Question

How can I set the value of my rad combobox if I keep getting this error message, even if the combobox has the ReadOnly="false" attribute set in the markup?

protected void Page_Init(object sender, EventArgs e)
{
    string dateArg = Request.QueryString["date"];

    if (dateArg != null)
    {
        rcbWeek.SelectedItem = rcbWeek.FindItemByText(dateArg);
    }
}

Answer 1

Here is how to do it, you can find it in the docs for the Rad Controls:

http://www.telerik.com/help/aspnet-ajax/combobox-items-server-side-code.html

//Use RadComboBoxItem.Selected
RadComboBoxItem item = RadComboBox1.FindItemByText("Item 2");
item.Selected = true;

//Use RadComboBox.SelectedIndex
int index = RadComboBox1.FindItemIndexByValue("2");
RadComboBox1.SelectedIndex = index;

//You can also use the SelectedValue property.
RadComboBox1.SelectedValue = value;