GridView 裡實現連動下拉選單
以下範例可以實現在GridView裡，做到連動式下拉選單
一開始先在GridView裡二個Cell的Template裡放入DropDownList
暫名為DropDownList1及DropDownList2
考量到效能問題，所以一開始先下一次SQL把DropDownList1所需要的item資料放到一個DataTable裡
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowIndex > -1)
{
if (e.Row.FindControl("DropDownList1") != null) { DropDownList droplist1 = e.Row.FindControl("DropDownList1") as DropDownList; droplist1.DataSource = dt; //dt為一個DataTable droplist1.DataTextField = "name"; droplist1.DataValueField = "id"; droplist1.DataBind();
} }
}接著在DropDownList1的SelectedIndexChanged事件去處理DropDownList2的item , 這裡有二種方式可以達成
分列如下
方法(1)
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e){ DropDownList DropDownList1 = ((DropDownList)sender); //方法1 DropDownList DropDownList2 = DropDownList1.NamingContainer.FindControl("DropDownList2") as DropDownList; DropDownList2.Items.Clear(); DropDownList2.Items.Add(new ListItem(DropDownList1.SelectedValue, DropDownList1.SelectedValue));}
方法(2)
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e){ DropDownList DropDownList1 = ((DropDownList)sender); //方法2 DropDownList DropDownList2 = DropDownList1.Parent.FindControl("DropDownList2") as DropDownList; DropDownList2.Items.Clear(); DropDownList2.Items.Add(new ListItem(DropDownList1.SelectedValue, DropDownList1.SelectedValue));}
這樣就可以囉
是不是很簡單啊，不過就如一開始所說的，在考量效能上所以先採用DataTable的方法來放Data，而效能卻往往也是寫程式最容易忽略的
這樣的好處是在於接下來不用跑GriveView的RowDataBound事件裡多跑太多次SQL
DropDownList1的item利用GridView1_RowDataBound事件先Bind進來
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By No.18
