当最后一项从网格视图中删除时，下拉列表不填充

Question

我很难确定这个问题的错误在哪里。我有一个ASP.NET Master.Page web应用程序，它有一个Gridview。我正在为EmptyDataTemplate中的下拉列表使用jquery选择的插件(如果有数据，则使用FooterControl )。

初始化时，如果没有网格的数据，则填充下拉列表并正确显示。如果网格中有项目，而我删除了所有项目，这样就没有数据，那么下拉列表就不会显示任何数据。调用DataBound事件，DataTable中包含所有正确的数据。它被绑在下坠处。但项目是否出现在列表中。这是我的标记：

<div id="DelegateGridWrapper">
    <asp:GridView ID="DelegateInfoGridView" runat="server" 
        AutoGenerateColumns="false" Caption="Delegate Information" 
        CaptionAlign="Top" CssClass="grid" RowStyle-Wrap="true" 
        HorizontalAlign="Left" ShowFooter="true" 
        AllowPaging="true" PageSize="5"  ShowHeaderWhenEmpty="false" onrowediting="DelegateInfoGridView_RowEditing" 
        onrowcancelingedit="DelegateInfoGridView_RowCancelingEdit" onrowdeleting="DelegateInfoGridView_RowDeleting" 
        onrowupdating="DelegateInfoGridView_RowUpdating" 
        ondatabound="DelegateInfoGridView_DataBound" 
        onrowcommand="DelegateInfoGridView_RowCommand">
        <Columns>
             <asp:TemplateField HeaderText="Recipient ID">
                <ItemTemplate>
                    <asp:Label ID="deligvLblRecipientID" runat="server" Text='<%# Bind("RecipientID") %>'></asp:Label>
                </ItemTemplate>
             </asp:TemplateField>

             <asp:TemplateField HeaderText="Delegate" ItemStyle-Wrap="false"> 
                <ItemTemplate>
                    <asp:Label ID="deligvLblRecipientName" runat="server" Text='<%# Bind("RecipientName") %>'></asp:Label>
                </ItemTemplate>
                <FooterTemplate>
                    <asp:DropDownList ID="deligvDDLRecipientName" runat="server" ClientIDMode="Static"
                                        data-placeholder="Choose delegate…" class="chosen-single">
                    </asp:DropDownList>
                </FooterTemplate>
             </asp:TemplateField>
             <asp:TemplateField HeaderText="Active"> 
                <ItemTemplate>
                    <asp:Label ID="deligvLblActive" runat="server" Text='<%# (Boolean.Parse(Eval("Active").ToString())) ? "Yes" : "No" %>'></asp:Label>
                </ItemTemplate>         
                 <EditItemTemplate>
                    <asp:DropDownList ID="deligvDDLActive" runat="server" Text='<%# (Boolean.Parse(Eval("Active").ToString())) ? "Yes" : "No" %>'>
                        <asp:ListItem>Yes</asp:ListItem>
                        <asp:ListItem>No</asp:ListItem>
                    </asp:DropDownList>
                </EditItemTemplate> 
                <FooterTemplate>
                    <asp:DropDownList ID="deligvDDLActiveInsert" runat="server">
                        <asp:ListItem Selected="True">Yes</asp:ListItem>
                        <asp:ListItem>No</asp:ListItem>
                    </asp:DropDownList>
                </FooterTemplate>                         
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Action" ItemStyle-Wrap="false" ItemStyle-HorizontalAlign="Center">
                 <ItemTemplate>
                    <asp:Button ID="deligvEditButton" runat="server" CausesValidation="False" CommandName="Edit" 
                                Text="Edit" CssClass="gridActionbutton">
                    </asp:Button>
                    &nbsp;<asp:Button ID="deligvDeleteButton" runat="server" CausesValidation="False" CommandName="Delete" ClientIDMode="Static" 
                                Text="Delete" CssClass="gridActionbutton"  OnClientClick="return confirm('Are you sure you want to delete this Delegate Information?')" >
                    </asp:Button>
                </ItemTemplate>
                <EditItemTemplate>
                    <asp:Button ID="deligvUpdateButton" runat="server" CausesValidation="False" CommandName="Update" 
                                    Text="Update" CssClass="gridActionbutton"></asp:Button>
                    &nbsp;<asp:Button ID="deligvCancelButton" runat="server" CausesValidation="False" CommandName="Cancel" 
                                    Text="Cancel" CssClass="gridActionbutton"></asp:Button>
                </EditItemTemplate>
                <FooterTemplate>
                    <asp:Button ID="deligvAddButton" runat="server" CommandName="Add" Text="Add Delegate" Width="90%" CausesValidation="false" 
                                CssClass="gridActionbutton">
                    </asp:Button>
                </FooterTemplate>
            </asp:TemplateField>
        </Columns>
        <EmptyDataTemplate>
            <tr>
                <th>Recipient ID</th>
                <th>Delegate</th>
                <th>Active</th>
                <th>Action</th>
            </tr>
            <tr> 
                <td colspan="4" style="text-align:center;">
                    No Delegates were found for you. Delegates can be added by clicking the 'Add Delegate' Button.
                </td> 
            </tr>
            <tr>
                <td></td>
                <td>
                    <asp:DropDownList ID="deligvDDLRecipientName" runat="server" ClientIDMode="Static" 
                                        data-placeholder="Choose delegate…" class="chosen-single">
                    </asp:DropDownList>
                </td>
                <td>
                     <asp:DropDownList ID="deligvDDLActiveInsert" runat="server">
                        <asp:ListItem Selected="True">Yes</asp:ListItem>
                        <asp:ListItem>No</asp:ListItem>
                    </asp:DropDownList>
                </td>
                <td>
                    <asp:Button ID="deligvAddButtonEmpty" runat="server" CommandName="Add" Text="Add Delegate" Width="90%" CausesValidation="false" 
                        CssClass="gridActionbutton">
                    </asp:Button>
                </td>
            </tr>
        </EmptyDataTemplate>
     </asp:GridView>

