CODEWITHSUNDEEP
google-drive-api
chen machluf
chen machluf

Reputation: 61

Google Drive API , Changes api - shared files missing parents field

I try to sync changes from GDrive, So I'm using the changes api. It works like a charm when I'm using it with restrictToMyDrive=true.

But when I tried to expand it to also track shared files restrictToMyDrive=false I encounter some major drawback. I have inconsist results - the parents field is missing sporadically.

Let say that we have user A that share that folder to user B:

rootSharedFolder => subFolder => subSubFolder => File

If user B calls the changes API relatively close to the time that user A share the rootSharedFolder , Then in 3/10 times some of the inner folder will be received without the parents field.

Even trying to use the files.get API on the received changed item , results in empty parents field. But if I wait a minute or two and then call it again , the parents field does exist in the result.

Anyone else encounter this problem , and maybe have a workaround for it?

Thanks!

this behavior happens only when calling the changes api close to the time that the other user share you the items

Upvotes: 4

Views: 869

Answers (1)

yuri
yuri

Reputation: 3400

Parents field may be missing due two factors:

  1. A propagation delay
  2. Insufficient permissions to see the parents

In both cases you'll notice the same: the parents field for the file is missing, at first there is no way to tell in which case you are:

A propagation issue:

This may happen when you request some file details related to a shared file not owned by you right after it was shared to you.

You may not be able to find it's related parents at first glance, this is because changes are still propagating on the file system, this is call a propagation issue, it should not last long and it should be possible to identify and solve this inconvenience by retrieving this field data a couple of minutes after the permission changes.

Not having access to the parents:

In this case you may have access to a certain file, but not to it's parent folder, thus, you can not get to know what parent it has, because it's not been shared with you.

This is on the documentation:

  • parents — A parent does not appear in the parents list if the requesting user is a not a member of the shared drive and does not have access to the parent. In addition, with the exception of the top level folder, the parents list must contain exactly one item if the file is located within a shared drive.

Side note: you may be interested on using SharedDrives, where files are owned by a organization rather than individual users, simplifying the sharing process and maybe avoiding the problems you are facing here.

https://developers.google.com/drive/api/v3/enable-shareddrives

How to know which case is?

A way to go is to implement an exponential back-off algorithm to try to retrieve the missing parents field, if after a max number of attempts it does not retrieve we are probably on the second case:

exponentialBackoff(getParent, 7, 300, function(result) {
    console.log('the result is',result);
});

// A function that keeps trying, "getParent" until it returns true or has
// tried "max" number of times. First retry has a delay of "delay".
// "callback" is called upon success.

function exponentialBackoff(toTry, max, delay, callback) {
    console.log('max',max,'next delay',delay);
    var result = toTry();
    
    if (result) {
        callback(result);
    } else {
        if (max > 0) {
            setTimeout(function() {
                exponentialBackoff(toTry, --max, delay * 2, callback);
            }, delay);

        } else {
             console.log('we give up');   
        }
    }
}

function getParent() {
    var percentFail = 0.8;
    
    return Math.random() >= 0.8;
}

Upvotes: 4

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