Principles of Merging PDF and Data with VB.net, and the FDF Toolkit .net component. 

Rules: Make sure when posting PDF Data to a buffer, do not post any HTML along with PDF Data. Remove any header information by declaring "Response.Clear()" before posting any PDF or PDF data MIME content.

Notes: Flattening the pdf form can be set with the true or false switch in the FDFDoc.PDFMergeFDF2Buf function using the FDF Toolkit .net component.

Imports FDFApp
Imports FDFApp.FDFApp_Class
Imports FDFApp.FDFDoc_Class

Public Class loadform
        Inherits System.Web.UI.Page
Private URLPath as String = ""
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    URLPath = Request.Url.ToString
    Try
        Load_FDF()
    Catch Ex as Exception
        Response.Write("Error: " & Ex.Message)
        Response.End
    End Try
End Sub

Public Function Load_FDF()
    ' DECLARE THE COMPONENTS
    Dim FDFApp As New FDFApp.FDFApp_Class
    Dim FDFDoc As New FDFApp.FDFDoc_Class
    ' INITIALIZE THE COMPONENTS
    FDFDoc = FDFApp.FDFCreate
        Response.Clear()
        Response.ContentType = FDFApp.MimePDF

    ' SET TEXT FIELD VALUES
    FDFDoc.FDFSetValue("txtForm_Field1","Field_Value")
    FDFDoc.FDFSetValue("txtForm_Field2","Field_Value")
    FDFDoc.FDFSetValue("txtForm_Field3","Field_Value")

    ' SET OPTION OR LIST FIELD NAMES AND VALUES
    FDFDoc.FDFSetOpt("optForm_Field",New String() _{"Opt_Value01","Opt_Value02","Opt_Value03","Opt_Value04"},New String() _{"DisplayName_01","DisplayName_02","DisplayName_03","DisplayName_04"})
    
    FDFDoc.FDFSetValues("optForm_Field",New String(){"Opt_Value02","Opt_Value03")
    'FDFDoc.FDFSetValue("optForm_Field","Opt_Value02")
    
    ' SET PDF LOCATION
    FDFDoc.FDFSetFile(URLPath & "PDFs/sample.pdf")
    ' MERGE PDF WITH FDF DATA AND FLATTEN
    FDFDoc.PDFData = FDFDoc.PDFMergeFDF2Buf(FDFDoc, True)     ' WRITE THE FDF TO THE BUFFER
    Response.BinaryWrite(FDFDoc.PDFData)

    ' BROWSER READS THE PDF DOCUMENT AND ADOBE PLUG-IN OPENS
    '
End Function

End Class 

Principles to Loading a PDF with Data with ASP.net

Rules: Make sure when posting FDF Data to a buffer, do not post any HTML along with FDF Data, using VB.net, ASP.net, and the FDF Toolkit .net component. Remove any header information by declaring "Response.Clear()" before posting any PDF or PDF data MIME content.

Imports FDFApp
Imports FDFApp.FDFApp_Class
Imports FDFApp.FDFDoc_Class

Public Class loadform
        Inherits System.Web.UI.Page
Private URLPath as String = ""
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    URLPath = Request.Url.ToString
    Try
        Load_FDF()
    Catch Ex as Exception
        Response.Write("Error: " & Ex.Message)
        Response.End
    End Try
End Sub

Public Function Load_FDF()
    ' DECLARE THE COMPONENTS
    Dim FDFApp As New FDFApp.FDFApp_Class
    Dim FDFDoc As New FDFApp.FDFDoc_Class
    ' INITIALIZE THE COMPONENTS
    FDFDoc = FDFApp.FDFCreate
Response.Clear()
Response.ContentType = FDFApp.MimeFDF

    ' SET TEXT FIELD VALUES
    FDFDoc.FDFSetValue("txtForm_Field1","Field_Value")
    FDFDoc.FDFSetValue("txtForm_Field2","Field_Value")
    FDFDoc.FDFSetValue("txtForm_Field3","Field_Value")

    ' SET OPTION OR LIST FIELD NAMES AND VALUES
    FDFDoc.FDFSetOpt("lstForm_Field",New String() _{"lst_Value01","lst_Value02","lst_Value03","lst_Value04"},New String() _{"DisplayName_01","DisplayName_02","DisplayName_03","DisplayName_04"})
    
