any way to get file size from url without downloading it using google app script.?

Question

Actually I don't know how can I make a head request and read content-length. I tried to write this function:

function getfilesize(url) {
  var msg = '';
  var response;

  try {
    response = UrlFetchApp.fetch(url, {
      // muteHttpExceptions: true,
      // validateHttpsCertificates: false,
      followRedirects: true  // Default is true anyway.
    });
catch(e) {
    return e.toString();
  }

var headers = response.getHeaders();
      var content_length = NaN;
      for (var key in headers) {
        if (key.toLowerCase() == 'Content-Length'.toLowerCase()) {
          content_length = parseInt(headers[key], 10);
          break;
        }

      }
return content length;
}

but it returns a value of 1.81619173E8 for 173mb in 60 sec. Can anyone suggest another way of doing it faster with google apps script?

Answer 1

Your code is probably about correct. That 1.81619173E8 is 1816191730 bytes, which is 173MB. Content-Length is always in bytes.

To convert it to MB, just divide by 1024 twice (once puts it in KB, once more for MB).

content_length = parseInt(headers[key], 10) / 1024 / 1024;

For changing the request type, it looks like fetch() won't accept HEAD directly, but you can use the X-HTTP-Method header to override it:

response = UrlFetchApp.fetch(url, {
  method: 'GET',
  headers: {'X-HTTP-Method-Override': 'HEAD'},
  followRedirects: true  // Default is true anyway.
});

That should get it to use HEAD instead of GET.

Answer 2

I think its taking a long time because you are actually downloading the content.

I found that for my circumstance, I was able to use the Range header to request 0 bytes and then inspect the response headers which held the file size:

var params = {
    method: "GET",
    headers: {
      Range: "bytes=0-0",
    },
  };
  var response = UrlFetchApp.fetch(fileUrl,params);
  var headers = response.getHeaders();
  var fileSizeString = headers['Content-Range']
  var fileSize = +headers['Content-Range'].split("/")[1];

The response headers had Content-Range=bytes 0-0/139046553 as a value that I could then use to convert to an integer (139046553) number of bytes.