Question

在ListView＆＃39; ItemDataBound中，我有一个DropDownList控件。 DropDownList填充在ListView的{{1}}方法中（我发现只有这样才能在EditTemplate中填充列表...... DropDownList只存在于EditTemplate中;它必须是一个标签在ItemTemplate）。

列表填充，一切正常。我遇到的问题是，当单击“更新”按钮并调用ItemUpdating方法时，DropDownList的SelectedIndex 总是为零，无论选择哪个值时间。

aspx代码减去额外的模板如下所示：

<asp:ListView ID="ListView1" runat="server" OnItemDataBound="ListView1_ItemDataBound" OnItemUpdating="ListView1_ItemUpdating" OnItemEditing="ListView1_ItemEditing">
<EditItemTemplate>
    <tr style="">
    <td><asp:DropDownList CssClass="vaultDropDownList" ID="EditStaffList" runat="server" AutoPostBack="false" CausesValidation="True"></asp:DropDownList></td>
    <td>
       <asp:LinkButton ID="UpdateButton" runat="server" CommandName="Update" Text="Update" />
       <asp:LinkButton ID="CancelButton" runat="server" CommandName="Cancel" Text="Cancel" />
    </td>
    </tr>
    </EditItemTemplate>
</asp:ListView>

代码隐藏：

protected void ListView1_ItemEditing(object sender, ListViewEditEventArgs e)
{            
    ListView1.EditIndex = e.NewEditIndex;
}

protected void ListView1_ItemDataBound(object sender, ListViewItemEventArgs e)
{
    if (e.Item.DisplayIndex == ListView1.EditIndex)
    {
        DropDownList ddl = e.Item.FindControl("EditStaffList") as DropDownList;
        BindDropDownList(ddl);
    }
}

protected void ListView1_ItemUpdating(object sender, ListViewUpdateEventArgs e)
{
   DropDownList staff = ListView1.Items[e.ItemIndex].FindControl("EditStaffList") as DropDownList;

   //SQL update stuff will go here
   ListView1.EditIndex = -1;
}

如果我尝试在Page_Load方法中填充DropDownList以使用IsPostBack，则下拉控件始终返回null。

任何帮助都非常感谢！

编辑：ListView绑定：

protected void DisplayListView(object sender, EventArgs e) 
{ 
    string connString = SQLstringTooLong; 
    SqlConnection sqlConnection = new SqlConnection(connString); 
    DataTable initialTable = new DataTable(); 
    string queryStatement = "SELECT lotsastuff"; 
    SqlDataAdapter dataAdapter = new SqlDataAdapter(queryStatement, sqlConnection); 
    dataAdapter.Fill(initialTable); 
    ListView1.DataSource = initialTable; 
    ListView1.DataBind(); 
}

Edit2：这是dropdownlist绑定方法：

public static void CreateStaffList(DropDownList list, string searchGroup) 
{ 
    ArrayList userList = new ArrayList(); 
    //more SQL stuff 
    list.DataSource = userList; 
    list.DataBind(); 
}

Answer 1

确保您不会在每个PostBack上绑定ListView。把它包裹起来以检查它。

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DisplayListView();
    }
}

如果您不这样做，您的整个ListView（包括DropDownLists）都会重新绑定。这会导致DropDownList将其SelectedIndex重置为0。

ListView的OnItemUpdating方法中的ASP.NET DropDownList的SelectedIndex总是为0

1 个答案: