如何在视图状态下维护用户控件值？

时间：2013-09-27 11:42:33

标签： c# asp.net user-controls viewstate

我想在视图状态

中维护用户控件值

我尝试了文本框，下拉值正在维护视图状态

但是BasicDatePicker值没有维护在视图状态我得到空值

代码：

的.aspx 

<asp:Repeater ID="rpt1" runat="server">
<ItemTemplate>
</ItemTemplate>
</asp:Repeater>
<asp:Button ID="addnewtext" runat="server" Text="Add" onclick="addnewtext_Click"  width="76px" />
<asp:Button ID="btnSaveVisa" Text="Save" runat="server" OnClick="btnSaveVisa_Click" />

.aspx.cs 

 private const string VIEWSTATEKEY = "ContactCount";
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            //Set the number of default controls
            ViewState[VIEWSTATEKEY] = ViewState[VIEWSTATEKEY] == null ? 1 : ViewState[VIEWSTATEKEY];

            //Load the contact control based on Vewstate key
            LoadContactControls();
        }
    }

    protected override void LoadViewState(object savedState)
    {
        base.LoadViewState(savedState);

        LoadContactControls();
    }


    private void LoadContactControls()
    {
        for (int i = 0; i < int.Parse(ViewState[VIEWSTATEKEY].ToString()); i++)
        {
          rpt1.Controls.Add(LoadControl("AddVisaControl.ascx"));
        }
    }

    protected void addnewtext_Click(object sender, EventArgs e)
    {
        LoadContactControls();
        ViewState[VIEWSTATEKEY] = int.Parse(ViewState[VIEWSTATEKEY].ToString()) + 1;

    }
    private void saveData()
    {
        foreach (var control in rpt1.Controls)
        {
            var usercontrol = control as AddVisaControl;

            string s = usercontrol.TextVisaNumber;
            string date = usercontrol.ExpiryDate.ToShortDateString();
        }
    }

    protected void Save_Click(object sender, EventArgs e)
    {
        saveData();
    }
   }

的.ascx

这里我添加了BasicDatePicker的程序集

   <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="AddVisaControl.ascx.cs" EnableViewState="false" Inherits="Pyramid.AddVisaControl" %>
   <%@ Register assembly="BasicFrame.WebControls.BasicDatePicker" namespace="BasicFrame.WebControls" tagprefix="BDP" %>
   <div id="divreg" runat="server">
   <table id="tbl" runat="server">
   <tr>
   <td>
    <asp:Label ID="lbl2" runat="server"></asp:Label>
   </td>
   </tr>
   <tr>
   <td> Visa Number:</td>
   <td><asp:TextBox ID="txtUser" Width="160px" runat="server"/></td>
   <td> Country Name:</td>
   <td><asp:DropDownList ID="dropCountry" Width="165px" runat="server">         </asp:DropDownList></td>
   </tr>
   <tr>
   <td> Type of Visa:</td>
   <td><asp:DropDownList ID="dropVisa" Width="165px" runat="server"></asp:DropDownList> </td>
   <td> Type of Entry:</td>
   <td><asp:DropDownList ID="dropEntry" Width="165px" runat="server"></asp:DropDownList></td>
   </tr>
   <tr>
    <td> Expiry Date</td>
   <td><BDP:BasicDatePicker ID="basicdate" runat="server"></BDP:BasicDatePicker></td>
   <td>
   <asp:Button ID="btnRemove" Text="Remove" runat="server" OnClick="btnRemove_Click" />
   </td>
   </tr>
   </table>
   </div>

.ascx.cs 

protected void Page_Load(object sender, EventArgs e)
{
    txtUser.Text = Request.Form[txtUser.UniqueID];
    dropCountry.SelectedValue = Request.Form[dropCountry.UniqueID];
    dropVisa.SelectedValue = Request.Form[dropVisa.UniqueID];
    dropEntry.SelectedValue = Request.Form[dropEntry.UniqueID];
    //Here I'm getting null value  
    basicdate.SelectedValue = Request.Form[basicdate.UniqueID];
}

public string TextVisaNumber
{
    get { return txtUser.Text; }
    set { txtUser.Text = value; }
}

public DateTime ExpiryDate
{
    get
    {
        return basicdate.SelectedDate;
    }
    set
    {
        basicdate.SelectedDate = value;
    }
}

在下面的图片中，当我给出文本框，下拉列表和日期选择器然后我单击添加按钮控件添加文本框，下拉值有，但是datepicker值消失

enter image description here

有什么想法吗？提前致谢

2 个答案:

答案 0 :(得分：0)

您可以将值存储在隐藏控件中并将值恢复到回发的相应控件中，如果涉及到jquery，我猜它是，它经常会在回发时忘记它的值，无论viewstate是否启用等等。

看看at this blog post使用隐藏字段值设置数据贴纸值。

以下博客文章的代码：

<table>
<tr>
    <td>
        <asp:CheckBox ID="chkEnableMonthlyNotifications" runat ="server" CssClass="cell-Text" Text="Enable monthly notifications." />
        <br/>
    </td>
</tr>
<tr>
    <td>
        <label for="txtMonthStartDate">Specify start date for monthly notification</label>
        <br />
        <br />
        <asp:TextBox ID="txtMonthStartDate" runat="server" Enabled="true"></asp:TextBox>
        <asp:HiddenField ID="hdnMonthStartDate" runat="server" />
    </td>
</tr>
<tr>
    <td>
        <label for="txtMonthEndDate">Specify end date for monthly notification, or leave blank if no end date.</label>
        <br />
        <br />
        <asp:TextBox ID="txtMonthEndDate" runat="server" Enabled="true" > </asp:TextBox>
        <asp:HiddenField ID="hdnMonthEndDate" runat="server" />
    </td>
</tr>
</table>

