iTextSharp filling forms and creating multiple pages - vb.net

Question

I have following written codes
Dim template As String = Server.MapPath("files/") & "2_paged_form.pdf"
Dim newFile As String = Server.MapPath("exports/") & "newFile.pdf"
Dim reader = New PdfReader(template)
Dim output = New FileStream(newFile, FileMode.Create, FileAccess.Write)
Dim stamp = New PdfStamper(reader, output)
stamp.AcroFields.SetField("client", "hello")
stamp.AcroFields.SetField("name", "test test")
stamp.AcroFields.SetField("address", "Hellocourt")
stamp.AcroFields.SetField("postcode", "xx 3xx")
stamp.AcroFields.SetField("dob", "11/02/1987")
stamp.FormFlattening = True
stamp.Close()
output.Close()
reader.Close()
I have managed to created a newfile.pdf with only onetime entry from 2_paged_form.pdf.
However I have multiple information to loop through so that newfile.pdf has multiple entries. for example newfile.pdf should have 10 pages with 5 different entries.
Could anyone help?

Answer 1

This is documented on the official iText site and in the book.
If you prefer watching a video, you can watch this tutorial. You can try the examples here. You need the entry "Fill, Flatten and Merge: how to do it correctly." The code for these examples can be found here: FillFlattenMerge2. Note that there's also a FillFlattenMerge1 example that demonstrates how NOT to do it. Please don't use that example ;-)
If you prefer reading a book, please download Chapter 6 of "iText in Action - Second Edition". You already know how to fill out one form (as described on page 185), you now want to merge different results. Again, there's an example on how not to do it (on page 190) and on how you should do it (on page 190-191).
I have never written a line of vb.net, but please look at this Java code as if it were pseudo code:
PdfCopy copy = new PdfSmartCopy(document, new FileOutputStream(dest));
document.open();
ByteArrayOutputStream baos;
PdfReader reader;
PdfStamper stamper;
AcroFields fields;
while (data.hasMoreElements()) {
// create a PDF in memory
baos = new ByteArrayOutputStream();
reader = new PdfReader(SRC);
stamper = new PdfStamper(reader, baos);
fields = stamper.getAcroFields();
MyData myData = data.nextElement();
fields.setField("name", myData.getName());
fields.setField("address", myData.getAddress());
...
stamper.setFormFlattening(true);
stamper.close();
reader.close();
// add the PDF to PdfCopy
reader = new PdfReader(baos.toByteArray());
copy.addDocument(reader);
reader.close();
}
document.close();
As you can see, you need to create to fill the form resulting in a PDF that is kept in memory. Then you need to read this PDF from memory and add it to a PdfSmartCopy instance using the addDocument() method.
P.S. 1: What is wrong with the bad example? It results in bloated PDFs because the static content of the form is added redundantly as many times as you copy the form. PdfSmartCopy checks for redundant information and will add the static content only once.
P.S. 2: Why is there a bad way of doing it? The bad way of doing it, is actually a good way if the documents you are merging are all very different. In this case, the bad way is much faster and less memory-extensive and therefore actually the good way. It's only bad when you're merging documents that are very similar to each other, such as the same form filled out with different data sets.