PDFSharp filling in form fields

c# pdf pdfsharp
user770344 picture user770344 · Jun 5, 2011 · Viewed 30.4k times · Source

I would like to fill in form fields in a premade PDF doc, but I'm receiving a Null Refrence error with AcroForm when running.

 string fileN4 = TextBox1.Text + " LOG.pdf";

  File.Copy(Path.Combine(textBox4.Text + "\\", fileN4),
               Path.Combine(Directory.GetCurrentDirectory(), fileN4), true);

  // Open the file
  PdfDocument document = PdfReader.Open(fileN4, PdfDocumentOpenMode.Modify);

  PdfTextField currentField = (PdfTextField)(document.AcroForm.Fields["<CASENUM>"]);
  //const 
        string caseName = TextBox1.Text;
  PdfString caseNamePdfStr = new PdfString(caseName);

  //set the value of this field
  currentField.Value = caseNamePdfStr;


  // Save the document...
  document.Save(fileN4);

So PdfTextField currentField = (PdfTextField)(document.AcroForm.Fields["<CASENUM>"]); is where the error happens. It seams that AcroForm is not even recognizing the fields.

Another option would be a find and replace text in a PDF (without using itextsharp as cannot use due to licensing).

Any help would be awesome!

Answer

Marc Ferree picture Marc Ferree · Aug 28, 2012

You also need this if you are attempting to populate PDF form fields, you also need to set the NeedsAppearances element to true. Otherwise the PDF will "hide" the values on the form. Here is the VB code.

If objPdfSharpDocument.AcroForm.Elements.ContainsKey("/NeedAppearances") = False Then
    objPdfSharpDocument.AcroForm.Elements.Add("/NeedAppearances", New PdfSharp.Pdf.PdfBoolean(True))
Else
    objPdfSharpDocument.AcroForm.Elements("/NeedAppearances") = New PdfSharp.Pdf.PdfBoolean(True)
End If

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