BUG: Data Not Sorted When You Use Namespace Prefix in String Passed to XPathExpression.AddSort

Steps to Reproduce the Behavior

1. Use the following code to create and save an XML document named "Testsort.xml" in the root folder of your hard disk:

   <?xml version="1.0" encoding="utf-8" ?> 
   <type xmlns:test='urn:Test'>
      <elements>
         <element name='element_1' test:order='1'>1</element>
         <element name='element_6' test:order='6'>6</element>
         <element name='element_7' test:order='5'>5</element>
         <element name='element_8' test:order='4'>4</element>
         <element name='element_9' test:order='3'>3</element>
      </elements>
   </type>
   					

2. Use Microsoft Visual Studio .NET to create a new Microsoft Visual Basic .NET Windows Application project.
3. Import the System.Xml and System.Xml.XPath namespaces by adding the following statements at the top of the Form1.vb class module:

   Imports System.Xml
   Imports System.Xml.XPath
   					

4. Drag a Button control from the toolbox to the designer surface of Form1.vb.
5. Paste the following code in the Click event procedure of the command button to sort the data in Testsort.xml on the order attribute of the <element> element in descending order. Note that the order attribute is prefixed with a custom namespace prefix (test) and that a string is used in the call to the AddSort method to specify the sort expression.

   Dim doc As New XPathDocument("C:\Testsort.xml")
   Dim nav As XPathNavigator = doc.CreateNavigator()
   
   Dim nsmgr As XmlNamespaceManager = New XmlNamespaceManager(nav.NameTable)
   nsmgr.AddNamespace("test", "urn:Test")
   
   Dim expr As XPathExpression
   expr = nav.Compile("/type/elements/element")
   expr.SetContext(nsmgr)
   
   'Dim expr2 As XPathExpression = nav.Compile("@test:order")
   'expr2.SetContext(nsmgr)
   
   expr.AddSort("@test:order", XmlSortOrder.Descending, XmlCaseOrder.None, "", XmlDataType.Number)
   expr.SetContext(nsmgr)
   
   Dim iterator As XPathNodeIterator = nav.Select(expr)
   Do While iterator.MoveNext()
         System.Diagnostics.Debug.WriteLine(iterator.Current.Value)
   Loop
   					

6. Save and then run the project. Click the button when the form is displayed. On observing the result generated to the Output window, notice that the data was not sorted.
7. Uncomment the two lines of code that create an instance of the second XPathExpression object (expr2) and execute its SetContext method to associate it with the XmlNamespaceManager.
8. Replace the call to the AddSort method of the first XPathExpression object (expr) with the following code:

   expr.AddSort(expr2, XmlSortOrder.Descending, XmlCaseOrder.None, "", XmlDataType.Number)
   						

   You can also remove the expr.SetContext statement that follows the call to the AddSort method.
9. Save and then run the project. Click the button when the form is displayed. Notice that the data is sorted in descending order as required.

Back to the top