DropDownList OnSelectedIndexChange未触发

Question

<asp:DropDownList ID="dropdownCountry" runat="server"                                         
                  CssClass="form-control form-control-dropdown"                                         
                  OnSelectedIndexChanged="dropdownCountry_SelectedIndexChanged"  
                  EnableViewState="true" AutoPostBack="true">
 </asp:DropDownList>

protected void dropdownCountry_SelectedIndexChanged(object sender, EventArgs e)
{
    var countryId = Convert.ToInt32(dropdownCountry.SelectedValue);
    var states = from st in model.states
                 where st.CountryId == countryId
                 select st;
    dropdownState.DataValueField = "StateId";
    dropdownState.DataTextField = "State1";
    dropdownState.DataSource = states;
    DataBind();
}

我设置了EnableViewState="true"和AutoPostBack="true"两个值。我的页面加载事件被触发但dropdownCountry_SelectedIndexChanged未被触发

Answer 1

在Page_Load

上使用!Page.IsPostBack