How to programmatically set SelectedValue of Dropdownlist when it is bound to XmlDataSource

问题

I'm using XmlDataSource as the datasource for a dropdownlist.

Now I want to set the SelectedValue of the drop down when the page initially loads. I have tried the OnDataBound event of the drop down in which I could see the total items. But setting the SelectedValue didn't work. InOnDataBinding event, I couldn't even see the total items probably because the list isn't bound yet?

How can I set the selected index based on a value?

回答1:

This seems to work for me.

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            DropDownList1.DataBind(); // get the data into the list you can set it
            DropDownList1.Items.FindByValue("SOMECREDITPROBLEMS").Selected = true;
        }
    }

回答2:

DropDownList1.Items.FindByValue(stringValue).Selected = true; 

should work.

回答3:

This is working code

protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            { 
                    DropDownList1.DataTextField = "user_name";
                    DropDownList1.DataValueField = "user_id";
                    DropDownList1.DataSource = getData();// get the data into the list you can set it
                    DropDownList1.DataBind();

    DropDownList1.SelectedIndex = DropDownList1.Items.IndexOf(DropDownList1.Items.FindByText("your default selected text"));
            }
        }

回答4:

Have you tried, after calling DataBind on your DropDownList, to do something like ddl.SelectedIndex = 0 ?

来源：https://stackoverflow.com/questions/5121639/how-to-programmatically-set-selectedvalue-of-dropdownlist-when-it-is-bound-to-xm