cant store multiple sized thumbnails with get_thumbnail()

[suneelkingrani]

Hi @pylover , a nice piece of work!

I am trying to make different sizes/widths of thumbnails e.g. width=30 or width=40. For that I am following the basic setup given in your repository /examples/flask. But for some reason I am unable to save/update multiple thumbnails.

suppose I have a Person with an avatar field defined and I want to create two different sized thumbnails:

with StoreManager(db.session()):
	thumbnail = person1.avatar.get_thumbnail(width=32, auto_generate=True)
	db.session.commit()

The value of avatar field in DB, after running the code lines above:

{"key": "ae01a10b-e33f-4234-a1ad-aa32c01ca92c", "extension": ".png", "content_type": "image/png", "reproducible": false, "width": 128, "height": 125, "length": 28101, "timestamp": "1564068229.4194794", "thumbnails": [[32, 31, 0.25, {"key": "54813146-c03c-42c0-8ebe-91d505055ab5", "width": 32, "height": 31, "extension": ".png", "content_type": "image/png", "reproducible": false, "length": 2272, "timestamp": "1564071128.3401299"}]]}

and when I re run the same code to get another thumbnail of different width (40) i.e.:

with StoreManager(db.session()):
	thumbnail = person1.avatar.get_thumbnail(width=40, auto_generate=True)
	db.session.commit()

It does not change anything in avatar field in DB, though I guess it is supposed to append a list for another thumbnail in avatar thumbnails.
Also re running the method get_thumbnail(width=40, auto_generate=True), keeps making new image files in thumbnail directory and changes nothing in the DB.

Can you please let me know if I am doing something wrong?