​

这是我的DataBound事件：

 protected void DelegateInfoGridView_DataBound(object sender, EventArgs e)
    {
        try
        {

            m_strUserID = CommonMethods.ParseUserID(User.Identity.Name);

            //Get the Footer controls that have the new entry data
            Control tFooterControls = getFooterControls(DelegateInfoGridView);
            DropDownList ddlRecipientNames = tFooterControls.FindControl("deligvDDLRecipientName") as DropDownList;              
            m_strXmlTableData = m_pagingClient.GetAllPossibleDelegates(m_strUserID);
            DataTable tdtAllDelegates = CommonMethods.ParseXML(m_strXmlTableData);
            ddlRecipientNames.DataSource = tdtAllDelegates;
            ddlRecipientNames.DataTextField = "RecipientName";
            ddlRecipientNames.DataValueField = "RecipientID";
            ddlRecipientNames.DataBind();
            ddlRecipientNames.Items.Insert(0, new ListItem("", "0"));//This is needed for the jquery-chosen dropdown to add data-holder text
        }
        catch (Exception ex)
        {
            //TO DO: Response.Redirect("~/Error.aspx");
        }
    }

为什么下拉列表在删除所有项目之后不会显示这些项目，但是如果最初在网格视图中没有要显示的项，则将正确显示？我尝试触发所选下拉列表的更新，但在检索数据之前，首先调用它。我不知道代码隐藏中是否存在bug，或者是否需要在javascript中添加一些内容。

谢谢。

更新

问题不在于选择的插件。我从DropDown列表中删除了该属性，该属性将其更改为“选择的”样式，问题仍然存在。因此，在用户删除网格中的所有项后，asp:DropDownList将不会填充。但是，如果不使用任何项初始化网格，则将正确填充DropDown。

UPDATE我有一个建议使用'RowDeleted‘事件来绑定下拉列表。然而，这一事件并没有引发。我将事件添加到标记中：

onrowdeleted="DelegateInfoGridView_RowDeleted"

这是从未调用过的事件：

 protected void DelegateInfoGridView_RowDeleted(object sender, GridViewDeletedEventArgs e)
    {
        try
        {
            m_strUserID = CommonMethods.ParseUserID(User.Identity.Name);

            //Get the Footer controls that have the new entry data
            Control tFooterControls = getFooterControls(DelegateInfoGridView);
            DropDownList tddlRecipientNames = tFooterControls.FindControl("deligvDDLRecipientName") as DropDownList;
            m_strXmlTableData = m_pagingClient.GetAllPossibleDelegates(m_strUserID);
            DataTable tdtAllDelegates = CommonMethods.ParseXML(m_strXmlTableData);
            tddlRecipientNames.DataSource = tdtAllDelegates;
            tddlRecipientNames.DataTextField = "RecipientName";
            tddlRecipientNames.DataValueField = "RecipientID";
            tddlRecipientNames.DataBind();
            tddlRecipientNames.Items.Insert(0, new ListItem("", "0"));//This is needed for the jquery-chosen dropdown to add data-holder text
        }
        catch (Exception ex)
        {
            //TO DO: Response.Redirect("~/Error.aspx");
        }
    }

RowDeleted事件的不同之处在于它不会触发？

Answer 1

问题是，我正在检查FooterControl是否为空。如果是的话，我得到了EmptyTemplateData控件。删除所有行时，FooterControl不是null，但它需要获得EmptyTemplateData控件。因此，我更改了逻辑，以检查Grid >0，而不是空FooterControl。解决了问题..。