0

在嵌套中继器的页脚中查找数量框控件时出现空引用错误。执行 OnItemCommand 函数时会发生错误（而不是数据绑定到中继器时，这是我之前遇到但已修复的问题）。

我是新手，所以我不明白这一切，我正在努力解决它，但我不知道为什么在 foreach 重复项中 FindControl （msdn 说包括标题和转发器的页脚！）在该转发器的页脚中找不到控件。它快把我逼疯了。

请帮忙！

更新：我更改了代码，但仍然遇到同样的问题——我错误地引用了 ddl，并且我不断得到对象引用未设置为对象的实例。

这是代码：

。网：

    <asp:Content ID="ProductRepeater" ContentPlaceHolderID="ProductRepeater" Runat="Server">
  <asp:Repeater ID="chairRepeater" OnItemCommand="productRepeater_ItemCommand" OnItemDataBound="chairRepeater_ItemDataBound" runat="server">
    <ItemTemplate>
      ...
      <asp:Repeater ID="variantRepeater" OnItemDataBound="variantRepeater_ItemDataBound" runat="server">
        <ItemTemplate>
          <li>
            <asp:RadioButton ID="radioBtn" GroupName="collections" runat="server"></asp:RadioButton>
            <asp:HiddenField ID="variantId" runat="server" />
            <asp:Literal ID="Image1" runat="server" />
            &nbsp;
            <asp:Literal ID="collectionName" runat="server" />
            &nbsp;&ndash;&nbsp;
            <asp:Literal ID="listPrice" runat="server" />
          </li>
        </ItemTemplate>
        <FooterTemplate>
        </ul>
          <asp:DropDownList ID="quantityLister" runat="server" />
        </FooterTemplate>
      </asp:Repeater>
         <asp:ImageButton ID="addToCart" ImageUrl="assets/images/_addtocart.gif"  runat="server" />
      </div>
      </div>
    </ItemTemplate>
    <SeparatorTemplate> <br />
    </SeparatorTemplate>
    <FooterTemplate> </FooterTemplate>
  </asp:Repeater>

C＃：

protected void productRepeater_ItemCommand(object source, RepeaterCommandEventArgs e)
{
    BasketHelper basketHelper = new BasketHelper(SiteContext.Current.ShoppingBasketName);
    OrderForm orderForm = basketHelper.GetOrderForm();
    bool basketUpdated = false;

    string catalogName = ConfigurationManager.AppSettings["PatioCatalogName"];
    string productId = ((HiddenField)e.Item.FindControl("productId")).Value;
    string variantId = "";

    Repeater variantRepeater = (Repeater)e.Item.FindControl("variantRepeater");
    foreach (RepeaterItem item in variantRepeater.Items)
    {
        RadioButton radioBtn = item.FindControl("radioBtn") as RadioButton;

        if (radioBtn.Checked == true)
        {
            variantId = ((HiddenField)item.FindControl("variantId")).Value;
        }
    }
        int quantity = 0;
        DropDownList quantityLister = (DropDownList)variantRepeater.FindControl("quantityLister");
        string ddlvalue = quantityLister.SelectedValue;
        int.TryParse(ddlvalue, out quantity);

        if (quantity > 0)
        {
            orderForm.LineItems.Add(new LineItem(catalogName, productId, variantId, quantity));
            basketUpdated = true;
        }
    if (basketUpdated)
    {
        basketHelper.Basket.Save();

        Response.Redirect(
            String.Format(
                CultureInfo.InvariantCulture,
                "~/cart.aspx?{0}={1}",
                SiteConstants.ActionQueryStringKey,
                SiteConstants.RunPipelineCartAction),
            true);
    }
}

这是我按下购买按钮时遇到的错误：

Server Error in '/' Application.
Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:

Line 116:            int quantity = 0;
Line 117:            DropDownList quantityLister = (DropDownList)variantRepeater.FindControl("quantityLister");
Line 118:            string ddlvalue = quantityLister.SelectedValue;
Line 119:            int.TryParse(ddlvalue, out quantity);
Line 120:


Source File: c:\Inetpub\patios\chaircovers.aspx.cs    Line: 118

Stack Trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   ChairCovers.productRepeater_ItemCommand(Object source, RepeaterCommandEventArgs e) in c:\Inetpub\patios\chaircovers.aspx.cs:118
   System.Web.UI.WebControls.Repeater.OnItemCommand(RepeaterCommandEventArgs e) +108
   System.Web.UI.WebControls.Repeater.OnBubbleEvent(Object sender, EventArgs e) +68
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.RepeaterItem.OnBubbleEvent(Object source, EventArgs e) +123
   System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args) +37
   System.Web.UI.WebControls.ImageButton.OnCommand(CommandEventArgs e) +111
   System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument) +176
   System.Web.UI.WebControls.ImageButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565
4

2 回答 2

1

所以我改变了这个：

DropDownList quantityLister = (DropDownList)variantRepeater.FindControl("quantityLister");

对此：

DropDownList quantityLister = variantRepeater.Controls[variantRepeater.Controls.Count - 1].FindControl("quantityLister") as DropDownList;

它奏效了。

于 2009-12-30T21:52:16.807 回答
0

自从我这样做以来已经有一段时间了，但作为一个尝试的想法，

由于它是嵌套的，因此 html 中嵌套的页眉或页脚控件的实际名称是外部转发器控件名称（我认为）、下划线 ('_') 和内部页眉/页脚名称的串联控制...你在你的发现中使用这个吗？

第二个建议：更改您的代码

foreach (RepeaterItem item in variantRepeater.Items)
{
      decimal quantity = 0;        
      decimal.TryParse(((DropDownList)item.FindControl(
             "quantityLister")).SelectedValue, out quantity); 
      if (quantity > 0)
      {   
          string variantId = ((HiddenField)item.FindControl("variantId")).Value;
          orderForm.LineItems.Add(
                 new LineItem(catalogName, productId, variantId, quantity));
          basketUpdated = true; 
      }
}

并将其更改为：

foreach (RepeaterItem item in variantRepeater.Items)
{
      decimal quantity = 0;        
      decimal.TryParse(((DropDownList)item.FindControl(
             "quantityLister")).SelectedValue, out quantity); 
      if (quantity > 0)
      { 
          if (item == null)
              throw new ApplicationException(
                  "Can't locate RepeaterItem");
          object obj = item.FindControl("variantId");
          if (obj == null)
          {
              string sNL = Environment.NewLine;
              StringBuilder sb = new StringBuilder(
                     "Can't locate variantId HiddenField" + sNL +
                     "item Controls are:" + sNL); 
              foreach(Control ctrl in item.Controls)
                  sb.Append(ctrl.Name + sNL);

              throw new ApplicationException(sb.ToString());                
          }
          if (!(obj is HiddenField))
              throw new ApplicationException(
                  "variantId is not a HiddenField");
          HiddenField hfld = obj as HiddenField;

          string variantId = hfld.Value;
          orderForm.LineItems.Add( new LineItem(
                 catalogName, productId, variantId, quantity));
          basketUpdated = true; 
      }
}

再次运行它，看看错误是什么......

于 2009-12-16T18:50:11.013 回答