DataGridView单元格ComboBox选值后无法替换为TextBox的问题求助

Hey there! Let's fix that issue where your DataGridView ComboBox isn't switching to a TextBox after selection.

First, let's break down why your current code isn't working: you're trying to assign a DataGridViewTextBoxCell to DataGridView1.CurrentCell.Value, but the Value property is for storing the cell's data—not the cell object itself. That's why you don't see any visual change; you're just setting a value to an object instead of replacing the cell type.

Here's the step-by-step solution to get this working:

1. Correctly Bind the ComboBox Selection Event #

First, make sure you're setting up the ComboBox's SelectedIndexChanged event properly in the EditingControlShowing event (this is where you typically customize the editing control for DataGridView cells):

Private Sub DataGridView1_EditingControlShowing(sender As Object, e As DataGridViewEditingControlShowingEventArgs) Handles DataGridView1.EditingControlShowing
    If e.ColumnIndex >= 0 And e.RowIndex >= 0 Then
        Dim comboBox As ComboBox = TryCast(e.Control, ComboBox)
        If comboBox IsNot Nothing Then
            ' Remove existing handler first to avoid duplicate triggers
            RemoveHandler comboBox.SelectedIndexChanged, AddressOf ComboBox_SelectedIndexChanged
            
            ' Clear old items and add new ones
            comboBox.Items.Clear()
            comboBox.Items.AddRange({1, 2})
            
            ' Attach the selection change handler
            AddHandler comboBox.SelectedIndexChanged, AddressOf ComboBox_SelectedIndexChanged
        End If
    End If
End Sub

2. Replace the Cell with a TextBox on Selection #

Now, update your selection handler to properly replace the cell type instead of modifying the Value property:

Private Sub ComboBox_SelectedIndexChanged(sender As Object, e As EventArgs)
    Dim combo1 As ComboBox = CType(sender, ComboBox)
    If combo1.SelectedIndex = 0 Then
        ' First, end the current editing session—you can't replace a cell while it's being edited
        DataGridView1.EndEdit()
        
        ' Get the current cell's position
        Dim colIndex = DataGridView1.CurrentCell.ColumnIndex
        Dim rowIndex = DataGridView1.CurrentCell.RowIndex
        
        ' Create a new TextBox cell and set its value
        Dim textBoxCell As New DataGridViewTextBoxCell()
        textBoxCell.Value = "S"
        
        ' Replace the original ComboBox cell with the new TextBox cell
        DataGridView1.Rows(rowIndex).Cells(colIndex) = textBoxCell
        
        ' Optional: Immediately enter edit mode on the new TextBox if needed
        DataGridView1.BeginEdit(True)
    End If
End Sub

Key Notes to Remember #

• Always call EndEdit() first: You can't modify the cell type while the cell is in edit mode—this is a common pitfall!
• Replace the cell object, not the value: Instead of setting CurrentCell.Value, you need to overwrite the cell in the Cells collection with your new DataGridViewTextBoxCell.
• Avoid duplicate event bindings: Removing and re-adding the SelectedIndexChanged handler prevents the event from firing multiple times as you edit different cells.

If your DataGridView is bound to a data source, you might need to adjust this logic to work with your data model, but for unbound grids, this should solve your problem perfectly.

内容的提问来源于stack exchange，提问作者harizh