#26112: Aggregate Sum of GIS Aggregates fails
----------------------------+--------------------------------------
Reporter: yellowcap | Owner: yellowcap
Type: Bug | Status: new
Component: GIS | Version: 1.9
Severity: Normal | Resolution:
Keywords: aggregates | Triage Stage: Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
----------------------------+--------------------------------------
Changes (by yellowcap):
* needs_better_patch: => 0
* needs_tests: => 0
* needs_docs: => 0
Old description:
> There is an error when trying to compute a regular aggregate value from
> a GIS aggregate output. To take an example from the GIS geoapp tests, the
> following query fails.
>
> {{{
> from django.db.models import Sum
> from django.contrib.gis.db.models.functions import Area, Intersection
>
> Country.objects.annotate(intersum=Sum(Area(Intersection('mpoly', geom))))
> }}}
>
> I tracked this down to the `from_db_value` function in the GeometryField
> class here:
>
> https://github.com/django/django/blob/master/django/contrib/gis/db/models/fields.py#L259
>
> The problem seems to be that the `Area` function returns a float, but the
> field is expecting a value that can be converted to a Geometry.
>
> I'll open a pull request with a regression test and a proposed solution,
> basically checking if the value is a float or int.
New description:
There is an error when trying to compute a regular aggregate value from a
GIS aggregate output. To take an example from the GIS geoapp tests, the
following query fails.
{{{
from django.db.models import Sum
from django.contrib.gis.db.models.functions import Area, Intersection
Country.objects.annotate(intersum=Sum(Area(Intersection('mpoly', geom))))
}}}
I tracked this down to the `from_db_value` function in the GeometryField
class here:
https://github.com/django/django/blob/master/django/contrib/gis/db/models/fields.py#L259
The problem seems to be that the `Sum` function returns a float, but the
field is expecting a value that can be converted to a Geometry.
I'll open a pull request with a regression test and a proposed solution,
basically checking if the value is a float or int.
--
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Ticket URL: <https://code.djangoproject.com/ticket/26112#comment:1>
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