在ASP.net的父列表项下创建子列表项 [英] Create child list items under parent list item in ASP.net

问题描述

嗨！
如何在不使用数据库的情况下将子列表项添加到ASP.net下拉列表中的父列表项中?

Hi!
How can I add child list items to a parent list item in a dropdown list in ASP.net without using a database?

Thanks in advance!

推荐答案

您不能在下拉菜单中包含父"列表项和子"列表项，如下所示:

You can''t have a Parent list item and Child list items in a drop down like this:

Parent1
   Child 1
   Child 2
Parent 2
   Child 3
      Child 4
      Child 5
   Child 6

下拉菜单无法像这样工作-它仅支持一个级别:

Drop down just doesn''t work like that - it only supports a single level:

Item 1
Item 2
Item 3

相反，考虑使用TreeView(如果需要真正的层次结构列表)，或者如果仅需要一个级别，则使用两个下拉列表.当第一个更改时，它将更改第二个的内容.

Instead, consider a TreeView (if you need a truly hierarchical list) or use two drop downs if you only need one level. When the first changes, it alters the content of the second.

this[^] might help you.

public partial class Default : System.Web.UI.Page
{
    // First DropdownList items
    protected string[] Movies ={ "select a movie", "Movie_1", "Movie_2", "Movie_3" };
    // Second DropdownList items. One among these to be choosen.
    protected string[] Movie_1={"Theatre_1","Theatre_2","Theatre_3"};
    protected string[] Movie_2 ={ "Theatre_4", "Theatre_5" };
    protected string[] Movie_3 ={ "Theatre_5", "Theatre_6", "Theatre_7" };
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DropDownList1.DataSource = Movies;
            DropDownList1.DataBind();
        }
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (DropDownList1.SelectedIndex == 1)
        {
            DropDownList2.DataSource = Movie_1;
            DropDownList2.DataBind();
        }
        if (DropDownList1.SelectedIndex == 2)
        {
            DropDownList2.DataSource = Movie_2;
            DropDownList2.DataBind();
        }
        if (DropDownList1.SelectedIndex == 3)
        {
            DropDownList2.DataSource = Movie_3;
            DropDownList2.DataBind();
        }
    }
}

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