Question

I’m working on file sharing on Google Drive in my android app. Here is the scenario… User A shares a file with User B, gives him/her the “writer” role. Later, forgetful User A, again, shares the same file with User B, giving him/her the “reader” role this time. My question is, will this override the first permission? or should the app handle checking of existing file permissions?

Answer 1

You can use drive.permissions.update to update role property of a permission, provided that you have fileId and permissionId. The role property will be overridden. But if you notice, there is a additionalRoles[] property that will allow you to add secondary roles to that permission given to a user. Right now, only commenter is allowed. Maybe in the future, more roles will be added in that property.

You can confirm by yourself using Google API Explorer:

1. First, send drive.files.list request to get fileId of a shared
   file.
2. Send drive.permissions.list request with the fileId to get
   permissionId of a user (it is the id in the reponse).
3. With fileId and permissionId, now you can use
   drive.permissions.update to change the role of that user by send
   the request with role property in the body.