Question

I have a DataGridView with read-only mode set to true (non-editable) which takes values from a database on form load. When I set the read-only mode to false (editable mode), I want a particular column (eg. Department) to visible as ComboBox so i can select values from there. And when i enter the Read-Only mode, the ComboBox should disappear and DataGridView should be visible as normal. How to achieve it?
I am using C# framework 4.0, Winforms

Answer 1

See the implementation at ComboBox with read only behavior.

You could also change the DisplayStyle based on when the readonly of the DataGridView property is changed. Setting the DisplayStyle to DataGridViewComboBoxDisplayStyle.Nothing will hide the drop down button.

For example, changing the ReadOnly property with a button click would look something like this:

private void mChangeReadOnlyButton_Click(object sender, EventArgs e)
{
   ComboBoxColumn2.DisplayStyle = (dataGridView1.ReadOnly) ?
      DataGridViewComboBoxDisplayStyle.ComboBox :
      DataGridViewComboBoxDisplayStyle.Nothing;
   dataGridView1.ReadOnly = !dataGridView1.ReadOnly;
}

Editable:

ReadOnly: