#36441: Add lazy loading support for GDAL library in `django.contrib.gis.gdal`
-------------------------------------+-------------------------------------
Reporter: Josh Thomas | Type:
| Cleanup/optimization
Status: new | Component: GIS
Version: dev | Severity: Normal
Keywords: gdal | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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I'd like to propose enabling lazy loading of the GDAL library in
`django.contrib.gis.gdal`, matching the existing behavior of
`django.contrib.gis.geos` with the GEOS library.
Currently, calling `django.setup()` on projects using GeoDjango fails if
GDAL is not installed, even when GDAL functionality is not being used.
This creates an inconsistency in the GeoDjango framework where the GEOS
library supports lazy loading (implemented ~10 years ago) but GDAL does
not. The proposed change would implement lazy loading for the GDAL module
similar to the existing GEOS implementation, ensuring the GDAL library is
only loaded when actually accessed or used.
I have a working proof-of-concept in a
[https://github.com/joshuadavidthomas/django/tree/lazy-gdal branch] on my
fork of the Django repo ready for review
([https://github.com/django/django/compare/main...joshuadavidthomas:django
:lazy-gdal diff]).
The implementation follows the same approach as the original GEOS lazy
loading commit, wrapping the library loading in `SimpleLazyObject` and
converting function prototypes to use lazy loading. The public API remains
unchanged (everything imported in `django/contrib/gis/gdal/__init__.py`
continues to work as before), though the imports related to the GDAL
version from `django.contrib.gis.gdal.libgdal` now use lazy evaluation.
The existing test suite passes without modification, and I've added new
tests specifically for the lazy loading behavior. Documentation updates
have not been included yet as I wasn't sure if that was needed for a
change like this.
I have created both a [https://forum.djangoproject.com/t/proposal-lazy-
loading-for-django-contrib-gis-gdal/41198 forum post] and an
[https://github.com/django/new-features/issues/42 issue on django/new-
features]. Both have only been open for a few days, so not a ton of time
for people to see them. However, the initial reception has been positive,
with the forum post receiving several likes and the new-features issue
getting only thumbs-up reactions.
--
Ticket URL: <https://code.djangoproject.com/ticket/36441>
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