The Google Drive API makes it easy to share files and folders with other users programmatically with the help of Apps Script.

For instance, here’s a snippet of code that will let you share the file with another Google Account user and provide them edit access to the file. Replace the role from writer to reader to give them read-only access.

const shareFilesInGoogleDrive = (fileOrFolderId, emailAddress) => {
  Drive.Permissions.insert(
    {
      role: 'writer', // or "reader" or "commenter"
      value: emailAddress,
      type: 'user',
    },
    fileOrFolderId,
    {
      supportsAllDrives: true,
      sendNotificationEmails: true,
    }
  );
};

It is recommended that you set the sendNotifications flag to true as it will send an email notification when the file is shared with a user who may not have a Google account.

Share Files with Multiple Users

A limitation of the Drive API is that you can only share files with one user at a time. Google Apps Script is synchronous - it doesn’t support the async/await pattern of JavaScript Promises and you therefore cannot run the code in parallel.

There’s however a simple workaround to help you share a file or folder in Google Drive with multiple users in one go in parallel using the UrlFetchApp service.

const shareGoogleDriveFileWithMultipleUsers = () => {
  const fileId = '<Drive File Id>';
  const editors = ['angus@gmail.com', 'kiran@school.edu', 'jacob@corp.com'];

  const API = 'https://www.googleapis.com/drive/v3/files';
  const queryString = 'supportsAllDrives=true&sendNotifications=true';
  const accessToken = ScriptApp.getOAuthToken();

  const requests = editors.map((emailAddress) => ({
    url: `${API}/${fileId}/permissions?${queryString}`,
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      Authorization: `Bearer ${accessToken}`,
    },
    muteHttpExceptions: true,
    payload: JSON.stringify({
      role: 'writer',
      type: 'user',
      emailAddress: emailAddress,
    }),
  }));

  UrlFetchApp.fetchAll(requests);
};

In the snippet above, we are directly invoking the Google Drive API (v3) instead of the DriveApp service of App Script. The fetchAll allows you make multiple HTTP requests in a single request and returns an array of responses.

Please ensure that the following scopes are added in your appsscript.json file:

  {
    ...
    "oauthScopes": [
      "https://www.googleapis.com/auth/script.external_request",
      "https://www.googleapis.com/auth/drive",
    ],
   ...
  }