NullText for C1Treeview Node

NullText for C1Treeview Node

Posted by: kbj on 22 February 2023, 4:52 am EST

• 

  kbj

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  Posted 22 February 2023, 4:52 am EST

  Hi Folks,
  
  With an AllowEdit c1Treeview, is there a way to have a node by node Equivalent to C1TextBox’s NullText. The treeview nodes contain an object with a property named “title”; the treeview DisplayFieldName property is “title”. If the object’s title is nothing, I’d like the node display a default title comprised of some other property of the object.
  
  An example would be:
  
  If the object is a fiscal year that has an ending date property of December 31, 2023, if the user leaves the title property blank, the node would display “FYE December 31, 2023”. On entering edit mode, the editor should be blank. If the user exits the edit mode, and the value is still blank, the default value should be displayed.
  
  Any ideas?
  
  Thanks,
  
  Kingman

• 

  nitin.sharma

  

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  Posted 22 February 2023, 6:32 pm EST

  Hi,

  You can override ToString() method and set a Default value to the title if it’s null or empty.

          Public Overrides Function ToString() As String
              If Title = "" Or Title = Nothing Then
                  Title = "Default Value"
                  Return Title
              End If
              Return MyBase.ToString()
          End Function

  Please refer the attached sample for the same:TreeViewDemo.zip

  Best Regards,
  
  Nitin

• 

  kbj

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  Posted 23 February 2023, 1:07 am EST

  Hi Nitin,
  
  As you noticed, simply overriding the ToString Function, or as I did it:

      Public Property title As String
          Get
              If String.IsNullOrEmpty(_title) Then
                  Return "{Default Value}"
              Else
                  Return _title
              End If
          End Get
          Set(value As String)
              If Not Equals(value, _title) Then
                  _title = value
                  NotifyPropertyChanged()
              End If
          End Set
      End Property

  doesn’t reset the displayed value to the default after editing and replacing the value to “”. You get around this by resetting the DataSource, which is awkward and you will notice collapses all the expanded branches after editing amongst other problems.
  
  The problem is that the node displayed value is now blank and not the ToString value or, in my case, the DisplayFieldName of the object.
  
  Reloading the node doesn’t work:

          Private editItem As ClassData
          Private Sub CellBeginEdit(sender As Object, e As C1TreeViewNodeCellCancelEventArgs)
              editItem = CType(e.Node.GetValue, ClassData)
          End Sub
          Private Sub CellEndEdit(sender As Object, e As C1TreeViewNodeCellEventArgs)
              e.Node.SetValue(editItem)
          End Sub

  I wish there was a way to “Refresh” the node after the edit.

• 

  avnish.kumar

  

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  Posted 26 February 2023, 4:50 pm EST

  Hi,

  We could see the issues you mentioned. As a workaround, you can use the way you mentioned i.e. returning the default value from the property if the value is empty or null.
  
  Then in the CellEndEdit’s event handler you can call the EndUpdate method of the TreeView. Please refer to the sample attached and let us know if you face any problems.

  Regards.

  TreeViewDemo_mod.zip