c# - 使用 DropDownList 控件更新 GridView

Question

我的代码中有以下行：

cmd.Parameters.Add("@priority", SqlDbType.VarChar).Value = ((DropDownList)GridView1.Rows[e.RowIndex].Cells[4].Controls[0]).SelectedValue;

但是当我运行它时，我收到以下错误：

Unable to cast object of type 'System.Web.UI.LiteralControl' to type 'System.Web.UI.WebControls.DropDownList'.

知道为什么会这样吗？

---

GridView 的相关部分是这样的：

<asp:TemplateField HeaderText="Priority">
    <ItemTemplate>
        <asp:Label ID="Label1" runat="server" Text='<%# Bind("priority") %>'></asp:Label>
    </ItemTemplate>
    <EditItemTemplate>
        <asp:DropDownList ID="DropDownList1" runat="server" 
            SelectedValue='<%# Bind("priority") %>'>
            <asp:ListItem Value="0">Low</asp:ListItem>
            <asp:ListItem Value="1">Normal</asp:ListItem>
            <asp:ListItem Value="2">High</asp:ListItem>
        </asp:DropDownList>
    </EditItemTemplate>
</asp:TemplateField>

Answer 1

由于您DropDownList最有可能在 a 中TemplateField，因此您可以通过以下方式获得它的参考FindControl("ID")：

public void gv_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridView gv = (GridView)sender;
    GridViewRow row = gv.Rows[e.RowIndex];
    // assuming its ID is "DropDownList1"
    DropDownList ddl = (DropDownList)row.FindControl("DropDownList1"); 
    String selectedValue = ddl.SelectedValue;

Answer 2

您必须e.Item.FindControl在 RowDataBound 中使用

var ddl = (DropDownList) e.Item.FindControl("YourId");
var value = ddl.SelectedValue;

Answer 3

这会成功的

public void gv_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    string spacediv3 = ((DropDownList)gridviewname.Rows[e.RowIndex].Cells[location].FindControl("dropdownlit1")).SelectedItem.ToString();
}