Question

我已经写出以下代码来处理Gridview.RowCommand上应该发生的文件下载。它适用于我使用它的其他地方（在gridview或类似控件之外的linkbutton）。

此Gridview位于UpdatePanel内。

Protected Sub gvBikeInsurance_RowDataBound(sender As Object, e As GridViewRowEventArgs) Handles gvBikeInsurance.RowDataBound
    If e.Row.RowType = DataControlRowType.DataRow Then
        Dim ibtnExportToPDF As ImageButton = TryCast(e.Row.FindControl("ibtnExportToPDF"), ImageButton)
        ScriptManager.GetCurrent(Me).RegisterPostBackControl(ibtnExportToPDF)

        Dim btnDelete As LinkButton = TryCast(e.Row.Cells(e.Row.Cells.Count - 1).Controls(0), LinkButton)
        btnDelete.OnClientClick = "return confirm('Are you sure you want to delete this insurance item');"
    End If
End Sub

Protected Sub gvBikeInsurance_RowCommand(sender As Object, e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles gvBikeInsurance.RowCommand

    Select Case e.CommandName
        Case "PDFExport"
            exportPolicy(e.CommandArgument)
    End Select
End Sub

Private Sub exportPolicy(ByVal BikeInsuranceID As Integer)
    Dim args As New List(Of MySqlParameter)
    args.Add(New MySqlParameter("xbikeinsuranceid", MySqlDbType.Int32))
    args(args.Count - 1).Value = BikeInsuranceID

    Dim dr As MySqlDataReader = db.execDB("InsuranceFiles_Select", CommandType.StoredProcedure, args.ToArray(), GeneralFunctions.ReturnType.DataReader, False)

    Dim output() As Byte
    If dr.HasRows Then
        dr.Read()
        output = dr("filedata")
    End If
    dr.Close()

    Dim outputstr As String = Text.Encoding.ASCII.GetString(output)

    Response.Clear()
    Response.ClearHeaders()
    Response.ContentType = "application/pdf"
    Response.AddHeader("Content-Disposition", String.Format("attachment;filename={0}", "Policy Schedule.pdf"))

    HtmlToPdf.ConvertHtml(outputstr, Response.OutputStream)

    Response.End()
End Sub

系统从表单中捕获用户信息并使用它编写HTML。此HTML用于创建PDF文件，然后自动下载。

问题是该文件似乎没有下载，除非我一步一步地通过调试器运行它。标准执行只显示UpdateProgress内容，该内容会在一段时间后消失。

这里的代码有什么问题吗？最具体地说，在RowDataBound和RowCommand例程以及Response的生成中。

非常感谢任何帮助。

编辑

刚刚在Chrome的控制台中发现了这个错误：

未捕获的Sys.WebForms.PageRequestManagerParserErrorException：Sys.WebForms.PageRequestManagerParserErrorException：无法解析从服务器收到的消息。

Answer 1

事实证明，虽然可能不是最佳实践（我会让更多经验丰富的开发人员对此提出质疑），但我的代码确实有效。

至少它可以工作，如果我在我的RowDataBound子上注册回发控件时使用ToolkitScriptManager而不是ScriptManager：

Protected Sub gvBikeInsurance_RowDataBound(sender As Object, e As GridViewRowEventArgs) Handles gvBikeInsurance.RowDataBound
    If e.Row.RowType = DataControlRowType.DataRow Then
        Dim ibtnExportToPDF As ImageButton = TryCast(e.Row.FindControl("ibtnExportToPDF"), ImageButton)
        ToolkitScriptManager.GetCurrent(Me).RegisterPostBackControl(ibtnExportToPDF)

        Dim btnDelete As LinkButton = TryCast(e.Row.Cells(e.Row.Cells.Count - 1).Controls(0), LinkButton)
        btnDelete.OnClientClick = "return confirm('Are you sure you want to delete this insurance item');"
    End If
End Sub

当您将其添加到页面/母版页时，您将决定使用哪个。请注意，如果您使用的是AJAX Control Tookit .NET 3.5中的控件，则必须使用ToolkitScriptManager

供参考，ScriptManager and ToolkitScriptManager

之间的差异

Answer 2

我相信这是因为您的应用程序正在尝试在updatePanel中使用Response方法。这将失败有几个原因： http://weblogs.asp.net/leftslipper/archive/2007/02/26/sys-webforms-pagerequestmanagerparsererrorexception-what-it-is-and-how-to-avoid-it.aspx

最值得注意的是，在您的示例中，这是由于更新面板。

相反，您可以让更新面板打开一个开始下载的页面，如下所示：

Private Sub exportPolicy(ByVal BikeInsuranceID As Integer)

 'store what you need to create the file in session variables
 Session("fileName") = foundAttachment.FileName
 Session("documentType") = foundAttachment.DocumentType
 Session("byteArray") = byteArray



'this registers a Javascipt function with the page.  You need to create a page Called "Download.aspx"
 ScriptManager.RegisterStartupScript(Me.UpdatePanel1, Me.GetType, "ShowPopup", "window.open('DownloadPage.aspx');", True)
End Sub

现在，在您的DownloadPage.Aspx页面中：

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If (Not IsPostBack) Then
        Dim fileName As String = Session("fileName")
        Dim docType As String = Session("documentType")
        Dim byteArray() As Byte = Session("byteArray")


        If (byteArray.Length > 0) Then
            Dim ms As MemoryStream = New MemoryStream(byteArray)
            Dim sw As StreamWriter = New StreamWriter(ms)

            Response.Clear()
            Response.AddHeader("Content-Disposition", "attachment; filename=" & fileName)
            Response.ContentType = docType
            Response.BinaryWrite(byteArray)
            Response.End()
            Response.Flush()
        End If

    End If
End Sub

在我的示例中，我使用byteArrays来创建文件，但您可以使用您需要的任何方法。

从gridview rowcommand下载文件

2 个答案: