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

<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>

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

The class structure mirrors the XML document:

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

This code sample will show you how to take an XML document and parse it into VB elements (in this example I use a class)

First create the class:

This code will take the XML document shown are read it into the class. You’d want a Generic Collection of this class to get all the items, I’m going for simplicity here as much as possible

I’m… just not a big fan of LINQ. It’s hard to work with, the syntax is obscure and it’s hard to find documentation for. I’m not sure if it’s something that will be around in the future.

Anyway, I have this task that reoccurs every so often – given a DataTable, I need to group the table by one (or more) of the fields and do something with the group. Often I need to iterate through the lines in the table that match a group.

Note that the first query returns one field, so when you reference that field in ‘salesQueryItem’, you only need strTo = salesQueryItem. In the second loop there is more than one field in the select, so they’re itemized.

I frequently have to read from XML files, the general format of them is something like this:

<eConnect xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <POPReceivingsType>
    <taUpdateCreateVendorRcd>
    </taUpdateCreateVendorRcd>
    <taCreateVendorAddress>
    </taCreateVendorAddress>
    <taPopRcptLineInsert_Items>
      <taPopRcptLineInsert>
        <PONUMBER>PO08/00012</PONUMBER>
        <LOCNCODE>VA-PIEDMONTB</LOCNCODE>
      </taPopRcptLineInsert>
      <taPopRcptLineInsert>
        <PONUMBER>PO08/00012</PONUMBER>
        <LOCNCODE>VA-PIEDMONTA</LOCNCODE>
      </taPopRcptLineInsert>
    </taPopRcptLineInsert_Items>
    <taPopRcptHdrInsert>
      <POPRCTNM>RC08/00028</POPRCTNM>
      <POPTYPE>1</POPTYPE>
    </taPopRcptHdrInsert>
  </POPReceivingsType>
</eConnect>

Here’s a simple piece of code that will read the first <taPopRcptLineInsert> node and 

give me the element contained in it. 

In earlier .NET Framework versions I had to set references and include ‘IMPORTS’ 

directives, 4.0 is not requiring that. 

Public Class Form2
 
    Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _

Handles MyBase.Load
        test()
    End Sub
 
    Private Sub test()
        Dim strPOnumber As String
        Dim strLOCNCODE As String
 
        Dim doc As System.Xml.Linq.XDocument = _

XDocument.Load(Application.StartupPath & "\xmlfile1.xml")
 
        Dim query = _
            From c In doc.<eConnect>.<POPReceivingsType>.<taPopRcptLineInsert_Items> _
            Select c.Nodes.First
 
        For Each g As XElement In query
            strPOnumber = g.<PONUMBER>(0).Value
            strLOCNCODE = g.<LOCNCODE>(0).Value
        Next
 
    End Sub
End Class

Recently I had a project where I needed to have a small configuration file/table that a user could maintain, possibly add records to if needed. The overhead to put that in SQL was a little too much – I’d need to write forms for the maintenance, handle security… it would take a bit to do all that.

Instead, it seemed easier to write an XML file to handle the task and to allow the user FTP access to the web site. So, given an XML file, how do I get access to all the fields in one ‘record’? LinqToXML to the rescue.

First, create a class to represent the record

Public Class eCard
    Public cardID As Int16
    Public image As String
    Public imageThumb As String
    Public subject As String
    Public label As String
End Class

Then, here is code to read the XML file and populate the class. This is a ASP DataList ItemCommand method, the DataList as the ‘cardID’ in the CommandArgument.

Imports System.Data
Imports System.Xml.Linq
Imports System.Linq
Imports System.Xml

    Protected Sub lstCards_ItemCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataListCommandEventArgs) Handles lstCards.ItemCommand
        Dim doc = XDocument.Load(Server.MapPath("/eCards/eCard.xml"))
        Dim cardID As Int16 = e.CommandArgument
        Dim query = _
            From c In doc.<cards>.<card> _
            Where c.<cardID>.Value = cardID _
            Select c
        Dim eCard As New eCard
        For Each g In query
            eCard.cardID = cardID
            eCard.image = g.<image>(0).Value
            eCard.imageThumb = g.<imageThumb>(0).Value
            eCard.subject = g.<subject>(0).Value
            eCard.label = g.<label>(0).Value
        Next
        Session("eCard") = eCard
        Response.Redirect("eCards2.aspx")
    End Sub

In a recent project, I needed to sum data in a web page grid and process it on postback.

I could get it into at datatable easily enough, but getting it grouped and summed was stumping me.

Our columns are ITEMNMBR, QUANTITY, LOTNUMBER, DEX_ROW_ID. We’ll group on ITEMNMBR and DEX_ROW_ID. We’ll sum on QUANTITY

So, the data might be:
ITEM1, 5, LOT A, 1001
ITEM1, 6, LOT B, 1001
ITEM2, 1, <NULL>, 1002
ITEM3, 2, <NULL>,1003

Lines 1 and 2 above have the same item number and row id, but 2 different lot numbers.

The ‘groupRow’ item in the code below holds a set of rows of the underlying group. In the second section of code we loop through that object. Note that there are two quantity results, the group quantity (11) and the line quantity (5,6)

Here’s the solution. It uses LINQ, so add a reference to SYSTEM.LINQ at the top of the page. Note the use of a system function to do the summing; it’s declared in the second line

Dim oDT As DataTable = gridToDataTable(Me.Grid1)

Dim aggregateSum As System.Func(Of DataRow, Integer) = AddressOf GetSum

Dim data = From c In oDT.AsEnumerable() _

           Group c By itemGroup = c.Field(Of String)("itemnmbr"), _

                dexGroup = c.Field(Of Int32)("dex_row_id") Into Group _

           Select groupRow = Group, _

                itemGroup = itemGroup, _

                quantity = Group.Sum(aggregateSum), _

                dexGroup = dexGroup

For Each g In data

    strItemnmbr = g.itemGroup

    dblItemSellingQtyReceived = g.quantity

    intDex_row_id = g.dexGroup

    For Each n In g.groupRow

        strSerltnum = n("serltnum")

        dblLotSellingQtyReceived = n("quantity")

    Next

Next

The function:

Public Function GetSum(ByVal datarow As DataRow) As Integer

    Return Integer.Parse(datarow("quantity").ToString())

End Function