使用备用字段初始化Datepicker的jQuery 

$(document).ready(function ()
{
   $("[id$=_txtMonthStartDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnMonthStartDate]' });
   $("[id$=_txtMonthEndDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnMonthEndDate]' });
   $("[id$=_txtQuarterStartDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnQuarterStartDate]' });
   $("[id$=_txtQuarterEndDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnQuarterEndDate]' });
   $("[id$=_txtHalfYearStartDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnHalfYearStartDate]' });
   $("[id$=_txtHalfYearEndDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnHalfYearEndDate]' });
   $("[id$=_txtYearStartDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnYearStartDate]' });
   $("[id$=_txtYearEndDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnYearEndDate]' });
}

jQuery Code在document.ready

上再次设置Datepicker日期 
$(document).ready(function ()
{
  //Initializing the datepicker

  $("[id$=_txtMonthStartDate]").datepicker({ showOn: 'button', buttonImageOnly: true, buttonImage: '/icon_cal.png', altField: '[id$=_hdnMonthStartDate]' });

  //Code to set the datepicker's date again after post back
  if(!($("[id$=_txtMonthStartDate]").attr("Value") == undefined))
  {
    if($("[id$=_txtMonthStartDate]").attr("Value").length > 0)
    {
        $("[id$=_txtMonthStartDate]").datepicker("setDate",new Date($("[id$=_txtMonthStartDate]").val($("[id$=_txtMonthStartDate]").attr("Value"))));
    }
  }
}

答案 1 :(得分：0)

所以，这段代码与你的代码有点不同，但我知道它有效。我在这里工作了几个星期。我有一个预渲染，创建视图状态，并加载视图状态。每当我的一个值发生变化时，我就将它保存到我设置的私有属性中。 

    //Global ViewState Variables
    private DataTable networksInfo;
    private string HHmm;
    private string Window;
    private string ZoomFactorTop;
    private string ZoomFactorBottom;
    protected Boolean autoRefresh; 

    /// <summary>
    /// This page prerender allows me to save viewstate objects before anything bad
    /// happens. It's going to save any data that needs to persist across postbacks,
    /// since the page refreshes with an autorefresh. Whenever updated, the ViewState
    /// will also need to be updated.
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void Page_PreRender(object sender, EventArgs e)
    {
        // Save the ViewStateObjects before the page is rendered.
        ViewState.Add("networksListVS", networksInfo);
        ViewState.Add("HHmmVS", HHmm);
        ViewState.Add("WindowVS", Window);
        ViewState.Add("ZoomFactorTopVS", ZoomFactorTop);
        ViewState.Add("ZoomFactorBottomVS", ZoomFactorBottom);
        ViewState.Add("AutoRefresh", autoRefresh);
    }

    protected void Create_ViewState(DateTime now)
    {
        //Populate Dropdown handles the initial value for networksInfo, but none of the others are

        //Set ViewState Vars' initial values
        if (ViewState["HHmmVS"] == null)
        {
            int HH = now.Hour;
            int mm = now.Minute;

            Change_Time(HH, mm);

        }
        if (ViewState["WindowVS"] == null)
        {
            //The default time window to view is 6 hours
            Window = "6";
        }
        if (ViewState["ZoomFactorTopVS"] == null)
        {
            //The default zoom factor is Window + 0
            ZoomFactorTop = "0";
        }
        if (ViewState["ZoomFactorBottomVS"] == null)
        {
            //The default zoom factor is Window + 0
            ZoomFactorBottom = "0";
        }
        if(ViewState["AutoRefresh"] == null)
        {
            autoRefresh = true;
        }
    }

    protected void Load_ViewState()
    {
        //Before updating the charts, we know that this is a postback and that the viewstate shouldn't
        //be null, but check anyways, just to be sure
        if (ViewState["networksListVS"] != null)
        {
            networksInfo = (DataTable)ViewState["networksListVS"];
        }
        if (ViewState["HHmmVS"] != null)
        {
            HHmm = (String)ViewState["HHmmVS"];
        }
        if (ViewState["WindowVS"] != null)
        {
            Window = (String)ViewState["WindowVS"];
        }
        if (ViewState["ZoomFactorTopVS"] != null)
        {
            ZoomFactorTop = (String)ViewState["ZoomFactorTopVS"];
        }
        if (ViewState["ZoomFactorBottomVS"] != null)
        {
            ZoomFactorBottom = (String)ViewState["ZoomFactorBottomVS"];
        }
        if (ViewState["AutoRefresh"] != null)
        {
            autoRefresh = (Boolean)ViewState["AutoRefresh"];
        }
    }

我的一个变量实际上是一个日历对象。我使用它的方式是，如果用户选择较旧的时间，他们不希望页面刷新并且自动刷新关闭。

如果您不关心这一点，最简单的做法就是保存表示日期时间对象的状态。

现在，从我读过的东西，你需要一个预渲染（虽然这可以在页面加载中完成），一个创建视图状态（也可以在那里完成），以及一个加载视图状态。我看到的是你可能想要外部变量，而不是获取/设置，保存这些值的东西，因为当我保存我的viewstate时，它看起来更像是这样：

                ZoomFactorTop = "0";
                ZoomFactorBottom = "0";

                //Save the changes just made to the objects the ViewState needs access to
                SaveViewState();

希望有所帮助！

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