How to sort a collection of XElements by their XElement name

I have the following XML; I read it as a collection of XElements:

<rql:select rdf:parseType=""Resource"" xmlns:rdf=""http://www.w3.org/1999/02/22-rdf-syntax-ns#"" xmlns:rql=""http://www.ibm.com/xmlns/rdm/rql/"">
  <rdf:_22 rdf:parseType=""Resource"">
    <rql:field rdf:resource=""https://myserver.io:9443/rm/types/AD_f2cj0RV6EemaLdP_3R0zIQ"" />
    <rql:object>R1</rql:object>
  </rdf:_22>
  <rdf:_14 rdf:parseType=""Resource"">
    <rql:field rdf:resource=""https://myserver.io:9443/rm/types/AD_tEUSIXs4EeeSaIGgVG63HA"" />
    <rql:object>R1</rql:object>
  </rdf:_14>
  <rdf:_16 rdf:parseType=""Resource"">
    <rql:field rdf:resource=""https://myserver.io:9443/rm/types/AD_UOY7kF4EEe6HPajZS8U1aA"" />
    <rql:object>R1</rql:object>
  </rdf:_16>
</rql:select>

I would like to sort the collection using the element names. In this case, the element name would be the number represented by an underscore.

I have already tried to access this name, but only succeeded by looping through the individual elements. Is it possible to order the collection directly in one command?

Solution

I would define helper method to extract suffix to use in sorting the collection:

Private Function GetNumericSuffix(localName As String) As Integer
    Dim parts() As String = localName.Split("_"c)
    Dim number As Integer
    If parts.Length > 1 AndAlso Integer.TryParse(parts(1), number) Then
        Return number
    Else
        Return Integer.MaxValue
    End If
End Function

And the you can use like below:

Public Sub Main()
    Dim xml As String = "
<rql:select rdf:parseType='Resource' xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#' xmlns:rql='http://www.ibm.com/xmlns/rdm/rql/'>
  <rdf:_22 rdf:parseType='Resource'>
    <rql:field rdf:resource='https://myserver.io:9443/rm/types/AD_f2cj0RV6EemaLdP_3R0zIQ' />
    <rql:object>R1</rql:object>
  </rdf:_22>
  <rdf:_14 rdf:parseType='Resource'>
    <rql:field rdf:resource='https://myserver.io:9443/rm/types/AD_tEUSIXs4EeeSaIGgVG63HA' />
    <rql:object>R1</rql:object>
  </rdf:_14>
  <rdf:_16 rdf:parseType='Resource'>
    <rql:field rdf:resource='https://myserver.io:9443/rm/types/AD_UOY7kF4EEe6HPajZS8U1aA' />
    <rql:object>R1</rql:object>
  </rdf:_16>
</rql:select>"

    Dim doc As XElement = XElement.Parse(xml)

    ' Sort child elements using a helper function to extract the numeric suffix
    Dim sortedElements As List(Of XElement) = doc.Elements() _
        .OrderBy(Function(el) GetNumericSuffix(el.Name.LocalName)) _
        .ToList()

    For Each el As XElement In sortedElements
        Console.WriteLine(el)
    Next
End Sub