Problem with combobox

Problem with combobox

• wsauer

  couple of things:
  
  1) seems that with every EditingControlShowing event an Additional handler is added and they build up.  Shouldn't the tail end of cbo_Validating have:
  cbo.Validating -= new CancelEventHandler(cbo_Validating);
  added so that cbo_Validating only executes once per EditingControlShowing event
  when i add a trace to check the number of times cbo_Validating fires the number keeps getting higher ... maybe i implemented it different than you...
  
  2) intermittantly I'm still getting the data error.  not every time, but enough that I notice. And when I'm getting the error it seems that the data_error event is raised before the cbo.Validating event.  I'm starting to think about adding the item in .cellValidating as it executes before .DataError event
  
  what do you think
  
  /gabe

  
  

• Faris Mlaeb

  Thanks  again.
  

• Work2

  The DataGridView raises a DataError when the value is not in the ComboBox's list.  To display the value, you must add the value to the ComboBox.  The other option is to create your own combobox column.
  
  There must not be a foreign key relationship between your two tables, or else you wouldn't be having this problem.  How were you going to have users enter data not in the combobox   It seems like you are looking for the ComboBoxStyle.DropDownList behaviour in DataGridViewComboBoxColumn.   What follows is an example of how to accomplish this.
  
  The ComboBox used by the DataGridViewComboBoxColumn has a DropDownStyle property set to ComboBoxStyle.DropDownList, but DataGridViewComboBoxColumn does not expose this property, so out-of-box there is no way to type text into a combobox column.  You can change this by handling the EditingControlShowing event, and setting the DropDownStyle:
  
  

  void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e) { if (e.Control.GetType() == typeof(DataGridViewComboBoxEditingControl)) { DataGridViewComboBoxEditingControl cbo = e.Control as DataGridViewComboBoxEditingControl; cbo.DropDownStyle = ComboBoxStyle.DropDown; cbo.Validating += new CancelEventHandler(cbo_Validating); } }

  
  
  In this example, all ComboBox columns will have the DropDownStyle property set to DropDown.  In addition, handle validating to add user-typed items to the list.
  

  
  

  void cbo_Validating(object sender, CancelEventArgs e) { DataGridViewComboBoxEditingControl cbo = sender as DataGridViewComboBoxEditingControl; DataGridView grid = cbo.EditingControlDataGridView; object value = cbo.Text; // Add value to list if not there if (cbo.Items.IndexOf(value) == -1) { DataGridViewComboBoxColumn cboCol = grid.Columns[grid.CurrentCell.ColumnIndex] as DataGridViewComboBoxColumn; // Must add to both the current combobox as well as the template, to avoid duplicate entries... cbo.Items.Add(value); cboCol.Items.Add(value); grid.CurrentCell.Value = value; } }

  
  

• Dusty21269

  Hi Durstin,
                  In your post you said:
  >    "The other option is to create your own combobox column."
  
  Any chance you could give me a quick run through on how to do this I presume it would mean inheriting from DataGridViewComboBoxColumn which in turn would mean inheriting from DataGridViewComboBoxCell in order to get access to the editing control. What method in DataGridViewComboBoxCell would I have to override in order to ensure any data which is not in the combo box's datasource is still drawn
  
  I hope this makes sense!, if not I will try and explain it better.
  
  Thanks,
  Cathal.
  
  

• Niky

  My reply is to the origianl post and also that which explians the cause of the error as a value not in the list of items in the combobox column.
  
  First I have the same problem as originally stated. I'm convinced that the combobox column property DataPropertyName is not set to something valid - in fact the DataSource for the box seems to supply info from only one table - it is after set to a single DataTable object.
  
  As for values not being in the dropdownlist, I agree its a problem, but in a parent/chaild table, the re will be FK's in the parent table that are NULL. This should not cause an error. It certainly doesn't in the normal Combobox control. I have both on a single form and the normal combobox works fine from the same two tables all because it can be bound to both tables through data bindings. The combobox column doesn't have that ability.
  
  

• Oso Hada

  A thought for you Raju.
  
  Check to see if the DisplayStyle for the column is DropDownButton
  and the DisplayStyleForCurrentCellOnly is false.

