asp.net - ajaxfileupload 不显示“选择文件”对话框

Question

我正在开发一个内部 Web 应用程序，它收集各种图像并将它们自动绘制到更大的图像上。我在使用 Microsoft 的 AJAX 工具包中的 ajaxFileUpload 控件时遇到问题。

在页面中，用户可以选择在文本框中填写 ID 号，然后单击按钮以获取一些文本数据（图像的元数据）并填充几个文本框/下拉列表。用户还可以选择单击按钮从本地系统上传图像以进行处理。ajaxFileUpload 控件位于 UpdatePanel 上。

当用户使用“填充”功能检索元数据然后选择上传图像时，“选择文件”按钮不会触发本地系统上的“打开文件”对话框。

当用户在检索元数据之前首次尝试上传图像时，“选择文件”按钮会弹出“打开文件”对话框以允许用户选择所需的文件。

ajaxFileUpload 控件在第一种情况下按预期工作；我假设如果我真的可以选择要上传的文件，那么该过程的其余部分将起作用。

需要发布什么代码来尝试解决这个问题？ASPX? 后端VB？

标记：

<asp:UpdatePanel runat = "server" ID = "upMain" >
    <ContentTemplate>
        <asp:Label runat = "server" ID = "lblImageBuilderTitle" Text = "Image Builder" CssClass = "panelTitle" />
        <asp:Table runat = "server">
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "JTN: " />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:TextBox runat = "server" ID = "tbJTN" /><asp:Button runat = "server" ID = "btnPopulate" Text = "+" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "Job Ref: " />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:TextBox runat = "server" ID = "tbJobRef" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "Customer: " />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:DropDownList runat = "server" ID = "ddlImageBuilderCustomer" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "Type: " />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:DropDownList runat = "server" ID = "ddlImageBuilderType" AutoPostBack = "true" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "Email to Deana: " />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:CheckBox runat = "server" ID = "cbEmailDeana" Checked = "true" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "Email to Amy: " />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:CheckBox runat = "server" ID = "cbEmailAmy" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell HorizontalAlign = "Right" Width = "10%">
                    <asp:Label runat = "server" Text = "Rego Branding: " Visible = "false" />
                </asp:TableCell>
                <asp:TableCell>
                    <asp:CheckBox runat = "server" ID = "cbRegoBranding" Visible = "false" />
                </asp:TableCell>
            </asp:TableRow>
            <asp:TableRow>
                <asp:TableCell ColumnSpan = "2" HorizontalAlign = "Center">
                    <asp:Label runat = "server" Text = "Images: " /><br />
                    <asp:GridView runat = "server" ID = "gvImages" AutoGenerateColumns = "false" AutoGenerateSelectButton = "false">
                        <Columns>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:Label runat = "server" ID = "lblOriginalName" Text = "<%# Bind('original_filename') %>" />
                                </ItemTemplate>
                            </asp:TemplateField>
                            <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:Button runat = "server" ID = "btnRowUp" CommandName = "Reorder" CommandArgument = "Up" />
                                    <asp:Button runat = "server" ID = "btnRowDown" CommandName = "Reorder" CommandArgument = "Down" />
                                </ItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                        <EmptyDataTemplate>No images uploaded.</EmptyDataTemplate>
                    </asp:GridView>
                </asp:TableCell>
            </asp:TableRow>
        </asp:Table>
        <asp:ModalPopupExtender runat = "server" ID = "mpePopulate" TargetControlID = "btnPopulateDummy" PopupControlID = "pnlPopulate" BackgroundCssClass = "modalBackground" />
        <asp:Button runat = "server" ID = "btnPopulateDummy" CssClass = "invisible" />
        <asp:ModalPopupExtender runat = "server" ID = "mpeUpload" TargetControlID = "btnUpload" PopupControlID = "pnlUpload" CancelControlID = "btnUploadClose" BackgroundCssClass = "modalBackground" />
        <asp:Button runat = "server" ID = "btnUpload" Text = "Upload Images" />
    </ContentTemplate>
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID = "gvPopulate" EventName = "SelectedIndexChanged" />
        <asp:AsyncPostBackTrigger ControlID = "btnUploadClose" EventName = "Click" />
        <asp:AsyncPostBackTrigger ControlID = "gvImages" EventName = "DataBound" />
        <asp:AsyncPostBackTrigger ControlID = "ajuImageUpload" EventName = "UploadComplete" />
    </Triggers>
</asp:UpdatePanel>

代码隐藏：

Private Sub ImageBuilder_PreRender(sender As Object, e As System.EventArgs) Handles Me.PreRender
    Dim dtIBImages As New DataTable
    If IsPostBack = False Then
        BindCustomerDDL("ImageBuilder")
        BindCategoryDDL("ImageBuilder")
        BindTemplatesDDL()
        'Session("dtIBImages") = Nothing

        'dtIBImages.Columns.Add("id")
        'dtIBImages.Columns.Add("original_filename")
        'dtIBImages.Columns.Add("image_filename")
        'dtIBImages.Columns.Add("disposition")

        '    Session("dtIBImages") = dtIBImages
    Else
        dtIBImages = Session("dtIBImages")
        gvImages.DataSource = dtIBImages
        gvImages.DataBind()
    End If
    dtIBImages = Session("dtIBImages")
    gvImages.DataSource = dtIBImages
    gvImages.DataBind()
End Sub