Question

我有一个自定义控件，里面有一个DropDownList，它是由CreateUserControl创建的。我将数据源直接保存到下拉控件。页面回发后，我的绑定数据消失。我应该以一种棘手的方式自己保存/恢复我的绑定数据吗？

public class EnumDropDownList : UserControl
{
    private readonly DropDownList _ddlSelector;
    private Dictionary<long, string> _dataSource;

    public EnumDropDownList()
    {
        _ddlSelector = new DropDownList();
        _dataSource = new Dictionary<long, string>();
    }


    public object DataSource
    {
        set
        {
            // datasource logic
        }
    }

    public long SelectedValue
    {
        get { return Convert.ToInt64(_ddlSelector.SelectedValue); }
        set { _ddlSelector.SelectedValue = value.ToString(); }
    }

    public override void DataBind()
    {
        _ddlSelector.DataSource = _dataSource;
        _ddlSelector.DataTextField = "Value";
        _ddlSelector.DataValueField = "Key";
        _ddlSelector.DataBind();

        base.DataBind();
    }

    [PermissionSet(SecurityAction.Demand, Name = "Execution")]
    protected override void CreateChildControls()
    {
        Controls.Add(_ddlSelector);
    }
}

Answer 1

在某些情况下，我已将数据集保存在会话变量中。然后可以在回发后引用。像这样：

Session.Add("dataSource", _dataSource);//create the session variable

然后你可以引用它，具体取决于数据源的类型（例如我使用了数据源）

_ddlSelector.DataSource = (DataTable)Session["dataSource"];

Answer 2

您的代码是UserControl和CustomServerControl的组合。

如果你实现一个而不是组合，可能会容易得多。

我创建了两个控件 - UserControl和CustomServerControl。

<强>用户控件

将下拉列表放在ASPX上，而不是加载dymaiclally。如果动态加载，则必须注意控件的持久性。

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="EnumDropDownList.ascx.cs"
    Inherits="WebApplication2010.EnumDropDownList" %>
<asp:DropDownList runat="server" ID="DropDownList1" />

public partial class EnumDropDownList : System.Web.UI.UserControl
{
    private Dictionary<long, string> _dataSource;

    public EnumDropDownList()
    {
        _dataSource = new Dictionary<long, string>();
    }

    public Dictionary<long, string> DataSource
    {
        set { _dataSource = value; }
    }

    public long SelectedValue
    {
        get { return Convert.ToInt64(DropDownList1.SelectedValue); }
        set { DropDownList1.SelectedValue = value.ToString(); }
    }

    public override void DataBind()
    {
        DropDownList1.DataSource = _dataSource;
        DropDownList1.DataTextField = "Value";
        DropDownList1.DataValueField = "Key";
        DropDownList1.DataBind();

        base.DataBind();
    }
}

自定义服务器控件（为您的案例实施起来要容易得多）

它基本上继承了DropDownList Web控件。

public class MyDropDownList : DropDownList
{
    public long SelectedInt64Value
    {
        get { return Convert.ToInt64(SelectedValue); }
        set { SelectedValue = value.ToString(); }
    }

    public Dictionary<long, string> DataSource
    {
        get { return (Dictionary<long, string>)ViewState["DataSource"]; }
        set { ViewState["DataSource"] = value; }
    }

    public override void DataBind()
    {
        foreach (var item in DataSource)
            Items.Add(new ListItem(item.Value, item.Key.ToString()));

        base.DataBind();
    }
}

<强>用法

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm5.aspx.cs" Inherits="WebApplication2010.WebForm5" %>

<%@ Register Src="EnumDropDownList.ascx" TagName="EnumDropDownList" TagPrefix="uc1" %>
<%@ Register TagPrefix="asp" Namespace="WebApplication2010" Assembly="WebApplication2010" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <uc1:EnumDropDownList ID="EnumDropDownList1" runat="server" />
    <asp:Button runat="server" ID="Button1" Text="Submit" OnClick="Button1_Click" />
    <asp:MyDropDownList id="MyDropDownList1" runat="server" />
    </form>
</body>
</html>

protected void Page_Load(object sender, EventArgs e)
{
    if(!IsPostBack)
    {
        Dictionary<long, string> dataSource  = new Dictionary<long, string>();
        dataSource.Add(1, "One");
        dataSource.Add(2, "Two");

        EnumDropDownList1.DataSource = dataSource;
        EnumDropDownList1.DataBind();

        MyDropDownList1.DataSource = dataSource;
        MyDropDownList1.DataBind();
    }
}

Answer 3

这是aspx文件：

                <telerik:RadComboBox ID="cmbCurrency" runat="server" Width="200px" MaxHeight="200px"
                    EmptyMessage="Select a currency" AutoPostBack="true" Filter="Contains" EnableLoadOnDemand="true">
                </telerik:RadComboBox>

这是代码背后：

 if (!IsPostBack)
            {
                popCurrencyName();              
            }    

    public void popCurrencyName()
                {
                    DataTable dtCurrency = objCurrencyBAL.getCurrency(long.MinValue);

                    if (dtCurrency.Rows.Count > 0)
                    {
                        cmbCurrency.DataSource = dtCurrency;
                        cmbCurrency.DataTextField = "Name";
                        cmbCurrency.DataValueField = "CurrencyId";
                        cmbCurrency.DataBind();
                    }
                }

试试这段代码：

自定义用户控制数据源

3 个答案: