
    model: xmlModel
    delegate: Text { text: title + ": " + pubDate + "; link: " + link }
}

XmlListModel data is loaded asynchronously, and status 被设为 XmlListModel.Ready when loading is complete. Note this means when XmlListModel is used for a view, the view is not populated until the model is loaded.

特性文档编制

count : int

The number of data entries in the model.

progress : real

This indicates the current progress of the downloading of the XML data source. This value ranges from 0.0 (no data downloaded) to 1.0 (all data downloaded). If the XML data is not from a remote source, the progress becomes 1.0 as soon as the data is read.

Note that when the progress is 1.0, the XML data has been downloaded, but it is yet to be loaded into the model at this point. Use the status property to find out when the XML data has been read and loaded into the model.

另请参阅 status and source .

query : string

A string representing the base path for creating model items from this model's XmlListModelRole objects. The query should start with '/' .

roles : list < XmlListModelRole >

The roles to make available for this model.

source : url

The location of the XML data source.

status : enumeration

Specifies the model loading status, which can be one of the following:

XmlListModel .Null - No XML data has been set for this model.
XmlListModel .Ready - The XML data has been loaded into the model.
XmlListModel .Loading - The model is in the process of reading and loading XML data.
XmlListModel .Error - An error occurred while the model was loading. See errorString() for details about the error.

另请参阅 progress .

方法文档编制

errorString ()

Returns a string description of the last error that occurred if status is XmlListModel .Error.

reload ()

重新加载模型。