Copy Pages results form fields disappearing

What were you trying to do?

I was trying to get fields from a multiple-page pdf file I generated with the copyPage paradigm from the documentation. This paradigm is very similar to the example: ` async function copyPages() { const url1 = 'https://pdf-lib.js.org/assets/with_update_sections.pdf' const url2 = 'https://pdf-lib.js.org/assets/with_large_page_count.pdf'

const firstDonorPdfBytes = await fetch(url1).then(res => res.arrayBuffer()) const secondDonorPdfBytes = await fetch(url2).then(res => res.arrayBuffer())

const firstDonorPdfDoc = await PDFDocument.load(firstDonorPdfBytes) const secondDonorPdfDoc = await PDFDocument.load(secondDonorPdfBytes)

const pdfDoc = await PDFDocument.create();

const [firstDonorPage] = await pdfDoc.copyPages(firstDonorPdfDoc, [0]) const [secondDonorPage] = await pdfDoc.copyPages(secondDonorPdfDoc, [742])

pdfDoc.addPage(firstDonorPage) pdfDoc.insertPage(0, secondDonorPage)

const pdfBytes = await pdfDoc.save() } `

So I have 1 pdf I fill out based on some parameters. If there are many parameters, I generate another instance of that PDF and join them together based on the above paradigm.

Later in the life cycle of the joined PDF, I try to write to it again by trying to modify the text within the fields.

How did you attempt to do it?

I attempted to get the form fields from a multiple-page PDF using a few methods, but the main was to just load the multiple-page PDF, get the form, then get the fields.

After trying a few different tactics I settled on this method to diagnose the problem: let pdfDoc = await PDFDocument.load(pdfBytes) const form1 = pdfDoc.getForm() const fields1 = form1.getFields() console.log("FIELDS 1", fields1) let container = []; for(let i = 0; i < pdfDoc.getPages().length; i++){ const subDocument = await PDFDocument.create(); // copy the page at current index const [copiedPage] = await subDocument.copyPages(pdfDoc, [i]) subDocument.addPage(copiedPage); const pdfBytesTemp = await subDocument.save() let tempDoc = await PDFDocument.load(pdfBytesTemp) let form3 = tempDoc.getForm() let fields3 = form3.getFields() console.log("FIELDS3", fields3) container.push(pdfBytesTemp) } console.log("CONTAINER LENGTH", container.length)

This is where pdfBytes is a variable containing the buffer of the PDF pulled from a CDN using Axios.

With this system, I tried to read the fields before splitting up the PDF and then after splitting up a PDF. fields1 didn't log anything and neither did fields3. As a result, I attempted a single-page PDF which does yield results for fields1 to see what would happen.

What actually happened?

What actually happened was that fields3 came back as an empty array, as a result, I concluded copyPages possibly strips out the fields from the original PDF during the copy process.

By extension, this could be a reason why my multiple-page PDFs don't show up with fields as I concatenated the PDFs using the copyPages methodology.

What did you expect to happen?

I expected to see a list of fields after the copyPages method.

How can we reproduce the issue?

The best way to reproduce this is to take the code from the "How did you attempt to do it method?". With this code, one would pass a PDF with form fields generated with adobe acrobat. The console logs are properly placed to notice that the form fields disappear after the copyPages method.

Attached is an example of such a 1-page form that I would concatenate. AOB.pdf

Version

1.16.0

What environment are you running pdf-lib in?

Node

Checklist

• My report includes a Short, Self Contained, Correct (Compilable) Example.
• I have attached all PDFs, images, and other files needed to run my SSCCE.

Additional Notes

Thank you for your time.