Etag and LastModifiedDate donot change after file editing

Question

After editing a document in GoogleDrive, it seems that the LastModified value doesn't change immediately sometimes. It looks like the value will be updated in a few minutes. I tried to fetch the Etag of the document by DriveSDK, it also happens to the Etag value. This strange behavior stops me getting the document status (modified or not) at real time. Any suggestions will be highly appreciated. [Sample Request and Response] The request is just GoogleDrive ListFiles : https://www.googleapis.com/drive/v2/files Here's the part of the response JSON, and you can see that the ModifiedDate is earlier than ModifiedByMeDate. ``` { "kind": "drive#fileList", "etag": "\"3NNCnvnQuji-pODa6SMQ6atlc3M/oKnf21kAcJKTCIycS597xCSR2bk\"", "selfLink": "https://www.googleapis.com/drive/v2/files", "items": [ { "kind": "drive#file", "id": "1lZjcJIf3Chuu5upFqtiqfTRnRw7*****rFL_tlO8A", "etag": "\"3NNCnvnQuji-pODa6SMQ6atlc3M/MTM1NDY5MzMyMzQ1Mg\"", "selfLink": "https://www.googleapis.com/drive/v2/files/1lZjcJIf3C…

Accepted Answer

This doesn't answer the question but I would just like to comment on what `etag` and `modifiedDate` means on `File` resources. `File` `etag` seems to just directly correspond to the `modifiedDate` value. The second part of the `etag` (after the slash) is just an encoding of the `modifiedDate`.

In the Documents List API, there's a property called `app:edited` besides the `updated` property (which seems to correspond to `modifiedDate` here). The way these timestamps change are not clearly documented, but I've noticed that `app:edited` changes on virtually every change (e.g. starring of a file, even by another user if I remember correctly) and `updated` changes are more limited (e.g. for content modifications and permission changes). And the `etag` before directly corresponds to `app:edited`, which is good because a change of `app:edited` indicates that there was really a change (sometimes it changes too much though, like starring of a file by a different user, as it doesn't really affect the current user's metadata).

What I want to say is that I think Documents List's `etag` (and having the `app:edited` property) is better than the Drive API having `modifiedDate` only. The problem with the latter is that you don't have a reliable way to determine if a `File` resource has changed or not. For example, if you just like to check if a `File` resource has changed, you could've used the files.get method with an `If-None-Match` header using the `etag`. But `etag` doesn't always change because `modifiedDate` doesn't always change. It changes, for example, when there's new content, or changed ACL, or changed description, but does not change, for example, when trashed, or parents changed. When comparing two resources, you can't reliably determine which one is newer. Add the fact that `modifiedDate` can be set (e.g. it would be possible to set the `modifiedDate` to an earlier value, or even a constant value, and the `etag` with it). The intended purpose of `etag` is lost. There are many cases where we can't just rely on the changes list, and if `etag` behaves properly, it would be huge help for determining the changes that happened.

What I suggest is to restore the behavior of `etag` to be similar to the Documents List API. And to help in determining which resource has newer information, add back the `app:edited` property as well (I think just documenting the value of `etag` is enough, like officially saying that the second part is an encoding of a timestamp, so that we can rely on it to be always increasing). Also, I think it's better to just change the `modifiedDate` property on content modification, and nothing else (e.g. not with ACL changes or description changes).

Similarly, `etag` of `Revision(List)` resources of verbatim files is not very useful as well. Since the `downloadUrl` property changes regularly, the `etag`s of each `Revision` and the whole list changes with it, rendering it useless (because you can't use it to check if the revisions didn't change). Good thing there is the `md5Checksum` property you can compare, but it's not reliable in some cases.

Etag and LastModifiedDate donot change after file editing

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