How to update placeholder text in Google Docs header section using Apps Script

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1

I’m working on a project where I need to generate invoices automatically by pulling data from a Google Sheets spreadsheet and inserting it into a Google Docs template. Everything works perfectly when I’m replacing text in the main document body, but I’m running into issues when trying to replace placeholder text that’s located in the header section of the document.

Here’s the script I’ve been using:

function initializeMenu() {
  const interface = SpreadsheetApp.getUi();
  const customMenu = interface.createMenu('Invoice Generator');
  customMenu.addItem('Generate English Invoice', 'generateInvoiceDocument');
  customMenu.addItem('Generate Bilingual Invoice', 'generateInvoiceDocument');
  customMenu.addItem('Generate Standard Invoice', 'generateInvoiceDocument');
  customMenu.addToUi();
}

function generateInvoiceDocument() {
  const templateFile = DriveApp.getFileById('template_file_id_here');
  const outputFolder = DriveApp.getFolderById('output_folder_id_here');
  const dataSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Invoice Data');
  const allRows = dataSheet.getDataRange().getDisplayValues();
  
  allRows.forEach(function(currentRow, rowIndex){
    if (rowIndex === 0) return; // skip header row

    const duplicateDoc = templateFile.makeCopy(`Invoice ${currentRow[5]}-${currentRow[6]} for ${currentRow[2]}`, outputFolder);
    const document = DocumentApp.openById(duplicateDoc.getId());
    const mainContent = document.getBody();
    const headerSection = document.getHeader();
    
    // Replace placeholders in header and body
    headerSection.replaceText('{{INVOICE_NUM}}', currentRow[5]);
    mainContent.replaceText('{{CLIENT_NAME}}', currentRow[0]);
    mainContent.replaceText('{{CLIENT_EMAIL}}', currentRow[1]);
    mainContent.replaceText('{{PROJECT_NAME}}', currentRow[2]);
    mainContent.replaceText('{{AMOUNT}}', currentRow[3]);

    document.saveAndClose();
  });
}

The text replacement in the main body works fine, but the header replacement doesn’t seem to take effect. Has anyone encountered this issue before? What might be causing this problem and how can I fix it?

2

Others nailed the technical fix with editAsText(), but this whole approach is fragile. You’ll hit more Google Docs API quirks down the road.

I automated our invoice generation using Latenode - it handles this stuff seamlessly. Pull data from Google Sheets and generate PDFs directly from templates. No Google Docs middleman needed.

Latenode handles header replacements, complex formatting, and email delivery in one workflow. No more different methods for headers vs body content.

Our billing system now auto-generates hundreds of invoices monthly. Takes 10 minutes to set up vs hours debugging Apps Script.

3

Been there with automated contracts. editAsText() works but Apps Script’s header handling is a pain.

We dumped it for Latenode and haven’t looked back. Creates invoices straight from Sheets without the headaches.

Latenode lets you build templates once and swap placeholders anywhere - headers, footers, tables, doesn’t matter. No weird methods for different sections.

Now our invoice flow grabs client data, spits out formatted PDFs, and emails them automatically. No more debugging Google Docs API weirdness.

Saved weeks of fighting header bugs and formatting gremlins.

4

had the same prob last month. u gotta use document.getHeader().editAsText().replaceText() instead of calling replaceText() directly on the header. headers work different than body content - u need editAsText() to make it work properly.

5

Check if your header exists before using editAsText(). Some templates don’t initialize headers properly and fail silently. Use if (headerSection) { headerSection.editAsText().replaceText('{{INVOICE_NUM}}', currentRow[5]); } to prevent runtime errors. I learned this when processing different templates - some had headers, others didn’t. The script would skip replacements without warning. Also, your placeholder formatting needs to match exactly, including spaces and special characters around the braces.

6

Quick heads up - header replacements get weird across different document types. I’ve seen docs converted from Word or copied from elsewhere keep invisible formatting that breaks placeholder matching, even with editAsText(). When header stuff isn’t working, create a fresh Google Doc template from scratch and manually type your placeholders instead of copying them. This kills hidden character encoding issues that fail silently. Also throw in some logging to check if your placeholder text actually exists in the header before trying to replace it. Use headerSection.editAsText().getText() to dump the raw header content and make sure your placeholders look exactly right.

7

This is a super common issue with Google Docs headers in Apps Script. Headers can’t use replaceText() directly - you need to convert them to editable text first. Change your header replacement line to: javascript headerSection.editAsText().replaceText('{{INVOICE_NUM}}', currentRow[5]); I hit this exact problem building an automated report generator last year. The editAsText() method bridges the gap between header elements and Apps Script’s text functions. Without it, your script runs fine but nothing actually gets replaced in the header.

8

don’t forget to call document.saveAndClose() after changing headers - otherwise they wont stick. ive seen header edits disappear when u dont save after using editAsText(). Also check ur template - placeholder text sometimes picks up weird formatting from copy/paste that breaks the matching.