How can I merge multiple PDFs to Single PDF in google app script?

Question

I have more than 3 PDF files and I want to merge them into a single PDF using Google App Script, How can I do this?

Answer 1

You can achieve this using pdf.co rest API for merge. Following is source code for your reference.

Source code here is using Google Drive folder to retrieve all PDF files inside, and does merging and saves them back to same folder. However, this can be changed as per our requirement.

/**
 * IMPORTANT: Add Service reference for "Drive". Go to Services > Locate "Drive (drive API)" > Add Reference of it 
 */

// Add Your PDF.co API Key here
const pdfCoAPIKey = 'PDFco_API_Key_Here';

// Get the active spreadsheet and the active sheet
ss = SpreadsheetApp.getActiveSpreadsheet();
ssid = ss.getId();

// Look in the same folder the sheet exists in. For example, if this template is in
// My Drive, it will return all of the files in My Drive.
var ssparents = DriveApp.getFileById(ssid).getParents();

// Store File-Ids/PermissionIds used for merging
let filePermissions = [];

/**
 * Note: Here, we're getting current folder where spreadsheet is residing.
 * But we can certainly pick any folder of our like by using Folder related functions.
 * For example:
  var allFolders = DriveApp.getFoldersByName("Folder_Containing_PDF_Files");
  while (allFolders.hasNext()) {
    var folder = allFolders.next();
    Logger.log(folder.getName());
  }
 */
// Loop through all the files and add the values to the spreadsheet.
var folder = ssparents.next();

/**
 * Add PDF.co Menus in Google Spreadsheet
 */
function onOpen() {
  var menuItems = [
    {name: 'Merge All Files From Current Folder', functionName: 'mergePDFDocumentsFromCurrentFolder'} 
  ];
  ss.addMenu('PDF.co', menuItems);
}

function mergePDFDocumentsFromCurrentFolder(){
  var allFilesLink = getPDFFilesFromCurFolder(pdfCoAPIKey);
  mergePDFDocuments(allFilesLink, pdfCoAPIKey);
}

/**
 * Get all PDF files from current folder
 */
function getPDFFilesFromCurFolder(pdfCoAPIKey) {
  var files = folder.getFiles();
  var allFileUrls = [];

  while (files.hasNext()) {
    var file = files.next();

    var fileName = file.getName();
    if(fileName.endsWith(".pdf")){
      // Create Pre-Signed URL from PDF.co
      var respPresignedUrl = getPDFcoPreSignedURL(fileName, pdfCoAPIKey)

      if(!respPresignedUrl.error){
        var fileData = file.getBlob();
        if(uploadFileToPresignedURL(respPresignedUrl.presignedUrl, fileData, pdfCoAPIKey)){
          // Add Url
          allFileUrls.push(respPresignedUrl.url);
        }
      }
    }
  }

  return allFileUrls.join(",");
}

/**
 * Merges PDF URLs using PDF.co and Save to drive
 */
function mergePDFDocuments(pdfUrl, pdfCoAPIKey) {

  // Get Cells for Input/Output
  let resultUrlCell =  ss.getRange("A4");
  
  // Prepare Payload
  var data = {
    "async": false,
    "encrypt": false,
    "inline": true,
    "name": "result",
    "url": pdfUrl
  };

  // Prepare Request Options
  var options = {
    'method' : 'post',
    'contentType': 'application/json',
    'headers': {
      "x-api-key": pdfCoAPIKey
    },
    // Convert the JavaScript object to a JSON string.
    'payload' : JSON.stringify(data)
  };
  
  // Get Response
  // https://developers.google.com/apps-script/reference/url-fetch
  var pdfCoResponse = UrlFetchApp.fetch('https://api.pdf.co/v1/pdf/merge', options);

  var pdfCoRespContent = pdfCoResponse.getContentText();
  var pdfCoRespJson = JSON.parse(pdfCoRespContent);

  // Display Result
  if(!pdfCoRespJson.error){
    // Upload file to Google Drive
    uploadFile(pdfCoRespJson.url);

    // Update Cell with result URL
    resultUrlCell.setValue(pdfCoRespJson.url);    
  }
  else{
    resultUrlCell.setValue(pdfCoRespJson.message);    
  }
}

/**
 * Gets PDF.co Presigned URL
 */
function getPDFcoPreSignedURL(fileName, pdfCoAPIKey){
  // Prepare Request Options
  var options = {
    'method' : 'GET',
    'contentType': 'application/json',
    'headers': {
      "x-api-key": pdfCoAPIKey
    }
  };

  var apiUrl = `https://api.pdf.co/v1/file/upload/get-presigned-url?name=${fileName}`;
  
  // Get Response
  // https://developers.google.com/apps-script/reference/url-fetch
  var pdfCoResponse = UrlFetchApp.fetch(apiUrl, options);

  var pdfCoRespContent = pdfCoResponse.getContentText();
  var pdfCoRespJson = JSON.parse(pdfCoRespContent);

  return pdfCoRespJson;
}

/**
 * Uploads File to PDF.co PreSigned URL
 */
function uploadFileToPresignedURL(presignedUrl, fileContent, pdfCoAPIKey){
  // Prepare Request Options
  var options = {
    'method' : 'PUT',
    'contentType': 'application/octet-stream',
    'headers': {
      "x-api-key": pdfCoAPIKey
    },
    // Convert the JavaScript object to a JSON string.
    'payload' : fileContent
  };
  
  // Get Response
  // https://developers.google.com/apps-script/reference/url-fetch
  var pdfCoResponse = UrlFetchApp.fetch(presignedUrl, options);

  if(pdfCoResponse.getResponseCode() === 200){
    return true;
  }
  else{
    return false;
  }
}

/**
 * Save file URL to specific location
 */
function uploadFile(fileUrl) {
  var fileContent = UrlFetchApp.fetch(fileUrl).getBlob();
  folder.createFile(fileContent);
}

PDF.co API requires API Key specified in header for request authentication. You can get it by signing up at https://app.pdf.co/signup.

Thanks, Hiren Patel