从 Gridview 内的下拉列表中永久删除项目

Question

我在 Gridview 中有下拉列表，例如，

<asp:TemplateField HeaderText="Leave Category" >
    <ItemTemplate>
        <asp:DropDownList ID="LCList" runat ="server"  AutoPostBack="true" OnSelectedIndexChanged="LCList_TextChanged"/>
    </ItemTemplate>
</asp:TemplateField>

并添加类似的项目，

protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DropDownList LCList = (e.Row.FindControl("LCList") as DropDownList);
        LCList.Items.Insert(0, new ListItem("casual Leave"));
        LCList.Items.Insert(1, new ListItem("sick Leave"));
        LCList.Items.Insert(2, new ListItem("LOP"));
    }
}

如果我选择 LOP 一次，它应该从网格的选定行下拉列表中删除。不会再显示了。

上面的代码正在运行。但是如果我刷新页面，它正在显示

如何解决？

是否需要在任何其他事件中创建项目？

Answer 1

在回发中（当您刷新页面时），DataBound 方法再次被执行，这就是您看到所有值的原因。在将数据绑定到网格之前，您必须调整数据绑定方法以检查值。

就在您的 Databind 调用之前...

// 检查是否有任何 Grid 值选择了 LOP

if (DataTable.Select(dr => dr.dropDown.Value = "LOP").Count > 0) 
{
 blnIsLOPselected = True;
}

DataGrid.DataSource = <dataTable>
DataGrid.DataBind();

在你的 DataBind 中

protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DropDownList LCList = (e.Row.FindControl("LCList") as DropDownList);
        LCList.Items.Insert(0, new ListItem("casual Leave"));
        LCList.Items.Insert(1, new ListItem("sick Leave"));

        If (!blnIsLOPselected )
        {
           LCList.Items.Insert(2, new ListItem("LOP"));
        }
    }
}

Answer 2

显示它是因为您必须将从 DropDownList 中删除的值存储在某个地方，例如 Session。您必须保存行号和删除的值，然后在构建 GridView 时将 DropDown 中的值与已删除的值进行比较。

//create a list with keyvalue pairs to hold the removed items
public static List<KeyValuePair<int, string>> itemsRemoved = new List<KeyValuePair<int, string>>();

protected void Page_Load(object sender, EventArgs e)
{
    //check if the session with the removed items exists and if so cast back to a list
    if (Session["itemsRemoved"] != null)
    {
        itemsRemoved = Session["itemsRemoved"] as List<KeyValuePair<int, string>>;
    }

    //bind the gridview
    if (!Page.IsPostBack)
    {
        GridView1.DataSource = Common.LoadFromDB();
        GridView1.DataBind();
    }
}

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    //check if the row is a normal datarow
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        DropDownList LCList = (e.Row.FindControl("LCList") as DropDownList);

        //create an array with the dropdown option for easier looping
        string[] listItems = new string[] { "casual Leave", "sick Leave", "LOP" };

        for (int i = 0; i < listItems.Length; i++)
        {
            bool wasRemoved = false;

            //check if the listitem was remove for this row
            for (int j = 0; j < itemsRemoved.Count; j++)
            {
                if (e.Row.RowIndex == itemsRemoved[j].Key && listItems[i] == itemsRemoved[j].Value)
                {
                    wasRemoved = true;
                }
            }

            //if not removed, add it to the dropdownlist
            if (wasRemoved == false)
            {
                LCList.Items.Insert(LCList.Items.Count, new ListItem(listItems[i]));
            }
        }
    }
}

protected void LCList_SelectedIndexChanged(object sender, EventArgs e)
{
    //cast the sender back to a dropdownlist
    DropDownList LCList = sender as DropDownList;

    //get tne namingcontainer from the dropdownlist to get the rownumber
    GridViewRow row = (GridViewRow)LCList.NamingContainer;
    int rowIndex = row.RowIndex;

    //create a new keyvalue pair with the correct rowindex and selected value
    KeyValuePair<int, string> kv = new KeyValuePair<int, string>(rowIndex, LCList.SelectedValue);

    //add it to the list with removals
    itemsRemoved.Add(kv);

    //remove from the dropdownlist immediately
    LCList.Items.RemoveAt(LCList.SelectedIndex);
}