OSMGeoAdmin should require GDAL only if model has fields with SRID that differs from map srid

[Sergey Fedoseev]

ATM OSMGeoAdmin raises exception while initialization if GDAL isn't available, that seems to be too strong check because GDAL is not needed if SRID of model field is the same as needed by map widget.

[Sergey Fedoseev]

PR -- ​https://github.com/django/django/pull/5770

[Claude Paroz]

I'm a bit hesitant here. Do you see many projects who store there data with the projected spherical mercator (3857)? I'm not even sure we should encourage that.

[Sergey Fedoseev]

Honestly speaking I have deal with the only GIS project =)

My position on this: if we are supporting GIS stuff running even without GDAL we should try to minimize dependency from it as hard as we can while this doesn't lead us to reinventing it.

I could even see imaginable use case for storing the data in 3857: to store it along with the data in 4326 to get rid of the overhead on transforming coordinates every time they are should be represented to the users.

[Tim Graham]

It looks to me like the current error would be raised at compile time. Will the new error be raised at compile time or only when accessing the admin page? I think the former is much better. If the ticket is accepted, it might be better to convert it to a system check if possible.

[Tim Graham]

I'll tentatively accept the ticket given it has sat on the unreviewed queue for several weeks and mark it "patch needs improvement" until GIS contributors decide on whether or not to move forward with it.

[Tim Graham <timograham@…>]

In 1f035e62:

Fixed #25865 -- Made OSMGeoAdmin require GDAL only if transformation is needed.