ASP.NET - User control custom data binding - asp.net

Question

I develop user control Date of Birth, which contains 3 DropDownList.
I need to make data binding, but I dunno how.
public partial class DofControl : System.Web.UI.UserControl {
public const int YearsCount = 100;
int _year;
Months _month;
protected void Page_Load(object sender, EventArgs e) {
if (!IsPostBack ) {
Bind();
}
if (SessionWrapper.JustInserted)
{
Bind();
SessionWrapper.JustInserted = false;
}
}
public object DataSource {
get; set;
}
private void Bind() {
int[] years = new int[YearsCount];
int from = DateTime.Now.Year - 5;
int to = from - 100;
for (int i = 0; i < YearsCount; i++) {
years[i] = to;
to++;
}
ddlYear.DataSource = years;
ddlYear.DataBind();
ddlMonth.DataSource = Enum.GetNames(typeof(Months));
ddlMonth.DataBind();
_year = Int32.Parse(ddlYear.SelectedValue);
_month = (Months)Enum.Parse(typeof(Months), ddlMonth.SelectedValue);
BindDays(_year, _month);
if (DataSource==null)
{
ddlYear.SelectedValue = years.Max().ToString();
ddlMonth.SelectedValue = Months.January.ToString();
ddlDay.SelectedValue = "1";
}
else
{
ddlYear.SelectedValue = Convert.ToDateTime(DataSource).Year.ToString();
ddlMonth.SelectedValue = Enum.GetName(typeof(Months), Convert.ToDateTime(DataSource).Month);
ddlDay.SelectedValue = Convert.ToDateTime(DataSource).Day.ToString();
}
}
enum Months { January = 1 //....... }
//Is this right?
[Bindable(true,BindingDirection.TwoWay)]
public DateTime Date {
private get {
return DateTime.Parse(string.Format("{0}/{1}/{2}", ddlDay.Text, ddlMonth.Text, ddlYear.Text));
}
set
{
ddlYear.SelectedValue = value.Year.ToString();
ddlMonth.SelectedValue = value.Month.ToString();
ddlDay.SelectedValue = value.Day.ToString();
}
}
protected void ddlMonth_SelectedIndexChanged(object sender, EventArgs e) {
_year = int.Parse(ddlYear.SelectedValue);
_month = (Months)Enum.Parse(typeof(Months), ddlMonth.SelectedValue);
BindDays(_year, _month);
}
protected void ddlYear_SelectedIndexChanged(object sender, EventArgs e) {
_year = int.Parse(ddlYear.SelectedValue);
_month = (Months)Enum.Parse(typeof(Months), ddlMonth.SelectedValue);
BindDays(_year, _month);
}
public bool IsLeapYear(int year) { //..... }
private void BindDays(int year, Months month) {
List<int> days = new List<int>();
switch (month) {
case Months.January:
case Months.March:
for (int i = 1; i <= 31; i++)
days.Add(i);
break;
case Months.February:
//does not matter
}
}
I use DofControl in a page Update.aspx inside asp:DetailsView.
<asp:ObjectDataSource ID="odsOneStudent" runat="server"
SelectMethod="GetStudentById"
..////
<asp:DetailsView
//......
<Fields>
<asp:BoundField DataField="SurName" HeaderText="SurName" />
<asp:TemplateField HeaderText="Dof">
<EditItemTemplate>
<uc:Dof runat="server" ID="dfDof" Date='<%#Eval("Dof") %>' />
</EditItemTemplate>
</asp:TemplateField>
</Fields>
</asp:DetailsView>
I does not work, I get an error "ddlMonth' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value"
Am I miss anything?
update: I get an error: "Databinding methods such as Eval(), XPath(), and Bind() can only be used in the context of a databound control"

Answer 1

When you set the SelectedValue of a DropDownList the value must be contained in the list's items.
Check where you are setting the SelectedValue that the value you are using is correct and contained in the DropDownList.Items