Column Count Error in datagridview

Question

public partial class sale_purchase_datagridview : DataGridView
    {
        private SqlConnection con;
        private SqlDataAdapter da;
        private DataTable dt, dt2;
        public sale_purchase_datagridview()
        {
            this.Columns[5].ReadOnly = true;
            InitializeComponent();
           
        }
        protected override void OnEnter(EventArgs e)
        {
            
            base.OnEnter(e);
           

        }

t

The problem is what i want is that , the column 5 of sale_purchase_datagridview must always be readonly . Although there is one thing due to this the error is popping , i have not add the columns in this custom datagridview itself . I have added the columns in the form where i am using this control . So is there a way by which i can achieve this ?

Answer 1

protected override void OnColumnAdded(DataGridViewColumnEventArgs e) {
    base.OnColumnAdded(e);
    if (e.Column.Index == 5) {
        e.Column.ReadOnly = true;
    }
}