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Read an XML documents with a Parent/Child relationship into a class

Mar 16

Written by: Steve Gray
3/16/2011 3:47 PM

The task here is to take an XML document in this form:

And parse it and move it into a class that we can manipulate in VB.

The class structure mirrors the XML document:

Code Snippet
 Public Class Transfer
    Public transferNumber
    Public timestamp As DateTime
    Public transferDetail As List(Of TransferDetail)
    Public test As List(Of String)
 
End Class
 
Public Class TransferDetail
    Public itemguid As Guid
    Public quantity As Double
    Public fromsite As String
    Public tosite As String
End Class
 

Our code loads the XML into an XDocument, and then uses LINQ queries to read it into an instance of the class.

Code Snippet
     Sub example()
        Dim xDoc As XDocument
        Dim eDoc As XElement
        Dim oTransfer As Transfer
        Dim oTransferDetail As TransferDetail
 
        'load an XML document into an xElement type
        eDoc = <transfers>
                   <transfer transferNumber="TSFR001">
                       <timestamp>2011-03-14 11:24:47.077</timestamp>
                       <items>
                           <item>
                               <itemguid>6A639774-5EA9-440C-978B-FDC7DBF71949</itemguid>
                               <quantity>1</quantity>
                               <fromsite>001</fromsite>
                               <tosite>002</tosite>
                           </item>
                           <item>
                               <itemguid>D8FD406F-8CF2-47E6-B09D-E44106153C11</itemguid>
                               <quantity>1</quantity>
                               <fromsite>001</fromsite>
                               <tosite>002</tosite>
                           </item>
                       </items>
                   </transfer>
                   <transfer transferNumber="TSFR002">
                       <timestamp>2011-03-14 11:24:47.077</timestamp>
                       <items>
                           <item>
                               <itemguid>6A639774-5EA9-440C-978B-FDC7DBF71949</itemguid>
                               <quantity>2</quantity>
                               <fromsite>001</fromsite>
                               <tosite>002</tosite>
                           </item>
                           <item>
                               <itemguid>D8FD406F-8CF2-47E6-B09D-E44106153C11</itemguid>
                               <quantity>2</quantity>
                               <fromsite>001</fromsite>
                               <tosite>002</tosite>
                           </item>
                       </items>
                   </transfer>
               </transfers>
 
        'read the xElement into an xDocument. This is the easiest and clearest way to code the example
        xDoc = XDocument.Parse(eDoc.ToString)
 
        'create a collection of xElements
        Dim transferNodes As IEnumerable(Of XElement)
 
        'LINQ query to read the TRANSFERS into our collection
        transferNodes = _
            From el In xDoc.<transfers>.Elements() _
            Select el
 
        'loop through the collection of TRANSFERS
        For Each el As XElement In transferNodes
            'delare a new transfer class
            oTransfer = New Transfer
 
            'initialize the transferDetail Generic.List
            oTransfer.transferDetail = New List(Of TransferDetail)
 
            'assign some of the transfer class properties. Note how we get the transferNumber attribute here
            oTransfer.transferNumber = el.@transferNumber
            oTransfer.timestamp = el.<timestamp>.Value
 
            'the transfer document has childern - items
            'declare a collection of items
            Dim itemNodes As IEnumerable(Of XElement)
 
            'LINQ query to loop through the collection of item elements
            itemNodes = From ie In el.<items>.Elements _
                           Select ie
 
            'loop through the colleciton of ITEMS
            For Each ie As XElement In itemNodes
                'delcare a new transfer detail class
                oTransferDetail = New TransferDetail
 
                'assign some of the class properties
                oTransferDetail.itemguid = New Guid(ie.<itemguid>.Value)
                oTransferDetail.quantity = ie.<quantity>.Value
                oTransferDetail.tosite = ie.<tosite>.Value
                oTransferDetail.fromsite = ie.<fromsite>.Value
 
                'add the new transferdetail class to the parent transfer class
                oTransfer.transferDetail.Add(oTransferDetail)
            Next
        Next
 
 
 
 
    End Sub
End Class
 

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