Incorrect modified time for artstation images

[sbstratos79]

Originally opened this issue in hydownloader repo.

Moving the issue here since it seems to be a problem with gallery-dl.

The modified time associated with most artstation images is the download time instead of the published date. The reason I said "most" is because some artstation images do in fact display the correct modified time. A lot of these correctly tagged files are gif but some are jpg as well. So I can't figure out the pattern. Booru images display the correct modified time however.

[AlttiRi]

For example: https://www.artstation.com/artwork/B121mD

It seems that /large/ still has the correct (?) last-modified header (Sun, 19 Sep 2021 21:39:04 GMT), but /4k/ does not (it has the current time value).

It's not a temporal server issue, for example, files are downloaded in May also have such mtimes.
I assume it's since #1422.

I think it makes sense to use the time from API response by default.
However, there are 3 different times:

  "created_at":   "2020-10-27T09:00:23.886-05:00",
  "updated_at":   "2022-11-02T04:51:18.469-05:00",
  "published_at": "2020-10-27T09:00:29.408-05:00",

Possibly, created_at is the more appropriate time.
Usually last-modified is the time of an upload of a file to a server.

date key already uses "created_at"'s value.

[AlttiRi]

The manual fix is just to add a mtime postprocessor in the config file:

        "artstation": {
            "directory": ["[gallery-dl]", "[{category}] {user[username]}—{user_id}—{userinfo[full_name]}"],
            "filename": "[{category}] {user[username]}—{date:%Y.%m.%d}—{hash_id}—{id}—{asset[id]}—{filename}—{title}.{extension}",
            "fallback": false,
            "postprocessors": [{
                "name": "mtime"
            }]
        },

[sbstratos79]

Adding mtime postprocessor did the trick. Thanks! I will keep this issue open for now.