How to upload an existing file in Drive to Drive using Apps Script

Question

Introduction

Let me first introduce the goal of what I am trying to do.

• I had a file split into two parts earlier

• Si

Answer 1

From your question and replying, I could understand your situation and goal like below.

• In your sample files, "file A" and "file B" are 524,288 bytes and 163,339 bytes, respectively.
• Your tested script is the script showing in your question.
• You want to merge the files using the resumable upload.
• The mimeType of the merged file is PDF.

For this, how about this answer?

Modification points:

• Unfortunately, your script is incomplete for achieving the resumable upload. The flow of the resumable upload at Google Drive API is as follows. Ref

  1. Request for retrieving the location which is used as the endpoint for uploading data.
     • In your case, the new file is created. So it is required to use the POST method.
  2. Request to the retrieved location by including the data (in your case, it's each file.).
     • In this case, it is required to upload the data using a loop. And the PUT method is used.
     • Here, each file size is most important. If the file size except for the last file is not the multiples of 262,144 bytes, the resumable upload cannot be run by an error. Please be careful this.

For above flow, when the sample script is prepared, it becomes as follows.

Usage:

1. Enable Drive API.

In this case, Drive API is used. So please enable Drive API at Advanced Google Services. By this, the Drive API is automatically enabled at API console.

The flow of the sample script is as follows.

1. Create an object for using at the resumable upload.
2. Retrieve "location" for starting the resumable upload.
3. Upload each file and merge them.

2. Sample script.

Please copy and paste the following script. And please set the file IDs. In this case, please set them in order for merging. Please be careful this.

function myFunction() {
  const fileIds = ["###", "###"];  // Please set the file IDs of the file "A" and "B" in order.
  const filename = "sample.pdf";
  const mimeType = MimeType.PDF;

  // 1. Create an object for using at the resumable upload.
  const unitSize = 262144;
  const fileObj = fileIds.reduce((o, id, i, a) => {
    const file = DriveApp.getFileById(id);
    const size = file.getSize();
    if (i != a.length - 1 && (size % unitSize != 0 || size > 52428800)) {
      throw new Error("Size of each file is required to be the multiples of 262,144 bytes and less than 52,428,800 bytes.");
    }
    o.files.push({data: file.getBlob().getBytes(), range: `bytes ${o.size}-${o.size + size - 1}\/`, size: size.toString()});
    o.size += size;
    return o;
  }, {size: 0, files: []});

  // 2. Retrieve "location" for starting the resumable upload.
  const url = "https://www.googleapis.com/upload/drive/v3/files?uploadType=resumable";
  const res1 = UrlFetchApp.fetch(url, {
    method: "post",
    contentType: "application/json",
    payload: JSON.stringify({name: filename, mimeType: mimeType}),
    headers: {authorization: "Bearer " + ScriptApp.getOAuthToken()
  }});
  const location = res1.getHeaders().Location;

  // 3. Upload each file and merge them.
  fileObj.files.forEach((e, i) => {
    const params = {
      method: "put",
      headers: {"Content-Range": e.range + fileObj.size},
      payload: e.data,
      muteHttpExceptions: true,
    };
    const res = UrlFetchApp.fetch(location, params);
    const status = res.getResponseCode();
    if (status != 308 && status != 200) {
      throw new Error(res.getContentText());
    }
    if (status == 200) {
      console.log(res.getContentText())
    }
  });

  // DriveApp.createFile()  // This comment line is used for automatically detecting the scope of "https://www.googleapis.com/auth/drive" by the script editor. So please don't remove this line.
}

Result:

When the resumable upload is finished, the following result can be seen at the log. And you can see the merged file at the root folder.

{
 "kind": "drive#file",
 "id": "###",
 "name": "sample.pdf",
 "mimeType": "application/pdf"
}

Note:

• This is a simple sample script. So please modify this for your actual situation.
• I tested above script for your sample situation that "file A" and "file B" are 524,288 bytes and 163,339 bytes. So when several files with about 50 MB in size are merged using this script, an error occurs.
• If the memory error occurs when the large files are used, in the current stage, it seems that this is the specification of Google side. So please be careful this.

Reference:

• Perform a resumable upload