#25499: Distance lookup not possible with a column value as distance
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Reporter: iambibhas | Owner:
Type: New feature | Status: new
Component: contrib.postgres | Version: master
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Right now this is possible -
{{{
current_localities = Locality.objects.filter(centroid__distance_lte=(pnt,
1000))
}}}
which results in -
{{{
(0.005) SELECT "map_locality"."id", "map_locality"."name",
"map_locality"."slug", "map_locality"."centroid", "map_locality"."radius"
FROM "map_locality" WHERE ST_Distan
ce_Sphere("map_locality"."centroid",
ST_GeomFromEWKB('\x0101000020e6100000865ad3bce3685340e9b7af03e7ec2940'::bytea))
<= 1000 LIMIT 21;
}}}
But if I have a column named `radius` which has the radius for each
Locality and `centroid` has the center point and I want to find all the
localities that my current location falls in, I want to do something like
this -
{{{
current_localities = Locality.objects.filter(centroid__distance_lte=(pnt,
F('radius')))
}}}
But it's not possible right now. It generates the error -
ProgrammingError at /api/services/
can't adapt type 'F'
But in reality, this is possible -
{{{
SELECT "map_locality"."id", "map_locality"."name", "map_locality"."slug",
"map_locality"."centroid", "map_locality"."radius" FROM "map_locality"
WHERE ST_Distance_Sphere("map_locality"."centroid",
ST_GeomFromEWKB('\x0101000020e6100000865ad3bce3685340e9b7af03e7ec2940'::bytea))
<= radius*1000 LIMIT 21;
}}}
Here I'm using `radius*1000` as the result of `ST_Distance_Sphere()` is in
meter and my radius value is in km. I'm looking for suggestions on how to
handle cases like this in the ORM, but I do think that the support for
using a column value using `F()` would be *really* helpful.
--
Ticket URL: <https://code.djangoproject.com/ticket/25499>
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