  
  

• tehlike

  hi,
  i have the same situation like in the first post. I tryed to bound the combobox via
  smart tag and manually in the formattingcell event. I bounded it to a dataset,datatable,dataview,arraylist. it always raises an dataerror.(wrong value)
  
  please give me an example how to bind the box to one column of my datatable.
  
  thanx
  

• Kaishain

  Hi,
  
  I have copied this code but I get this error:
  
  "No se puede modificar la coleccion Items cuando esta establecida la propiedad DataSource."
  
  in
  
  cmb.Items.Add(value)
  
  I fill the comboboxcolumn from a database and I belive that this is the problem. How can I solve it
  
  
  Thanks
  

• melcom

  http://www.windowsforms.net/Samples/Go%20To%20Market/DataGridView/DataGridView%20FAQ.doc
  
  seemed to answer the vast majority of the problems i had.  if that doesn't lead you to the solution repost and i'll put together a sample
  
  gabe
  

• JDL440

  First, I can't read much else but English, so I don't understand your question.
  
  Second...In many other posts of mine and others' its become clear that the DataGridView Combobox control is incomplete. It needs the capability to bind to two tables in a dataset. The normal combobox control has this ability through its databinding collection. The current DGV Combobox gives all of us roughly the same errors for very much the same reasons.
  
  

• Keyboard_Cowboy

  Hi mafc,

  I'm guessing your problem is you have bound the DataSource property. Instead, set DataSource to "none" and fill the combo's Items collection in the Form_Load event. Here is sample code from my previous post in this thread to do this:

  Me.MyTableAdapter.Fill(Me.MyDataSet.MyList)

  MyDataGridViewComboBox.Items.Clear() 'This probably isn't necessary if done in the Load.

  'fill combobox

  Dim row As DataRow

  For Each row In Me.MyDataSet.MyList

  MyDataGridViewComboBox.Items.Add(row.Item(0))

  Next

  Hope that helps!

  
  

• H. Feijt

  
  Yes this is my problem, but I don't know how to use your example in my code. My code is this :
  
  dim column_combo As DataGridViewComboBoxColumn = New DataGridViewComboBoxColumn()
  .....
  
  SQL = "select CANT_NOMBRE from T_CANTIDADES"
  
  Dim dbDataSet_Cantidades As New Data.DataSet
  Dim tabla_Cantidades As New DataTable
  
  Try
  dbDataSet_Cantidades.Clear()
  
  dbDataAdapter = New FirebirdSql.Data.FirebirdClient.FbDataAdapter(SQL, FbConnection)
  dbDataAdapter.Fill(dbDataSet_Cantidades)
  
  tabla_Cantidades = dbDataSet_Cantidades.Tables(0)
  
  Catch ex As Exception ' catches any error
  
  MsgBox("Ha fallado al rellenar la columna cantidad")
  Finally
  End Try
  
  With column_combo
  
  .DataSource = tabla_Cantidades
  .ValueMember = "CANT_NOMBRE"
  .DisplayMember = .ValueMember
  .......
  .DataPropertyName = "CANTIDAD"
  .HeaderText = "CANTIDAD"
  .HeaderCell.Value = "CANTIDAD"
  
  End With
  
  Me.DGV_Recetas.Columns.Add(column_combo)
  
  Can I incorporate your code in the mine.
  
  Thanks
  
  
  
  

• PCHOU

  hi,

  in my program i have used one combobox . when i desing this combobox that time this is ok but now this combo is look transperent how it happened when i click on combo then it look like combo with item list but at first time when programe started it will like textbox with out border. i put another combo but it is like old one . this effect is show in this project only if i working another project then combo is like good. if you say then i send you this splash screen with this combo.

  please give me solutional for this problem.

  raju

  
  
  

• Stephie

  I pieced together helpful code from this thread and other sources, translated them to VB.NET and enhanced it to work for ALL comboboxes in the DataGridView. These routines should make the comboboxes editable, i.e., allow users to enter new values. (I also included commented out code that limits it to a specific combobox.)

  VB programmers should be able to copy and paste this code and just change "MyDataGridView" to the name of their DataGridView. (If you uncomment the code that uses "MyDataGridViewComboBox", you will need to change that to the name of your combobox.)

  This assumes that the combobox list is not bound to a datasource, but filled in the Form_Load event. This needs to be done for each combobox in the DataGridView. Here is a sample:

  'TODO: This line of code loads data into the 'MyDataSet.MyList' table. You can move, or remove it, as needed.

