我在 XslCompiledTransform 中遇到了一个非常相似的异常：
System.Web.HttpUnhandledException (0x80004005): Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at MS.Internal.Xml.Cache.XPathDocumentNavigator.get_NodeType()
at System.Xml.XPath.XPathNavigator.MoveToNonDescendant()
at System.Xml.Xsl.Runtime.DescendantMergeIterator.MoveNext(XPathNavigator input)
at <xsl:template name="SystemPartIncluded">(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime, IList`1 PartNumber, XPathNavigator Description, IList`1 DescriptionOverride, IList`1 Quantity, IList`1 ExtendedPrice, String LabelWhiteSpace)
at <xsl:template name="compiler:generated"> (30)(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime, XPathNavigator {urn:schemas-microsoft-com:xslt-debug}current, XPathNavigator isBundledWithCanvas, XPathNavigator SoftwareExtendedPrice, XPathNavigator SoftwareUnitPrice, IList`1 PixelNet, IList`1 Revision_Date, IList`1 Catalyst)
at <xsl:template name="compiler:generated"> (45)(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime, XPathNavigator {urn:schemas-microsoft-com:xslt-debug}current, XPathNavigator SoftwareUnitPrice, XPathNavigator HardwareExtendedPrice, XPathNavigator HardwareUnitPrice, XPathNavigator PixelNetUnitPrice, XPathNavigator FusionUnitPrice)
at <xsl:template match="Quote">(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime, XPathNavigator {urn:schemas-microsoft-com:xslt-debug}current, Double {urn:schemas-microsoft-com:xslt-debug}position, Double {urn:schemas-microsoft-com:xslt-debug}last)
at <xsl:template match="/">(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime, XPathNavigator {urn:schemas-microsoft-com:xslt-debug}current)
at Root(XmlQueryRuntime {urn:schemas-microsoft-com:xslt-debug}runtime)
at System.Xml.Xsl.XmlILCommand.Execute(Object defaultDocument, XmlResolver dataSources, XsltArgumentList argumentList, XmlWriter writer)
at MyApp.clsXML.XslTransformationToHtml(IQEntities DC, Int32 loggedOnUserID, IXPathNavigable input, String xslStylesheetFilePath, XsltArgumentList xslArgs, String XmlRepositoryVersion) in MyApp\App_Data\Static Classes\xml_routines.cs:line 510
at MyApp.clsQuote.RenderOneQuote(IQEntities DC, Int32 loggedOnUserID, Int32 quoteID, Boolean booPrintFormat, Boolean booDiscount_Prices, Boolean booIs_Super_Administrator, Boolean isHostRep, String strOrganization_Table_Caption, Boolean showBottomLineOnly) in MyApp\App_Data\Static Classes\quote_routines.cs:line 476
at MyApp.Pages.AJAX.BrowseQuotes.RenderSelectedQuote(Int32 quoteID) in MyApp\Pages\AJAX\BrowseQuotes.aspx.cs:line 66
at MyApp.Pages.AJAX.BrowseQuotes.ucQuotePicker1_OnQuoteSelectedEvent(Object sender, Int32 quoteID) in b:\DotNet\IQ\WinMetrics.IQ\Pages\AJAX\BrowseQuotes.aspx.cs:line 56
at System.Web.UI.WebControls.GridView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.HandleError(Exception e)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)
像您一样，我们将 XPathDocument 传递给 Xsl 转换，并且 XPathDocument 正在从分布式缓存中检索。不幸的是，XPathDocument 不可序列化，因此在从分布式缓存中检索后无法使用。我们通过使用 XmlDocument 而不是 XPathDocument 并使用 SerializedXmlDocument 对其进行序列化和反序列化来解决此问题，如下所示：
public static XmlDocument CachedXmlDoc
{
get
{
lock (_locker)
{
// maintain the Part XmlDocument in the distributed cache so that it can be reset from any production instance
SerializedXmlDocument serializedXmlDoc = Reliable.Application[Global.CACHED_XML_DOC] as SerializedXmlDocument;
XmlDocument cachedDoc = (serializedXmlDoc == null) ? null : serializedXmlDoc.XmlDocument;
if (cachedDoc == null)
{
cachedDoc = myController.CreateXmlDoc();
Reliable.Application[Global.CACHED_XML_DOC] = new SerializedXmlDocument(cachedDoc);
}
return cachedDoc;
}
}
set
{
lock (_locker)
{
if (value == null)
{
Reliable.Application[Global.CACHED_XML_DOC] = null;
}
else
{
throw new Exception("Tried to set the cached XmlDocument to something other than null.");
}
}
}
}