dropdown SelectedIndexChanged页面重新加载但值为null

问题描述

嗨


i有2个下拉列表，onselectedindexchanged和autopostback true



当我点击dropdown1页面重新加载时，当前选择listitem是selectbox中的默认值..，我根据dropdown1值从数据库填充dropdown2 ..

然后当我点击dropdown2时，页面重新加载但是dropdown2选择的索引保持为0或空白





什么是错误

Hi
i have 2 dropdown with onselectedindexchanged and autopostback true

when i click dropdown1 the page reloads ,and current select listitem is default in selectbox.., i fill dropdown2 from database depending on dropdown1 value..
then when i click dropdown2 ,page reloads but the dropdown2 selected index remains 0 or blank


what is error

<asp:DropDownList ID="DropCity"  AutoPostBack="True"   onselectedindexchanged="DropCity_SelectedIndexChanged"   runat="server" >
                    </asp:DropDownList>

<asp:DropDownList ID="DropCity1"  AutoPostBack="True"   onselectedindexchanged="DropCity1_SelectedIndexChanged"   runat="server" >
                    </asp:DropDownList>

protected void DropCity1_SelectedIndexChanged(object sender, EventArgs e)
  {

DropCity.DataSource（）;

DropCity.databing（）;







}

DropCity.DataSource();
DropCity.databing();



}

protected void DropCity_SelectedIndexChanged(object sender, EventArgs e)
    {

}





请建议

}


please advice

推荐答案

drp1.DataTextField = "Test1";
               drp1.DataValueField = "TestID";
               drp1.DataSource = dt;

               drp1.DataBind();

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