我有WebUserControl，由3个DropDownLists（日/月/年）组成。它有公共属性DateTime BirthDate。我在页面（Page_Load）上动态创建此WebUserControl。我希望能够在加载的WebUserControl中更改数据，并使用页面上的按钮保存它。
WebUserControl代码：
public DateTime BirthDate { get; set; }
protected void Page_Load(object sender, EventArgs e)
{
DropDownList dd = new DropDownList();
DropDownList dm = new DropDownList();
DropDownList dy = new DropDownList();
this.Controls.Add(dd);
this.Controls.Add(dm);
this.Controls.Add(dy);
dd.Items.Add(new ListItem("day","0"));
dm.Items.Add(new ListItem("month", "0"));
dy.Items.Add(new ListItem("year", "0"));
dd.Items.AddRange(GetNumericValues(1, 31).ToArray());
dm.Items.AddRange(GetNumericValues(1, 12).ToArray());
int yearNow = DateTime.Now.Year;
dy.Items.AddRange(GetNumericValues(yearNow - 100, yearNow - 17).ToArray());
dd.DataBind();
dm.DataBind();
dy.DataBind();
if (BirthDate != DateTime.MinValue)
{
dd.SelectedValue = BirthDate.Day.ToString();
dm.SelectedValue = BirthDate.Month.ToString();
dy.SelectedValue = BirthDate.Year.ToString();
}
else
{
dd.SelectedValue = "0";
dm.SelectedValue = "0";
dy.SelectedValue = "0";
}
}
private List<ListItem> GetNumericValues(int from, int to)
{
List<ListItem> n = new List<ListItem>();
for (int i = from; i <= to; i++)
{
n.Add(new ListItem(i < 10 ? "0" + i.ToString() : i.ToString()));
}
return n;
}
网页代码：
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
BirthDateWebUserControl bc = new BirthDateWebUserControl();
PanelForm.Controls.Add(bc);
ViewState["BirthDateWebUserControl"] = bc;
}
}
protected void Button1_Click(object sender, EventArgs e)
{
BirthDateWebUserControl bc = (BirthDateWebUserControl)ViewState["BirthDateWebUserControl"];
LabelResult.Text = bc.BirthDate.ToString("dd/MM/yy");
}
我做错了什么？
感谢
答案 0 :(得分：0)
必须在每页回发的Page PreInit或Init事件中创建动态创建的控件。 ASP.NET将刷新Init和Load事件之间控件的视图状态值。
答案 1 :(得分：0)
假设你有UserControl，如下所示：
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="Test.ascx.cs" Inherits="YourApplication.Test" %>
<asp:DropDownList ID="ddl1" runat="server" />
目标是能够获取并设置DropDownList的值，为此我们创建了UserControl能够执行此操作的属性。
public partial class Test : System.Web.UI.UserControl
{
public string Value
{
get { return ddl1.SelectedValue; }
set { ddl1.SelectedValue = value; }
}
}
然后我们可以将其用作其他页面上UserControl的属性。
<uc:Test ID="ucTest" runat="server" Value="1" />
或者
protected void Page_Load(object sender, EventArgs e)
{
string theValue = ucTest.Value;
}
答案 2 :(得分：0)
if you want to pass data to user (FindControl because added dynamicly)
you must use this
public partial class UserControl1 : System.Web.UI.UserControl
{
public string Property
{
get { return dd.SelectedValue; }
set { dd.SelectedValue = value; }
}
}
When you create, affect UniqueId to your user control
UserControl1 control = new UserControl1();
control.UniqueId="Test";
add.....
And find it in your page with PreInit event before other events
UserControl1 control = (UserControl1)Page.FindControl("Test");
control.Property = your value;
But if you want to pass data to your user control, this last must have this property with public modifier.
You can also pass with static forms as this example
<tagprefix:tagname id="" runat="server" Property="your value"/>
答案 3 :(得分：0)
这是您的控件+页面的工作版本。
用户控制：
using System;
using System.Collections.Generic;
using System.Web.UI.WebControls;
public partial class BirthDateWebUserControl : System.Web.UI.UserControl
{
private readonly string ViewStateKey = "BirthDateWebUserControl_VSKEY";
public DateTime BirthDate
{
get
{
int day = int.Parse(((DropDownList)this.FindControl("DayDropDown")).SelectedValue);
int month = int.Parse(((DropDownList)this.FindControl("MonthDropDown")).SelectedValue);
int year = int.Parse(((DropDownList)this.FindControl("YearDropDown")).SelectedValue);
return new DateTime(year, month, day);
}
set
{
((DropDownList)this.FindControl("DayDropDown")).SelectedValue = value.Day.ToString("00");
((DropDownList)this.FindControl("MonthDropDown")).SelectedValue = value.Month.ToString("00");
((DropDownList)this.FindControl("YearDropDown")).SelectedValue = value.Year.ToString("00");
}
}
protected void Page_Init(object sender, EventArgs e)
{
DropDownList dd = new DropDownList();
dd.ID = "DayDropDown";
DropDownList dm = new DropDownList();
dm.ID = "MonthDropDown";
DropDownList dy = new DropDownList();
dy.ID = "YearDropDown";
this.Controls.Add(dd);
this.Controls.Add(dm);
this.Controls.Add(dy);
if (ViewState[ViewStateKey] == null)
{
dd.Items.Add(new ListItem("day", "0"));
dm.Items.Add(new ListItem("month", "0"));
dy.Items.Add(new ListItem("year", "0"));
dd.Items.AddRange(GetNumericValues(1, 31).ToArray());
dm.Items.AddRange(GetNumericValues(1, 12).ToArray());
int yearNow = DateTime.Now.Year;
dy.Items.AddRange(GetNumericValues(yearNow - 100, yearNow - 17).ToArray());
dd.DataBind();
dm.DataBind();
dy.DataBind();
ViewState[ViewStateKey] = true;
}
}
private List<ListItem> GetNumericValues(int from, int to)
{
List<ListItem> n = new List<ListItem>();
for (int i = from; i <= to; i++)
{
n.Add(new ListItem(i < 10 ? "0" + i.ToString() : i.ToString()));
}
return n;
}
}
示例页面内容：
<asp:Panel ID="PanelForm" runat="server">
</asp:Panel>
<asp:Label ID="LabelResult" runat="server"></asp:Label>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Click" />
示例页面背后的代码：
protected void Page_Init(object sender, EventArgs e)
{
BirthDateWebUserControl bc = new BirthDateWebUserControl();
bc.ID = "bcInPanel";
PanelForm.Controls.Add(bc);
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
// init with some date in case not post back
((BirthDateWebUserControl)PanelForm.FindControl("bcInPanel")).BirthDate = new DateTime(1950, 4, 12);
}
}
protected void Button1_Click(object sender, EventArgs e)
{
var bc = (BirthDateWebUserControl)PanelForm.FindControl("bcInPanel");
LabelResult.Text = bc.BirthDate.ToString("dd/MM/yy");
}
需要考虑的一些要点：
Page_Init Page_Init ViewState中存储初始化控件所需的必要数据。不要存储整个控件本身。最重要的是：