Question

I am using itextsharp to populate my PDFs. I have no issues with this. Basically what I am doing is getting the PDF and populating the fields in memory then passing back the MemoryStream to be displayed on a webpage. All this is working with a single document PDF.

What I am trying to figure out now, is merging multiple PDFs into one MemoryStream. The part I cant figure out is, the documents I am populating are identical. So for example, I have a List<Person> that contains 5 persons. I want to fill out a PDF for each person and merge them all into one, in memory. Bare in mind I am going to fill out the same type of document for each person.

The problem I am getting is that when I try to add a second copy of the same PDF to be filled out for the second iteration, it just overwrites the first populated PDF, since it’s the same document, therefore not adding a second copy for the second Person at all.

So basically if I had the 5 people, I would end up with a single page with the data of the 5th person, instead of a PDF with 5 like pages that contain the data of each person respectively.

Here’s some code…

MemoryStream ms = ms = new MemoryStream();
PdfReader docReader = null;
PdfStamper Stamper = null;
List<Person> persons = new List<Person>() {
   new Person("Larry", "David"),
   new Person("Dustin", "Byfuglien"),
   new Person("Patrick", "Kane"),
   new Person("Johnathan", "Toews"),
   new Person("Marian", "Hossa")
};

try
{
   // Iterate thru all persons and populate a PDF for each
   foreach(var person in persons){
      PdfCopyFields Copier = new PdfCopyFields(ms);
      Copier.AddDocument(GetReader("Person.pdf"));
      Copier.Close();

      docReader = new PdfReader(ms.ToArray());
      Stamper = new PdfStamper(docReader, ms);
      AcroFields Fields = Stamper.AcroFields;
      Fields.SetField("FirstName", person.FirstName);
   }
}catch(Exception e){
  // handle error
}finally{
   if (Stamper != null)
   {
      Stamper.Close();
   }
   if (docReader != null)
   {
      docReader.Close();
   }
}

Answer 1

I have created a working solution, I hope this helps someone along the way.

Create a PopulatePDF() method that takes the Person object and returns a byte[]:

private byte[] PopulatePersonPDF(Person obj)
{
   MemoryStream ms = new MemoryStream();
   PdfStamper Stamper = null;

   try
   {
      PdfCopyFields Copier = new PdfCopyFields(ms);
      Copier.AddDocument(GetReader("Person.pdf"));
      Copier.Close();

      PdfReader docReader = new PdfReader(ms.ToArray());
      ms = new MemoryStream();
      Stamper = new PdfStamper(docReader, ms);
      AcroFields Fields = Stamper.AcroFields;
      Fields.SetField("FirstName", obj.FirstName);
   }
   finally
   {
      if (Stamper != null)
      {
         Stamper.Close();
      }
   }
   return ms.ToArray();
}

Create a MergePDFs() method that returns the MemoryStream:

private MemoryStream MergePDFs(List<byte[]> pdfs)
{
   MemoryStream ms = new MemoryStream();
   PdfCopyFields Copier = new PdfCopyFields(ms);

   foreach (var pdf in pdfs)
      Copier.AddDocument(new PdfReader(pdf));
   Copier.Close();
   return ms;
}

Example Implementation:

List<Person> persons = new List<Person>() {
   new Person("Larry", "David"),
   new Person("Dustin", "Byfuglien"),
   new Person("Patrick", "Kane"),
   new Person("Johnathan", "Toews"),
   new Person("Marian", "Hossa")
};

List<byte[]> pdfs = new List<byte[]>();

foreach(var person in persons)
   pdfs.Add(PopulatePersonPDF(person));

MemoryStream ms = MergePDFs(pdfs);