使用memorystream使用VB.NET和Webforms进行pdf下载

Question

I have a method that I wrote that calls a ReportServer and returns a byte array of a pdf of the report. This works. I know because I've used the same method to write a pdf to a file and save it locally. Here I want to write the file to a memory stream and offer it as a download.

    Try
        Dim ms As MemoryStream = New MemoryStream(report, 0, report.Length)
        ms.Position = 0

        Response.Clear()
        Response.Expires = 0
        Response.Buffer = True
        Response.AddHeader("Content-disposition", "attachment;filename=UserReport.pdf")
        Response.ContentType = "application/pdf"
        'ms.WriteTo(Response.OutputStream)
        Response.BinaryWrite(ms.ToArray())
        Response.End()
        HttpContext.Current.ApplicationInstance.CompleteRequest()
        'Response.Flush()

    Catch ex As Exception
        lblERRORMSG.Visible = True
        lblERRORMSG.Text = "Darn!" & ex.Message
        Return
    End Try
End Sub`

This code compiles, runs, and I can even set breakpoints that get hit. But when the button is clicked nothing happens.

Answer 1

There is nothing wrong with the code in question. This code was being used with an UpdatePanel made by telerik called a RadAjaxPanel. The default setting for buttons on pages that use this control is that they do NOT post back. The solution was simple. You need to go to the Page_Load Event in you code behind and add the following code:

ScriptManager1.RegisterPostBackControl(btnNameGoesHere)

This will trigger a postback when the button is clicked!