如何在 C# 中使用 XPathEvaluate 方法通过 Xpath 获取节点元素属性的值？

Question

考虑以下 XML 正文；

    <whitelist
              whitelist_entry_nb="4"
              whitelist_size="4000">
              <locations>
                <location
                  path="kate-api.gateway.zigbee-network.components.{component}.whitelist.{whitelist-entry}">
                  <var-fields>
                    <var-field
                      key="component"
                      value="F9BA2F5E2E1EBE1358F70691990F0918" />
                    <var-field
                      key="whitelist-entry"
                      value="8.042620EA5A3380" />
                  </var-fields>
                </location>
            <location
              path="kate-api.gateway.zigbee-network.components.{component}.whitelist.{whitelist-entry}">
              <var-fields>
                <var-field
                  key="component"
                  value="F9BA2F5E2E1EBE1358F70691990F0918" />
                <var-field
                  key="whitelist-entry"
                  value="8.043D147AA44A80" />
              </var-fields>
            </location>
</whitelist>

Xpath 是：

/whitelist/locations/location/var-fields/var-field[@key="whitelist-entry" and @value="8.0440147AA44A80"]

Xpath 结果必须如下：

Element='<var-field key="whitelist-entry" value="8.0440147AA44A80"/>'

我想要做的是将此 xpath 传递给 XPathEvaluate 方法并到达 XPath 结果元素内部的属性值，即“白名单”和“8.0440147AA44A80”。我想检查这些值是否存在于 xml 中。

我正在尝试将此 xpath 传递给 XpathEvaluate 方法，如下所示：

var doc = XDocument.Parse(System.Web.HttpUtility.HtmlDecode(response.Body));
var result = doc.XPathEvaluate(matchString[i].xpath);

*matchString 来自 Json 文件

XPathEvaluate 方法返回一个布尔值、字符串或 IENumerable； 我可以在这里控制布尔结果如下：

if(result is bool){
    resultBool = (bool) result;
    if(resultBool)
    {
        Report.Success("Content " + matchString[i].xpath + "is in reponse");
    }
    else
    {
        Report.Failure("Content " + matchString[i].xpath + "is not in reponse");
    }
}

我希望输出是 Element=''。 我将能够使用 SelectNode 方法等从这里获取属性值。

Answer 1

var match = new Regex("^(.*)\\[@key=\"(.*?)\".*@value=\"(.*?)\"]").Match(matchString[i].xpath);

try
{
    string evaluator = match.Groups[1].Value;    // /whitelist/locations/location/var-fields/var-field
    string target_key = match.Groups[2].Value;   // whitelist-entry
    string target_value = match.Groups[3].Value; // 8.0440147AA44A80

    var doc = XDocument.Parse(System.Web.HttpUtility.HtmlDecode(response.Body));
    var fields = (IEnumerable)doc.XPathEvaluate(evaluator);
    var values = fields.Cast<XElement>()
                           .Select(x => new {
                               key = x.Attribute("key").Value,
                               value = x.Attribute("value").Value
                           }).ToList();

    bool found = false;

    foreach (var val in values)
    {
        if (val.key == target_key && val.value == target_value)
        {
            found = true;
        }
    }

    if(found)
    {
        Report.Success("Content " + matchString[i].xpath + "is in reponse");
    }
    else
    {
        Report.Failure("Content " + matchString[i].xpath + "is not in reponse");
    }
}
catch
{
    //Invalid xPath format
}