我有一个函数可以检索XML节点中属性的schedule->command('command Name')
->cron( \Carbon\Carbon::parse( $collection->expires_at )->format( 'i h d m' ) . ' *' );
：
UUID.randomUUID().toString().substring(0, 4)
.InnerText在静态 string getPropertyFromNode_string(XmlNode node, string propertyName)
{
try
{
string selectString = "./empty:content/m:properties/d:";
return node.SelectSingleNode(selectString + propertyName, Utils.nmREST).InnerText;
}
catch (Exception exception)
{
Console.WriteLine(exception.Message);
throw exception;
}
}
类的构造函数中定义，如下所示：
nmREST我在此XmlNode上测试该功能：
Utils使用此函数调用：
public static XmlNamespaceManager nmREST = new XmlNamespaceManager(new NameTable());
static Utils()
{
nmREST.AddNamespace("d", "http://schemas.microsoft.com/ado/2007/08/dataservices");
nmREST.AddNamespace("m", "http://schemas.microsoft.com/ado/2007/08/dataservices/metadata");
nmREST.AddNamespace("empty", "http://www.w3.org/2005/Atom");
nmREST.AddNamespace("z", "#RowsetSchema");
}
，并且值<entry m:etag=""81"" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom">
<id>Web/Lists(guid'someguid')/Items(1213)</id>
<category term="SP.Data.LibItem" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" />
<link rel="edit" href="Web/Lists(guid'someguid')/Items(1213)" />
<title />
<updated>2019-04-16T06:16:50Z</updated>
<author>
<name />
</author>
<content type="application/xml">
<m:properties>
<d:Id m:type="Edm.Int32" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">1213</d:Id>
<d:FileLeafRef xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">myfile.xlsm</d:FileLeafRef>
<d:FeatureCount m:type="Edm.Double" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">33</d:FeatureCount>
<d:Status xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">Production Ready</d:Status>
<d:CheckoutUserId m:null="true" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" />
<d:EditorId m:type="Edm.Int32" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">25</d:EditorId>
<d:ID m:type="Edm.Int32" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">1213</d:ID>
</m:properties>
</content>
</entry>
已成功检索。
但是，当我在以下XmlNode上对其进行测试时：
getPropertyFromNode_string(thisNode,"ID")
使用函数调用：
1213然后<entry m:etag=""24"" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom">
<id>Web/Lists(guid'someguid')/Items(1422)</id>
<category term="SP.Data.LibItem" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" />
<link rel="edit" href="Web/Lists(guid'someguid')/Items(1422)" />
<link rel="http://schemas.microsoft.com/ado/2007/08/dataservices/related/Station" type="application/atom+xml;type=entry" title="Station" href="Web/Lists(guid'someguid')/Items(1422)/Station">
<m:inline>
<entry>
<id>anotherguid</id>
<category term="SP.Data.DifferentLibItem" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" />
<title />
<updated>2019-04-16T05:58:17Z</updated>
<author>
<name />
</author>
<content type="application/xml">
<m:properties>
<d:FacilityNumber xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">1068</d:FacilityNumber>
</m:properties>
</content>
</entry>
</m:inline>
</link>
<title />
<updated>2019-04-16T05:58:17Z</updated>
<author>
<name />
</author>
<content type="application/xml">
<m:properties>
<d:FileLeafRef xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">thatfilename.xlsm</d:FileLeafRef>
<d:Title m:null="true" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" />
</m:properties>
</content>
</entry>
调用将引发以下消息异常：
getPropertyFromNode_string(thisNode,"FacilityNumber")
我想这意味着XPath表达式无法成功定位SelectSingleNode()元素，因此没有对象可以获取Object reference not set to an instance of an object.
。为什么找不到该元素？第二个节点的XML结构有什么不同，我应该使用什么XPath表达式代替？
答案 0 :(得分：0)
As per Laurent Lequenne's comment on the OP, including the full nesting sequence of child nodes in the XPath expression successfully retrieves the desired child node, as follows:
./empty:link/m:inline/empty:entry/empty:content/m:properties/d: