[RESOLVED] VB.NET 2008 and XML

[Darraca]

Hi I have an XML document that is similar to the following:

<?xml version="1.0" encoding="utf-8"?>
<Root>
<Items>
<Item ItemID="1">
TEST1
</Item>
<Item ItemID="2">
TEST2
</Item>
<Item ItemID="3">
TEST3
</Item>
</Items>
</Root>

What I would like to do is have a text box and a button on a form where the user can type in say 'TEST4' and have this added to <Items> in the xml. I would also like to check if the text typed in to the text box already exists in <Items> before it is added. Is there anyway to do this?

Kind Regards

[proneal]

Hi OP, the answer to your question is Yes and one of the objects you could use to read the xml is the XmlReader. As you would expect, there is an XmlTextWriter object that can write the new values.

Examples online are in abundance to the degree that some have posted to leave your XmlTextWriter at home since there is already too much use of it as it is...

[kareninstructor]

The following example is a partially controlled demo in that instead of a TextBox a ComboBox is used with values inline with what you asked for. If this works for you than simply replace the ComboBox for a TextBox.

Form
1 DataGridView with two columns created in the IDE
Column 1 DataProperty = Identifier
Column 2 DataProperty = Value

1 ComboBox, 1 Button

Feel free to adjust the new items indent level as per your liking.

Public Class Form1
    Private Document As New XDocument
    Private FileName As String = IO.Path.Combine(Application.StartupPath, "Document.xml")
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        DataGridView1.AutoGenerateColumns = False
        Document = XDocument.Load(FileName)
        DataGridView1.DataSource = _
            ( _
                From T In Document...<Item> _
                Select New With _
                       {   .Identifier = T.@ItemID, _
                           .Value = T.Value.Trim _
                       } _
            ).ToDataTable
        ComboBox1.DropDownStyle = ComboBoxStyle.DropDownList
        ComboBox1.DataSource = (From T In Enumerable.Range(1, 20) Select "TEST" & T.ToString).ToList
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim Result = (From T In Document...<Item> Where T.Value.Trim = ComboBox1.Text).FirstOrDefault
        If Result IsNot Nothing Then
            MessageBox.Show("Item in file already")
        Else
            Dim NextId As Integer = (From T In Document...<Item> Select CInt(T.@ItemID)).Max + 1
            Dim NewItem = <Item ItemID=<%= NextId %>><%= ComboBox1.Text %></Item>
            Document...<Items>(0).Add(NewItem)
            Document.Save(FileName)
            CType(DataGridView1.DataSource, DataTable).Rows.Add(New Object() {NextId, ComboBox1.Text})
        End If
    End Sub
End Class

Code Module for a language extension method (cannot be in a form)

<System.Diagnostics.DebuggerStepThrough()> _
<System.Runtime.CompilerServices.Extension()> _
Public Function ToDataTable(Of T)(ByVal value As IEnumerable(Of T)) As DataTable

    Dim returnTable As New DataTable
    Dim firstRecord = value.First

    For Each pi In firstRecord.GetType.GetProperties
        returnTable.Columns.Add(pi.Name, pi.GetValue(firstRecord, Nothing).GetType)
    Next

    For Each result In value
        Dim nr = returnTable.NewRow
        For Each pi In result.GetType.GetProperties
            nr(pi.Name) = pi.GetValue(result, Nothing)
        Next
        returnTable.Rows.Add(nr)
    Next
    Return returnTable
End Function

XML document named Document.xml to reside in the same folder as the executable.

<?xml version="1.0" encoding="utf-8" ?>
<Root>
  <Items>
    <Item ItemID="1">
      TEST1
    </Item>
    <Item ItemID="2">
      TEST2
    </Item>
    <Item ItemID="3">
      TEST3
    </Item>
  </Items>
</Root>

[Darraca]

Thanks, I've managed to get this working now.