    FDFDoc.FDFSetValues("lstForm_Field",New String(){"lst_Value02","lst_Value03")
    'FDFDoc.FDFSetValue("lst_Form_Field","lst_Value02")
    
    ' SET PDF LOCATION
    FDFDoc.FDFSetFile(URLPath & "PDFs/sample.pdf")

    ' WRITE THE FDF TO THE BUFFER
    Response.BinaryWrite(FDFDoc.FDFSavetoBuf(FDFApp.FDFType.FDF, False))

    ' BROWSER READS THE FDF DATA AND ADOBE PLUG-IN MERGES PDF WITH FDF DATA
    '
End Function

End Class 

BASIC PDF PROGRAMMING PRINCIPLES - MICROSOFT .NET VERSION

Principles of Merging Adobe Acrobat PDF Form and data, and forcing the web browser to save the file with VB.net

Rules: Make sure when posting PDF Data to a buffer, do not post any HTML along with PDF Data. Remove any header information except for the declaration of the code behind or remove everything below the first line of the .ASPX web page. Also, PDF MIME has to be setup on the web server.

Notes: Flattening the pdf form can be set with the true or false switch in the FDFDoc.PDFMergeFDF2Buf function.

Imports FDFApp
Imports FDFApp.FDFApp_Class
Imports FDFApp.FDFDoc_Class

Public Class loadform
        Inherits System.Web.UI.Page
Private URLPath as String = ""
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    URLPath = Request.Url.ToString
    Try
        DownloadFile(Export_PDF_Flattened)
    Catch Ex as Exception
        Response.Write("Error: " & Ex.Message)
        Response.End
    End Try
End Sub

Sub DownloadFile(ByVal xFile As Byte())
    Try
          Dim FileName As String = "PDFFile.pdf"
            If xFile.Length > 0 Then
                Response.Clear()
                Response.ContentType = "application/pdf"
                'Response.ContentType = "application/octet-stream";
                Response.AppendHeader("Content-Disposition", "attachment; filename=""" & FileName & """")
                Response.BinaryWrite(xFile)
                Response.Flush()
            End If
        Catch ex As Exception
                Response.Write("Error: " & Ex.Message)
                Response.End
        End Try
End Sub

Public Function Export_PDF_Flattened() As Byte()
        Try
            Dim FDFApp As New FDFApp.FDFApp_Class
            Dim FDFDoc As New FDFApp.FDFDoc_Class
            FDFDoc = FDFApp.FDFCreate
            FDFDoc = Load_FDF(FDFDoc)
            FDFDoc.PDFData = FDFDoc.PDFMergeFDF2Buf(FDFDoc, True)
            Return FDFDoc.PDFData
        Catch ex As Exception
                Response.Write("Error: " & Ex.Message)
                Response.End
        End Try
End Function

Public Function Load_FDF(FDFDoc As FDFApp.FDFDoc_Class) As FDFApp.FDFDoc_Class
    ' INITIALIZE THE COMPONENTS
    FDFDoc = FDFApp.FDFCreate
        Response.Clear()
        Response.ContentType = FDFApp.MimePDF

    ' SET TEXT, CHECKBOX, AND OPTION FIELD VALUES
    FDFDoc.FDFSetValue("txtForm_Field1","Field_Value1")
    FDFDoc.FDFSetValue("chkForm_Field2","Field_Value2")
    FDFDoc.FDFSetValue("optForm_Field3","Field_Value3")
    ' SET LIST FIELD NAME ,DISPLAY NAME, AND VALUES
    FDFDoc.FDFSetOpt("lstForm_Field",New String() _{"lst_Value01","lst_Value02","lst_Value03","lst_Value04"},New String() _{"DisplayName_01","DisplayName_02","DisplayName_03","DisplayName_04"})
    'FDFDoc.FDFSetValues("lstForm_Field",New String(){"lst_Value02","lst_Value03")
    'FDFDoc.FDFSetValue("lstForm_Field","lst_Value02")
    
    ' SET PDF LOCATION
    FDFDoc.FDFSetFile(URLPath & "PDFs/sample.pdf")

    Return FDFDoc
End Function

End Class