I need to concatenate text docs 1,2,3 into 4. How?

Question

I have a bunch of Google Docs that I want to concatenate into a fresh new doc. Basically I want to do the equivalent of the Unix command:

cat 1.txt 2.txt 3.txt >4.txt

I can't seem to figure out the best way to do this from the Apps Scripts documentation. Would anyone happen to know?

I tried the following:

// ... code omitted
var entries = [];
while (files.hasNext()) {
    var file = files.next();
    var name = file.getName();
    if (file.getOwner().getName() != 'My Name') continue

    var re = /Pattern I am looking for - \d\d/g;
    if (name.match(re) == null) continue;

    entries.push( {"Name" : name, "File" : file} );
}
entries.sort(function(a,b) { return a.Name.localeCompare(b.Name); });

// Open the Full.txt file and add each file into it in sequence.
var fullDoc = DocumentApp.create('Full.txt');
entries.forEach(function(e) {
    var contents = e.File.getAs('text/plain');
    // Haven't yet gotten to sticking contents into the target file
    // because content retrieval itself fails with the message:
    //  "Converting from application/vnd.google-apps.document to text/plain 
    //  is not supported. (line 51, file "DocMerge")"
    return;
  });

Thanks.

-av

Answer 1

You need to open the Files using DocumentApp, so you can retrieve the document contents. As you are seeing, straight conversion to plaintext is not supported (although it would be convenient).

var source_doc = DocumentApp.openById(e.File.getId());
var contents = source_doc.getBody().getText();

Depending on your use case, you may also want to get the header/footer sections, and you could also skip using getText() and use Body.copy() to create a copy of the body element you can then insert into the other doc. This approach would preserve formatting.