Question

我在使用XPath时遇到了一些麻烦。

我想要做的是从货币国家/地区代码中提取汇率。

我的带有当前的XML就在这里：http://www.nationalbanken.dk/dndk/valuta.nsf/valuta.xml

这是我的疑问：

query = xml.XPathSelectElement(**"exhangerates/dailyrates/currency[@code='"+ country +"']@rate"**).Value;

我正在使用.NET 3.5和一个asp webservice项目，它会产生以下错误：

System.Xml.XPath.XPathException: 'exhangerates/dailyrates/currency[@code='USD']@rate' has an invalid token.
   at MS.Internal.Xml.XPath.XPathParser.ParseXPathExpresion(String xpathExpresion)
   at MS.Internal.Xml.XPath.QueryBuilder.Build(String query, Boolean allowVar, Boolean allowKey)
   at MS.Internal.Xml.XPath.QueryBuilder.Build(String query, Boolean& needContext)
   at System.Xml.XPath.XPathExpression.Compile(String xpath, IXmlNamespaceResolver nsResolver)
   at System.Xml.XPath.XPathNavigator.Evaluate(String xpath, IXmlNamespaceResolver resolver)
   at System.Xml.XPath.XPathEvaluator.Evaluate[T](XNode node, String expression, IXmlNamespaceResolver resolver)
   at System.Xml.XPath.Extensions.XPathSelectElements(XNode node, String expression, IXmlNamespaceResolver resolver)
   at System.Xml.XPath.Extensions.XPathSelectElement(XNode node, String expression)
   at WebServiceCurrency.Service1.RetrieveExchangeRate(String country) in c:\Users\Peter\Documents\GitHub\HotMess\C#\Webservices\WebServiceCurrency\WebServiceCurrency\Service1.asmx.cs:line 35

Answer 1

这有效：

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

   <xsl:value-of select="//dailyrates/currency[@code='USD']/@rate" />

 </xsl:template>
</xsl:stylesheet>

输出：

566,97

所以你的解决方案应该是

query = xml.XPathSelectElement(**"exhangerates/dailyrates/currency[@code='"+ country +"']/@rate"**).Value;

Answer 2

您的错误消息试图告诉您XPath有语法错误。对于

"exhangerates/dailyrates/currency[@code='"+ country +"']@rate"

读

"exhangerates/dailyrates/currency[@code='"+ country +"']/@rate"

也就是说，在导航到currency节点的步骤和导航到其rate属性的后续步骤之间插入斜杠。（我看到PCM打败了我这个解决方案。帽子。）

XPath属性查询和检索

2 个答案: