Concat two PDFs in Firebase Cloud Functions with pdf-lib - node.js

Question

I'm trying to merge 2 pdf files using pdf-lib (I got the example of code from the official site of pdf-lib). The goal is to trigger the cloud function when new file is uploaded to bucket. The function then collect urls of files to be merged in the same bucket with the new one. I am able to get urls but I have an error in pdf-lib. Maybe I'm importing it the wrong way. Because in example it is in ES6 syntax (import) but nodejs needs require. I'm new to backed and nodejs. So any help is highly appreciated.
const functions = require('firebase-functions');
const { Storage } = require('#google-cloud/storage');
const storage = new Storage();
const admin = require('firebase-admin');
admin.initializeApp();
const { PDFDocument } = require('pdf-lib');
const fetch = require('node-fetch');
exports.testCloudFunc = functions.storage.object().onFinalize(async object => {
const filePath = object.name;
const { Logging } = require('#google-cloud/logging');
console.log(`Logged: FILEPATH: ${filePath}`);
const id = filePath.split('/');
console.log(`Logged: ID: ${id[0]}/${id[1]}`);
const bucket = object.bucket;
console.log(`Logged: BUCKET: ${object.bucket}`);
async function listFilesByPrefix() {
const options = {
prefix: id[0] + '/' + id[1]
};
const [files] = await storage.bucket(bucket).getFiles(options);
const endFiles = files.filter(el => {
return (
el.name === id[0] + '/' + id[1] + '/' + 'invoiceReport.pdf' ||
el.name === id[0] + '/' + id[1] + '/' + 'POD.pdf' ||
el.name === id[0] + '/' + id[1] + '/' + 'rateConfirmation.pdf'
);
});
endFiles.forEach(el => console.log(el.name));
const promises = [];
for (let i = 0; i < endFiles.length; i++) {
console.log(endFiles[i].name);
promises.push(
endFiles[i].getSignedUrl({
action: 'read',
expires: '03-17-2025'
})
);
}
const urlsArray = await Promise.all(promises);
return urlsArray;
}
listFilesByPrefix()
.then(results => {
results.forEach(el => console.log(el));
copyPages(results[0], results[1]);
return results;
})
.catch(console.error);
});
async function copyPages(url1, url2) {
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();
}
But in firebase cloud console logs I'm getting this:
TypeError: Cannot read property 'node' of undefined
at PDFDocument.<anonymous> (/srv/node_modules/pdf-lib/cjs/api/PDFDocument.js:459:62)
at step (/srv/node_modules/tslib/tslib.js:136:27)
at Object.next (/srv/node_modules/tslib/tslib.js:117:57)
at fulfilled (/srv/node_modules/tslib/tslib.js:107:62)
at <anonymous>
at process._tickDomainCallback (internal/process/next_tick.js:229:7)

Answer 1

I was facing the same problem
Make sure your files are public or generate a signed url
an example follows:
const options = {
prefix: 'notas', //folder name
};
const optionsBucket = {
version: 'v2',
action: 'read',
expires: Date.now() + 1000 * 60 * 9, // 9 minutes
};
const [files] = await storage.bucket('your-bucket-name').getFiles(options);
const mergedPdf = await PDFDocument.create();
for (let nota of files) {
let fileName = nota.name;
if (fileName.endsWith('.pdf')) {
const [url] = await storage
.bucket(bucketName)
.file(fileName)
.getSignedUrl(optionsBucket); //generate signed url
const arrayBuffer = await fetch(url).then(res => res.arrayBuffer());
const pdf = await PDFDocument.load(arrayBuffer);
const copiedPages = await mergedPdf.copyPages(pdf, pdf.getPageIndices());
copiedPages.forEach((page) => {
mergedPdf.addPage(page);
});
}
const mergedPdfFile = await mergedPdf.save();
const file = bucket.file(`folder/filename.pdf`);
await file.save(
mergedPdfFile
);
}