  Me.MyTableAdapter.Fill(Me.MyDataSet.MyList)

  MyDataGridViewComboBox.Items.Clear() 'This probably isn't necessary if done in the Load.

  'fill combobox

  Dim row As DataRow

  For Each row In Me.MyDataSet.MyList

  MyDataGridViewComboBox.Items.Add(row.Item(0))

  Next

  VB programmers should be able to copy and paste the rest of this code and just change "MyDataGridView" to the name of their DataGridView. (If you uncomment the code that uses "MyDataGridViewComboBox", you will need to change that to the name of your combobox.)

  Private Sub MyDataGridView_EditingControlShowing(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles MyDataGridView.EditingControlShowing

  'Allow user to enter new values for ALL DataGridViewComboBox controls in the DataGridView

  If (TypeOf e.Control Is DataGridViewComboBoxEditingControl) Then

  Dim cmb As DataGridViewComboBoxEditingControl = CType(e.Control, DataGridViewComboBoxEditingControl)

  If Not cmb Is Nothing Then

  cmb.DropDownStyle = ComboBoxStyle.DropDown

  End If

  End If

  'Following Works for a specific combobox ///////////

  'If MyDataGridView.CurrentCellAddress.X = MyDataGridViewComboBox.DisplayIndex Then

  ' Dim cmb As ComboBox = CType(e.Control, ComboBox)

  ' If Not cmb Is Nothing Then

  ' cmb.DropDownStyle = ComboBoxStyle.DropDown

  ' End If

  'End If

  End Sub

  Private Sub MyDataGridView_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles MyDataGridView.CellValidating

  'Allow user to enter new values for all DataGridViewComboBox controls in the DataGridView

  If (TypeOf CType(sender, DataGridView).EditingControl Is DataGridViewComboBoxEditingControl) Then

  Dim cmb As DataGridViewComboBoxEditingControl = CType(CType(sender, DataGridView).EditingControl, DataGridViewComboBoxEditingControl)

  If Not cmb Is Nothing Then

  Dim grid As DataGridView = cmb.EditingControlDataGridView

  Dim value As Object = cmb.Text

  '// Add value to list if not there

  If cmb.Items.IndexOf(value) = -1 Then

  '// Must add to both the current combobox as well as the template, to avoid duplicate entries...

  cmb.Items.Add(value)

  Dim cmbCol As DataGridViewComboBoxColumn = CType(grid.Columns(grid.CurrentCell.ColumnIndex), DataGridViewComboBoxColumn)

  If Not cmbCol Is Nothing Then

  cmbCol.Items.Add(value)

  End If

  End If

  grid.CurrentCell.Value = value

  End If

  End If

  ''Following Works for a specific combobox ///////////

  'If e.ColumnIndex = MyDataGridView.Columns("DataGridViewComboBoxColSize").Index Then 'CType(sender, DataGridView).CurrentCell.ColumnIndex

  ' 'Dim cmb As ComboBox = CType(e.Control, ComboBox)

  ' Dim cmb As DataGridViewComboBoxEditingControl = CType(CType(sender, DataGridView).EditingControl, DataGridViewComboBoxEditingControl)

  ' If Not cmb Is Nothing Then

  ' Dim grid As DataGridView = cmb.EditingControlDataGridView

  ' Dim value As Object = cmb.Text

  ' '// Add value to list if not there

  ' If cmb.Items.IndexOf(value) = -1 Then

  ' '// Must add to both the current combobox as well as the template, to avoid duplicate entries...

  ' cmb.Items.Add(value)

  ' Dim cmbCol As DataGridViewComboBoxColumn = CType(grid.Columns(grid.CurrentCell.ColumnIndex), DataGridViewComboBoxColumn)

  ' If Not cmbCol Is Nothing Then

  ' cmbCol.Items.Add(value)

  ' End If

  ' grid.CurrentCell.Value = value

  ' End If

  ' End If

  'End If

  ''//////////

  End Sub

  Private Sub MyDataGridView_DataError(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles MyDataGridView.DataError

  'I don't know if this is really necessary.

  If e.Exception.Message = "DataGridViewComboBoxCell value is not valid." Then

  e.Cancel = True

  End If

  End Sub

  
  
• Problem with combobox