设置DataSource属性时，无法修改项目集合

Question

I get this error while trying to add items to the combobox at runtime.Is there a way to add items on runtime , even if my combobox datasource is set .

Example:My combobox has items , but i want to display "Select Category" type of statement when my form loads . Thanks !!!

Answer 1

Assuming

public class Product
{
    public int Id {get;set;}
    public string Name {get;set;}
}

with EF

var list = context.Products.Where(x = > x.Active == true).ToList(); 
list.Insert(0, new Product() { Id = -1, Name = "Please Select" }); 
selectBox.DataSource = list; 

The idea is to get your database list of objects into List < Product > () first, then simply add fake item on top of that list.

Answer 2

If all you want to do is display "Select Category", try this.

DropDownList1.Items.Insert(0, new ListItem("Select Category"));

I'm not sure if it's possible to do this after the DataBind() but I think it should be OK.