Get original `stac_version` of a STAC object

[soxofaan]

When loading e.g. STAC collection data with Collection.from_dict(), the original stac_version is discarded:

pystac/pystac/collection.py

Line 681 in 7621455

d.pop("stac_version")

Is it intentional that you can not inspect the original stac_version from the STAC document?

[gadomski]

I don't believe it is, I just tested from_file and from_dict:

import requests

import pystac
from pystac import Item

item = pystac.read_file(
    "https://raw.githubusercontent.com/radiantearth/stac-spec/refs/tags/v1.0.0/examples/simple-item.json"
)
print(item.to_dict()["stac_version"])

response = requests.get(
    "https://raw.githubusercontent.com/radiantearth/stac-spec/refs/tags/v1.0.0/examples/simple-item.json"
)
response.raise_for_status()
data = response.json()
item = Item.from_dict(data, migrate=False)
print(item.to_dict()["stac_version"])

Produces:

1.1.0
1.1.0

If you need v1.0.0, I'd stay at pystac v1.11.x for now. STAC version handling is a bit convoluted in pystac so a fix to preserve versions might be non-trivial, though of course PRs welcome!

[soxofaan]

I'm not sure I understand why it would be non-trivial. Wouldn't it be comparable with how "stac_extensions" is managed/preserved?

[keithpeck]

Ability to maintain the original STAC version and not automatically update extensions (projection extension gets automatically upgraded to v2.0.0) would be useful. Use of pystac in our backend is limited as we can't start dropping fields for existing customers.

[gadomski]

I'm not sure I understand why it would be non-trivial. Wouldn't it be comparable with how "stac_extensions" is managed/preserved?

Sorry, dropped this thread, but coming back to it now. You're welcome to give it a shot — I've found it hard to unpick the auto-migration stuff without breaking existing behavior.