#28341: GeometryField doesn't create GEOSGeometry objects lazily anymore
-------------------------------------+-------------------------------------
Reporter: Sergey Fedoseev | Owner: Abhimanyu
| Singh Negi
Type: Bug | Status: assigned
Component: GIS | Version: 1.8
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Abhimanyu Singh Negi):
* owner: (none) => Abhimanyu Singh Negi
Comment:
Hi, I spent some time digging into this and I think I understand what’s
going on.
Right now geometry objects are being created too early. The conversion
happens in the database converter layer —
BaseSpatialOperations.get_db_converters() adds a geometry converter, and
that converter runs in SQLCompiler.apply_converters(). So GEOSGeometry
gets created while rows are being fetched, before the values ever reach
the model instance. Because of that, SpatialProxy never sees raw values
and the lazy-loading path isn’t used.
I traced this through the ORM flow and confirmed that model instances
already contain GEOSGeometry objects in instance.__dict__, which explains
why accessing the field later doesn’t trigger any conversion.
One important detail is that values() and values_list() depend on
converters returning geometry objects immediately, so converters can’t
just be removed. The fix needs to keep eager conversion for those cases
but allow raw values when loading model instances so SpatialProxy can do
the conversion lazily.
I’m going to try implementing this by adjusting the geometry converter /
registration logic so conversion is skipped when loading model instances,
then add a regression test and run the GIS test suite to make sure nothing
else breaks.
Assigning this issue to myself for implementation.
--
Ticket URL: <https://code.djangoproject.com/ticket/28341#comment:9>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion visit
https://groups.google.com/d/msgid/django-updates/0107019c5138e265-0ad11cc1-200a-4677-a4c2-7ac75a6dd481-000000%40eu-central-1.amazonses.com.
