如何將默認值設置爲下拉列表控件？

Question

我在我的網頁上有一個下拉列表控件。我已經將DataTable綁定到下拉列表控件，如下所示 -

lstDepartment.DataTextField = "DepartmentName"; 
    lstDepartment.DataValueField = "DepartmentID"; 
    lstDepartment.DataSource = dtDept; 
    lstDepartment.DataBind(); 

在頁面加載事件我想設置的默認值下拉列表控制從我的其他表字段

。

該怎麼辦？

Answer 1

假設在其他表DropDownList控件還包含DepartmentName的和DepartmentID的：

lstDepartment.ClearSelection(); 

foreach (var item in lstDepartment.Items) 
{ 
    if (item.Value == otherDropDownList.SelectedValue) 
    { 
    item.Selected = true; 
    } 
}

Answer 2

後您的DataBind()：

lstDepartment.SelectedIndex = 0; //first item 

or 

lstDepartment.SelectedValue = "Yourvalue" 

or 
//add error checking, just an example, FindByValue may return null 
lstDepartment.Items.FindByValue("Yourvalue").Selected = true; 

or 
//add error checking, just an example, FindByText may return null 
lstDepartment.Items.FindByText("Yourvalue").Selected = true; 

Answer 3

，如果你知道缺省值的項目的索引，只

lstDepartment.SelectedIndex = 1;//the second item 

或者如果你知道你想設置的值，只需要

lstDepartment.SelectedValue = "the value you want to set"; 

Answer 4

lstDepartment.DataTextField = "DepartmentName"; 
lstDepartment.DataValueField = "DepartmentID"; 
lstDepartment.DataSource = dtDept; 
lstDepartment.DataBind(); 
'Set the initial value: 
lstDepartment.SelectedValue = depID; 
lstDepartment.Attributes.Remove("InitialValue"); 
lstDepartment.Attributes.Add("InitialValue", depID); 

而在你的取消方法：

lstDepartment.SelectedValue = lstDepartment.Attributes("InitialValue"); 

並在您更新方法：

lstDepartment.Attributes("InitialValue") = lstDepartment.SelectedValue;