List box validation in asp.net

Question

Hi how to set required feild validator for multi select list box in asp.net?

I tried in default way something like

initial value = "0" for required feild validator. But it is not working for me.

Any example?

Answer 1

@jestges: chek this link i am sure it will hep you out.

Answer 2

U can use the custom validation for that..

 protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
    {
        if (ListBox1.Items.Count == 0)
        {
            args.IsValid = false;
        }
        else
        {
            args.IsValid = false;
        }
    }

may be this will help you

Answer 3

A small correction to your code is in order since it always returns false:

  protected void CustomValidator1_ServerValidate(object source, ServerValidateEventArgs args)
    {
       args.IsValid = (ListBox1.Items.Count > 0);
    }