ItextSharp - Acrofields are empty

问题:

I have a PDF form with filled out fields. If I try to read the acrofields they are empty. But in the PDF I can change the values and save them.

private static string GetFormFieldNamesWithValues(PdfReader pdfReader)
{
    return string.Join("\r\n", pdfReader.AcroFields.Fields
                                   .Select(x => x.Key + "=" +
                                    pdfReader.AcroFields.GetField(x.Key))
                                   .ToArray());
}

var reader = new PdfReader((DataContext as PDFContext).Datei);
AcroFields form = reader.AcroFields;
txt.Text = GetFormFieldNamesWithValues(reader);

How to read the fields?

回答1:

Clearly your PDF is broken. The fields are defined as widget annotations on the page level, but they aren't referenced in the /AcroForm fields set on the document root level.

You can fix your PDF using the FixBrokenForm code sample:

PdfReader reader = new PdfReader(src);
PdfDictionary root = reader.getCatalog();
PdfDictionary form = root.getAsDict(PdfName.ACROFORM);
PdfArray fields = form.getAsArray(PdfName.FIELDS);

PdfDictionary page;
PdfArray annots;
for (int i = 1; i <= reader.getNumberOfPages(); i++) {
    page = reader.getPageN(i);
    annots = page.getAsArray(PdfName.ANNOTS);
    for (int j = 0; j < annots.size(); j++) {
        fields.add(annots.getAsIndirectObject(j));
    }
}
PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest));
stamper.close();
reader.close();

You should inform the creators of the tool that was used to produce the form that their PDFs aren't compliant with the PDF reference.

回答2:

Here is my c#-Code:

   PdfReader reader = new PdfReader(src);
        PdfDictionary root = reader.Catalog;
        PdfDictionary form = root.GetAsDict(PdfName.ACROFORM);
        PdfArray fields = form.GetAsArray(PdfName.FIELDS);

        PdfDictionary page;
        PdfArray annots;
        for (int i = 1; i <= reader.NumberOfPages; i++)
        {
            page = reader.GetPageN(i);
            annots = page.GetAsArray(PdfName.ANNOTS);
            for (int j = 0; j < annots.Size; j++)
            {
                fields.Add(annots.GetAsIndirectObject(j));
            }
        }
        PdfStamper stamper = new PdfStamper(reader, new FileStream(dest, FileMode.Create));
        stamper.Close();
        reader.Close();

回答3:

C# version

    public void FixBrokenForm(string src, string dest)
    {
        PdfReader reader = new PdfReader(src);
        PdfDictionary root = reader.Catalog;
        PdfDictionary form = root.GetAsDict(PdfName.ACROFORM);
        PdfArray fields = form.GetAsArray(PdfName.FIELDS);

        PdfDictionary page;
        PdfArray annots;
        for (int i = 1; i <= reader.NumberOfPages; i++)
        {
            page = reader.GetPageN(i);
            annots = page.GetAsArray(PdfName.ANNOTS);
            for (int j = 0; j < annots.Length; j++)
            {
                fields.Add(annots.GetAsIndirectObject(j));
            }
        }
        PdfStamper stamper = new PdfStamper(reader, new FileStream(dest, FileMode.Create));
        stamper.Close();
        reader.Close();
      }

You will need Itextsharp to make the above code work.