How to add header section in merged Google document via Google Apps script?

Question

I'm trying to merge 2 Google doc files using their ids. Below is the code snippet I followed.

  var docIDs = ['documentID_1', 'documentID_2', 'documentID_3', 'documentID_4'];
  var baseDoc = DocumentApp.openById(docIDs[0]);

  var body = baseDoc.getActiveSection();

  for (var i = 1; i < docIDs.length; ++i) {
    var otherBody = DocumentApp.openById(docIDs[i]).getActiveSection();
    var totalElements = otherBody.getNumChildren();
    for (var j = 0; j < totalElements; ++j) {
      var element = otherBody.getChild(j).copy();
      var type = element.getType();
      if (type == DocumentApp.ElementType.PARAGRAPH) body.appendParagraph(element);
      else if (type == DocumentApp.ElementType.TABLE) body.appendTable(element);
      else if (type == DocumentApp.ElementType.LIST_ITEM) body.appendListItem(element);
      else throw new Error('Unknown element type: ' + type);
    }
  }

The merged document looks fine. But the header and footer section is not added in the merged document. I can see there is a header and footer section in the original document. Someone, please help me to fix this.

Answer 1

The script you're using is only working with certain elements from a document like paragraphs, tables and lists. I made some updates to the script to get the HeaderSection and FooterSection as well.

You can try the following script:

UPDATED SCRIPT

function myFunction() {
  var docIDs = ['documentID_1', 'documentID_2'];
  var newDoc = DocumentApp.create('Document Name');//You can change the name of the new document
  var newDocID = newDoc.getId();
  var baseDoc = DocumentApp.openById(newDocID);
  baseDoc.addHeader();
  baseDoc.addFooter();

  var body = baseDoc.getBody();
  var bodyHeader = baseDoc.getHeader();
  var bodyFooter = baseDoc.getFooter();

  for (var i = 0; i < docIDs.length; ++i) {
    var otherBody = DocumentApp.openById(docIDs[i]).getBody();
    var otherHeader = otherBody.getParent();
    var totalEl = otherHeader.getNumChildren();
    var totalElements = otherBody.getNumChildren();

    for (var j=0; j < totalEl; ++j){
      var el = otherHeader.getChild(j).copy()
      var t = el.getType();
      if (t == DocumentApp.ElementType.BODY_SECTION) continue;
      else if (t == DocumentApp.ElementType.HEADER_SECTION){
        var header = otherHeader.getChild(j).asHeaderSection().getText();
        bodyHeader.appendParagraph(header);
      }
      else if (t == DocumentApp.ElementType.FOOTER_SECTION){
        var footer = otherHeader.getChild(j).asFooterSection().getText();
        bodyFooter.appendParagraph(footer);
      }
      else throw new Error('Unknown element type: ' + type);
    }

    for (var k = 0; k < totalElements; ++k) {
      var element = otherBody.getChild(k).copy();
      var type = element.getType();
      if (type == DocumentApp.ElementType.PARAGRAPH) body.appendParagraph(element);
      else if (type == DocumentApp.ElementType.TABLE) body.appendTable(element);
      else if (type == DocumentApp.ElementType.LIST_ITEM) body.appendListItem(element);
      else throw new Error('Unknown element type: ' + type);
    }
  }
}

I tested the script with Google docs that includes headers/footers and it worked. I'm sure there is a better way to achieve this but at least it can give you an idea on how to work with different elements of a Google Doc.

If you have any questions let me know.