通过有效的xpath在XmlDocument.SelectSingleNode上返回null

Question

我目前有以下代码

nsmgr = new XmlNamespaceManager(xmlDoc.NameTable);
nsmgr.AddNamespace("soapenv", soapenv_namespace);
nsmgr.AddNamespace("de", de_namespace);

XmlNode xnEnvelope = xmlDoc.SelectSingleNode("//soapenv:Envelope", nsmgr);
XmlNode xnBody = xmlDoc.SelectSingleNode("//soapenv:Envelope/soapenv:Body", nsmgr);
XmlNode xnMessage = xnBody.SelectSingleNode("//soapenv:Envelope/soapenv:Body/message", nsmgr);

解析以下xml（出于可读性而截断）

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
     <soapenv:Body>
        <message     xmlns="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractDetailResponse"     xmlns:ns2="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractReferenceResponse" xmlns:ns3="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractRequest" xmlns:ns4="http://www.origostandards.com/schema/tech/v1.0/SOAPFaultDetail">
        <de:m_content .....

问题是XmlNode xnMessage = xnBody.SelectSingleNode（“ // soapenv：Envelope / soapenv：Body / message”，nsmgr）行； 当我期望它返回message元素时，返回null。

我高度怀疑它与我配置的空白名称空间有关，但我找不到正确的值组合来使其正常工作。

任何指针将不胜感激。

Answer 1

您在此处引入了默认名称空间 ：

xmlns="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractDetailResponse" 

这将导致message元素及其所有不带前缀的后代被识别为该默认名称空间（除非后代元素具有本地默认名称空间）。 要访问默认名称空间中的元素，只需注册一个前缀（例如d ，然后将其映射到默认名称空间uri：

nsmgr.AddNamespace("d", "http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractDetailResponse");

然后在XPath表达式中相应地使用新注册的前缀：

XmlNode xnBody = xmlDoc.SelectSingleNode("//soapenv:Envelope/soapenv:Body", nsmgr);
XmlNode xnMessage = xnBody.SelectSingleNode("d:message", nsmgr);

Answer 2

这工作

XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(@"C:\Users\DummyUser\Desktop\Noname1.xml");

XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmlDoc.NameTable);
nsmgr.AddNamespace("soapenv", "http://schemas.xmlsoap.org/soap/envelope/");
nsmgr.AddNamespace("de", "http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractDetailResponse");

XmlNode xnEnvelope = xmlDoc.SelectSingleNode("//soapenv:Envelope", nsmgr);
XmlNode xnBody = xnEnvelope.SelectSingleNode("//soapenv:Body", nsmgr);
XmlNode xnMessage = xnBody.SelectSingleNode("de:message", nsmgr);

和xml文件是

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
 <soapenv:Body>
    <message xmlns="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractDetailResponse"     xmlns:ns2="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractReferenceResponse" 
    xmlns:ns3="http://www.origostandards.com/schema/ce/v2.1/CEBondSingleContractRequest" 
    xmlns:ns4="http://www.origostandards.com/schema/tech/v1.0/SOAPFaultDetail">
    This is my sample message
    </message>
</soapenv:Body>
</soapenv:Envelope>