How to update text in a textbox that is created dynamically in wpf

Question

In WPF, I created several TextBoxes dynamically, then later, I go find all the child objects of the Canvas I created them in. As I search, I can get the name of the textbox, but how do I change the text in the textbox?

I have tried:

// oText is the visual object I found when searching for the textbox
oText.Text = "Software" // doesnt work.
oText.SetValue(control.Text) // doesnt work, because there is no .text property

Even through I can debug it, and hover over the oText object, and scroll down and find that Text property is set to "Software", but I can't read it like I can with

oText.GetValue(control.width)

How do we read the text value in WPF of this dynamically created textbox?

Here is the code:

I create a canvas in XAML:

 <Canvas x:Name="Can1" Height="700" Width="874">

        </Canvas>

Then, I make the textboxes and put them on the canvas...

 For i As Integer = 0 To VisualTreeHelper.GetChildrenCount(Can1) - 1
        ' Retrieve child visual at specified index value.
        Dim childVisual As Visual = CType(VisualTreeHelper.GetChild(Can1, i), Visual)
        ' Return the offset vector for the TextBlock object.
        Dim vector As Vector = VisualTreeHelper.GetOffset(childVisual)
        ' Convert the vector to a point value.
        Dim currentPoint As New Point(VisualOffset.X, VisualOffset.Y)
        x = Canvas.GetLeft(childVisual)
        y = Canvas.GetTop(childVisual)

        A = childVisual.GetValue(Control.ActualHeightProperty)
        B = childVisual.GetValue(Control.ActualWidthProperty)     

        Dim myTextbox As New TextBox
        Dim c As Int16
        myTextbox.Width = B
        myTextbox.Text = "Software"
        myTextbox.Name = "TextB" & i.ToString
        Can1.Children.Add(myTextbox)
        Canvas.SetTop(myTextbox, y + A)
        Canvas.SetLeft(myTextbox, x)
        Canvas.SetZIndex(myTextbox, 0)
next i

Then, I use a button on the main window to call GetData...

Private Sub GetData(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
    Dim iCount As Int16
    Dim oText As Visual
    Dim sTemp As String
    Dim cs = My.Settings.ConnectionString
    Dim oConn = New SqlConnection(cs)
    Dim cmd As New SqlCommand()
    Text1.text = ""
    cmd.Connection = oConn
    Try
        oConn.Open()
        cmd.CommandText = "select top 5 finumber from fiheading "
        Dim myReader As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection)
        While myReader.Read()
            iCount += 1
            oText = FindChild(Can1, "TextB" & iCount.ToString)
            'sTemp = oText.GetValue(Control.NameProperty)
            'oText.text = (myReader.GetString(0))
            'oText.SetValue(Control.text)

        End While
        myReader.Close()
    Catch ex As Exception
        MsgBox(ex.Message)

    End Try


    Try
        oConn.Close()
    Catch ex As Exception
        MsgBox(ex.Message)

    End Try


End Sub

Is oText of type TextBox? Or is it something else generic such as FrameworkElement or object? — Rachel
Ok, I put some of my code in the window above. I create the textbox and then go try to find them when a button is pressed. I am getting data from the SQL database, and as you can see I have several commented out lines where I was trying different things. So the object is a visual that I found as a child on the canvas. I can hover over it in debug and click on the +'s and expand the properties to see there is a text property = "Software", but I dont know how to read it or write to it. — SDanks

Rachel Rachel · Accepted Answer · 2012-06-28T19:55:30

oText is defined as a Visual, which does not have a Text property

Change it to a TextBox and cast the result of FindChild to a TextBox and it should work fine

Dim oText As TextBox
...

oText = CType(FindChild(Can1, "TextB" & iCount.ToString), TextBox)

How to update text in a textbox that is created dynamically in wpf

1 Answers