XPath - 根据以下同级选择节点

Question

我有一个这样的查询：

/plist/dict[1]/dict/dict/dict/key/following-sibling::dict/string[string()='Algier']

我真正想要选择的是“关键”节点（就在以下同级::字典之前）。

xml是这样的：

<?xml version="1.0" encoding="UTF-8"?>
<plist version="1.0">
    <dict>
    <key>en_GB</key>
            <dict>
                <key>Africa</key>
                <dict>
                    <key>Algeria</key>
                    <dict>
                        <key>60390</key>
                        <dict>
                            <key>NAME</key>
                            <string>Algier</string>
                            <key>LATITUDE</key>
                            <string>36.7500</string>
                            <key>LONGITUDE</key>
                            <string>3.0500</string>
                        </dict>
                        <key>60391</key>
                        <dict>
                            <key>NAME</key>
                            <string>Some other city</string>
                            <key>LATITUDE</key>
                            <string>36.7500</string>
                            <key>LONGITUDE</key>
                            <string>3.0500</string>
                        </dict>
                    </dict>
                </dict>
        </dict>
    </dict>
</plist>

换句话说，当城市名称是“阿尔及尔”时，我想选择“60390”，或者（当城市名称是“其他城市”时，我想选择60391）。

我在 QML XmlListModel 中执行此操作。

更新了代码 使用的 QML：

import QtQuick 1.0

Rectangle {
    id: container;
    width: 360
    height: 360

    function onLocationModelLoaded(){
        console.debug(weLocationModel.count);
    }

    XmlListModel{
        id: weLocationModel;
        source: "we_locations.plist";
        query: "/*/dict/dict/dict/dict/key[following-sibling::dict[1]/key[.='NAME' and following-sibling::string[1] = 'Algier']]"

        XmlRole{
            name: "cityId";
            query: "name()";
        }
        onStatusChanged: {
            if (status == XmlListModel.Ready){
                console.debug("Location Model Ready");
                container.onLocationModelLoaded();
            }
        }
    }
}

似乎嵌套的 following-sibling 不起作用。 例如：

query: "/*/dict/dict/dict/dict/key[following-sibling::dict[1]/key[.='NAME']]"

这两个总是返回：

Error XPST0003 in file:///Users/Ali/qtprojects/welocationtest-build-simulator/welocationtest.app/Contents/MacOS/welocationtest, at line 2, column 97: syntax error, unexpected ], expecting )
Error XPST0003 in file:///Users/Ali/qtprojects/welocationtest-build-simulator/welocationtest.app/Contents/MacOS/welocationtest, at line 2, column 91: syntax error, unexpected ], expecting end of file
file:///Users/Ali/qtprojects/welocationtest-build-simulator/welocationtest.app/Contents/Resources/qml/welocationtest/main.qml:17:9: QML XmlRole: invalid query: "name()"
Location Model Ready
0

QML 可能不遵循 XPath 标准吗？该解决方案适用于所有其他路径编辑器。

Answer 1

精确选择所需 key 元素的 XPath 表达式如下：

   /*/dict/dict/dict/dict
     /key
        [following-sibling::dict[1]/key
                  [.='NAME'
                 and
                   following-sibling::string[1] = $pCity
                  ]
        ]

当 $pCity 设置/替换为 "Algier" 时，此 XPath 表达式选择：

<key>60390</key>

当 $pCity 设置/替换为 “其他城市” 时，此 XPath 表达式选择：

<key>60391</key>

基于 XSLT 的验证：

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>

 <xsl:param name="pCity" select="'Some other city'"/>

 <xsl:template match="/">
  <xsl:copy-of select=
  "/*/dict/dict/dict/dict
     /key
        [following-sibling::dict[1]/key
                  [.='NAME'
                 and
                   following-sibling::string[1] = $pCity
                  ]
        ]
  "/>
 </xsl:template>
</xsl:stylesheet>

当这个对提供的 XML 文档应用转换：

<plist version="1.0">
    <dict>
        <key>en_GB</key>
        <dict>
            <key>Africa</key>
            <dict>
                <key>Algeria</key>
                <dict>
                    <key>60390</key>
                    <dict>
                        <key>NAME</key>
                        <string>Algier</string>
                        <key>LATITUDE</key>
                        <string>36.7500</string>
                        <key>LONGITUDE</key>
                        <string>3.0500</string>
                    </dict>
                    <key>60391</key>
                    <dict>
                        <key>NAME</key>
                        <string>Some other city</string>
                        <key>LATITUDE</key>
                        <string>36.7500</string>
                        <key>LONGITUDE</key>
                        <string>3.0500</string>
                    </dict>
                </dict>
            </dict>
        </dict>
    </dict>
</plist>

生成所需的正确结果：

<key>60391</key>

当我们在上述转换中替换时：

 <xsl:param name="pCity" select="'Some other city'"/>

替换为：

 <xsl:param name="pCity" select="'Algier'"/>

再次应用转换，然后我们再次得到正确的结果：

<key>60390</key>

Answer 2

要获取城市的号码，您也可以使用正则表达式（特别是在 QML XPath 支持不够好的情况下）：

import QtQuick 1.0

Rectangle {
    id: container

    width: 360
    height: 360

    Component.onCompleted: {
        loadWeLocationsFile();
    }

    property string weLocationsXML
    signal weLocationsLoaded()

    function loadWeLocationsFile() {
        // load file
        var doc = new XMLHttpRequest();
        doc.onreadystatechange = function() {
            if (doc.readyState == XMLHttpRequest.DONE) {
                // get file content
                weLocationsXML = doc.responseText;

                // emit signal
                weLocationsLoaded();
            }
        }

        doc.open("GET", "we_locations.plist");
        doc.send();
    }

    function getIDByName(name) {
        // escape special characters for regex (maybe there is a better way to do this)
        var safeName = name.replace(/[-.,?+*#^$()[\]{}\\|]/g, "\\
amp;");

        // create regex
        var regex = new RegExp("<key>(.*?)</key>\\s*<dict>\\s*<key>NAME</key>\\s*<string>" + safeName + "</string>", "m");

        // execute regex
        var match = regex.exec(weLocationsXML);

        if (match != null && match.length > 1) {
            return match[1];  // name found, group 1 contains id
        } else {
            return null;  // no such name in XML
        }
    }

    // Test it ...
    onWeLocationsLoaded: {
        console.log("Number for 'Algier':", getIDByName("Algier"));
        console.log("Number for 'NotInXML':", getIDByName("NotInXML"));
        console.log("Number for 'Some other city':", getIDByName("Some other city"));
    }
}

输出：

Number for 'Algier': 60390
Number for 'NotInXML': null
Number for 'Some other city': 60391

如果您需要 QML 模型中的号码，您可以创建一个 ListModel 并向其中添加数字。