ComboBox Cast exception

ComboBox Cast exception

Posted by: fsegui on 7 May 2020, 3:57 am EST

• 

  fsegui

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  Posted 7 May 2020, 3:57 am EST

  Hello,
  
  I’m trying the C1ComboBox control. I’m binding datas to the combobox like this:

  cmb.TranslateValue = True
  cmb.ItemsDataSource = comboData
  cmb.ItemsDisplayMember = "DisplayString"
  cmb.ItemsValueMember = "ItemData"
  
  Dim comboData As New BindingSource
  
  comboData.Add(new ComboItem("string1",1)
  comboData.Add(new ComboItem("string2",2)
  ...
  

  When I try to iterate through all items and convert them as ComboItem, I’ve got an InvalidCastException: impossible to convert String to ComboItem:

  For i = 0 To cmb.Items.Count - 1
  	If CType(cmb.Items.Item(i), ComboItem).ItemData = Itemdata Then
  		cmb.SelectedIndex = i
  		Exit Sub
  	End If
  Next i
  

  ComboItem class

  Public Class ComboItem
      Public Property DisplayString As String
      Public Property ItemData As Object
      Public Sub New(displayString As String, Optional itemData As Object = Nothing)
          Me.DisplayString = displayString
          Me.ItemData = itemData
      End Sub
  End Class
  

  How can I get the object and not just the string?

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  prabhat.sharma

  

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  Posted 8 May 2020, 4:27 am EST

  Hi Florent,

  The Item property of C1ComboBox returns the ItemsValueMember at associated with particular indexes.

  To get the ComboItem object at a particular index, you need to iterate through the BindingSource object that is assigned as the DataSource of the C1ComboBox as given in code snippet below:

  For i = 0 To comboData.Count - 1
              If CType(comboData.Item(i), ComboItem).ItemData = ItemData Then
                  C1ComboBox1.SelectedIndex = i
              End If
          Next
  

  Regards,
  
  Prabhat Sharma.

• 

  fsegui

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  Posted 8 May 2020, 7:17 am EST

  Hi,

  Thanks for the details. Works fine like this. Does the text property always returns the itemsdisplaymember ?

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  prabhat.sharma

  

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  Posted 11 May 2020, 12:08 am EST

  Hi Florent,

  The Text property of the ComboBox returns the currently selected display member that is shown in the ComboBox editor area.

  Regards,
  
  Prabhat Sharma.

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  fsegui

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  Posted 11 May 2020, 9:14 am EST

  Thanks, that works.