How to add Item to SqlDataSource databound list

问题

I am lazy - and I am using a SQLDataSource to populate my dropdownLists.

The Databind event for the databound objects is called before the Page.PreRender so I am doing something like this in the PreRender eventHandler:

private void InitializeDropDown()
        {
            this.myDropDown.Items.Insert(0, new ListItem("-- Select something --"));
        }

I know I can set AppendDataBound items to true and hardcode my custom item in the markup but before reverting to that I'd like to understand why what I am doing is not working.

It usually works when I bind stuff dynamically like this:

myDropDown.DataTextField = "whatever";
myDropDown.DataValueField = "ID";
myDropDown.DataSource = GetStuff();
myDropDown.DataBind();
myDropDown.Items.Insert(0, "-- Select something --");

What I am doing should be equivalent - only difference is I am using a SQLDataSource.

Any help appreciated!

回答1:

Put your insert line on the OnSelected method of the datasource

myDropDown.Items.Insert(0, "-- Select something --");

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.sqldatasource.selected.aspx

回答2:

I set AppendDataBoundItems="true" for the dropDwonList and it works like charme! I thought it was supposed to be used only in presence of hardcoded list items in the markup. I was wrong.

来源：https://stackoverflow.com/questions/551957/how-to-add-item-to-sqldatasource-databound-list