FilestreamResult not opening - asp.net-mvc

Question

I have these two methods in my controller.I want to open the FilestreamResult pdf() that returns a file stream result.However, i am getting OutputStream is not available when a custom TextWriter is used error.I am using itextsharp for pdf.
Here is my code :
public FileStreamResult pdf()
{
MemoryStream workStream = new MemoryStream();
Document document = new Document();
PdfWriter.GetInstance(document, workStream).CloseStream = false;
List<Plant> plants = new List<Plant>();
foreach (var item in context.Plants)
{
plants.Add(item);
}
byte[] byteInfo = GeneratePdf(plants);
workStream.Write(byteInfo, 0, byteInfo.Length);
workStream.Position = 0;
return new FileStreamResult(workStream, "application/pdf");
}
and the Generate pdf method is
private static byte[] GeneratePdf(List<Plant> plants)
{
using (MemoryStream memoryStream = new MemoryStream())
{
using (var doc = new Document())
{
PdfWriter.GetInstance(doc, memoryStream);
doc.Open();
doc.SetMargins(120, 120, 270, 270);
BaseFont font = BaseFont.CreateFont(BaseFont.TIMES_ROMAN, BaseFont.CP1252, false);
Font normalFont = new Font(font, 12, Font.NORMAL, BaseColor.BLACK);
Paragraph pgTitle = new Paragraph();
pgTitle.Font = new Font(font, 20, Font.NORMAL, BaseColor.BLACK);
pgTitle.Add("American University of Beirut");
doc.Add(pgTitle);
Paragraph pgPlantTitle = new Paragraph();
pgPlantTitle.Font = new Font(font, 18, Font.NORMAL, BaseColor.BLACK);
pgPlantTitle.Add("Plant Description");
doc.Add(pgPlantTitle);
foreach (Plant p in plants)
{
Paragraph plantDisc = new Paragraph();
plantDisc.Font = new Font(font, 14, Font.NORMAL, BaseColor.BLACK);
plantDisc.Add(p.ScientificName);
plantDisc.Add(p.TypeOfPlants.ToString());
plantDisc.Add(p.PlantHeightRanges.ToString());
plantDisc.Add(p.PlantSpreadRanges.ToString());
plantDisc.Add(p.PlantShapes.ToString());
plantDisc.Add(p.NativeOrigin);
plantDisc.Add(p.Colors.ToString());
plantDisc.Add(p.Colors1.ToString());
plantDisc.Add(p.LightRequirements.ToString());
plantDisc.Add(p.WaterRequirements.ToString());
doc.Add(plantDisc);
doc.Add(new Paragraph(" "));
}
doc.Close();
memoryStream.Close();
return memoryStream.ToArray();
}
}
}
Any help?

Answer 1

You're using the Document and PdfWriter classes incorrectly in your first method. I'm going to throw some comments into that method to better explain what's going on.
public FileStreamResult pdf()
{
//Create a generic Stream for someone to write their bytes to
MemoryStream workStream = new MemoryStream();
//Create an iText Document helper object which is a friendly way to create new PDFs using things like tables and paragraphs.
//No where in the code below will this helper object be used so that's the first problem.
Document document = new Document();
//Bind our document helper and stream to a PdfWriter.
//This writer will _exclusively own_ the Stream from now on.
//If _anyone_ else writes to the stream (as you are doing below) it will break the PDF or possibly just throw an exception
PdfWriter.GetInstance(document, workStream).CloseStream = false;
//Business logic here unrelated to the problem
List<Plant> plants = new List<Plant>();
foreach (var item in context.Plants)
{
plants.Add(item);
}
//Create a byte array that represents a PDF. The GeneratePdf appears to be correct.
byte[] byteInfo = GeneratePdf(plants);
//Even though we declared above that we want our PdfWriter to have exclusive access to the Stream,
//ignore that and write our byte array to it.
workStream.Write(byteInfo, 0, byteInfo.Length);
//Rewind the stream
workStream.Position = 0;
return new FileStreamResult(workStream, "application/pdf");
}
Hopefully those comments make sense. Your GeneratePdf() method is what makes a PDF. Once you have a valid PDF, unless you want to modify it or inspect it you no longer have any need for iTextSharp. So your first method should be changed to something like the below. (I don't have VS available right now but this should probably compile except for a possible typo or two.)
//Business logic
List<Plant> plants = new List<Plant>();
foreach (var item in context.Plants)
{
plants.Add(item);
}
//Create our PDF
byte[] byteInfo = GeneratePdf(plants);
//Wrap the bytes in a Stream and return
using( var workStream = new MemoryStream( byteInfo ) )
{
return new FileStreamResult(workStream, "application/pdf");
}

Answer 2

The way you've described the Exception, am making an educated guess that your problem is in a view linking to your controller/action. For example if you have a View and are creating a hyperlink like the commented section:
#* remove comment to see Exception
<h2>Exception: "OutputStream is not available when a custom TextWriter is used."</h2>
<p>
This throws an Exception
</p>
*#
<h2>Correct!</h2>
<p>
<a href="#Url.Action("IndexPdf")" target='_blank'>This works!</a>
</p>
The exact Exception you describe is thrown:
System.Web.HttpException: OutputStream is not available when a custom
TextWriter is used.
So use Url.Action().
Aside from that, a few notes about the GeneratePdf() method in your code:
Remove the Close() calls on MemoryStream and Document, since they're both in using statements.
Move the MemoryStream call to ToArray() outside the Document using block. Otherwise the PDF result may be corrupted.
A shortened example based on your code:
private static byte[] GeneratePdf(List<Plant> plants)
{
using (MemoryStream memoryStream = new MemoryStream())
{
using (var doc = new Document())
{
PdfWriter.GetInstance(doc, memoryStream);
doc.Open();
doc.SetMargins(120, 120, 270, 270);
Paragraph pgTitle = new Paragraph("TEST");
doc.Add(pgTitle);
// initialize title, etc, here
// and iterate over plants here
}
// return **AFTER** Document is disposed
return memoryStream.ToArray();
}
}
And a few notes on your pdf() Action:
Maybe a typo or copy/paste error, but there's no reason for Document or PdfWriter.GetInstance()
If you return a less specific ActionResult instead of the FileStreamResult, you do not have to make an in-memory copy of the PDF. I.e. you can eliminate the MemoryStream, and instead call Controller.File(), since the first parameter is a byte array:
Another shortened example based on your code, this time for the controller action:
public ActionResult IndexPdf()
{
var plants = new List<Plant>();
// get your plants here
byte[] byteInfo = GeneratePdf(plants);
return File(byteInfo, "application/pdf");
}