Are distance lookups available for MySQL or not?

[Clara Daia]

Hello, everybody

I am using Django 2.1 with MariaDB 10.3.

I have been trying to get the 'dwithin' lookup to work on a PointField, but I keep getting the following error:

  ...
  File "/usr/local/lib/python3.6/site-packages/django/contrib/gis/db/models/lookups.py", line 74, in get_rhs_op
    return connection.ops.gis_operators[self.lookup_name]
KeyError: 'dwithin'

(To be more precise, I am using this filter backend from a library, which generates the lookup for me.)

Looking at the docs, I get conflicting info:

* this section says "Availability: PostGIS, Oracle, SpatiaLite, PGRaster (Native)", implying 'not available on MySQL'

* this other section says MySQL support was added on Django 2.0

I could switch to PostgreSQL as a last resort, but maybe I'm just forgetting some configuration? Are the distance lookups available for MySQL or not?

Best regards,

Clara

[Clara Daia]

I wrote the query myself in case the library was messing it up and got the same error:

self.assertEqual(MyModel.objects.filter(
    geopositionfield__dwithin=(
        Point(-25.427855, -49.279644),
        0.00028321143293561684)
).count(), 1)

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[Jason]

https://mariadb.com/kb/en/library/mysqlmariadb-spatial-support-matrix/ seems to be a good resource for mariadb gis functions, and as you can see, there's no listing for dwithin.  so while there might be support for mysql, it probably doesn't extend to mariadb

[Clara Daia]

Hello, Jason

I appreciate your help, and I tried running the test with a MySQL container but got the same error.

The MySQL spatial reference does not have a'dwithin' entry or similar either.

I changed my query to

self.assertEqual(MyModel.objects.filter(
    geopositionfield__distance_lt=(

        Point(-25.427855, -49.279644),
        0.00028321143293561684)
).count(), 1)

And it seems to have worked, both on the MySQL and the MariaDB containers.

I suppose there is limited support and the documentation should specify which distance functions are available for MySQL. Do you think I should file a ticket?

Best regards,

Clara

[Clara Daia]

Shame on me, there is a table for that in the docs.

https://docs.djangoproject.com/en/2.1/ref/contrib/gis/db-api/#spatial-lookup-compatibility

[Jason]

nice job in finding the cause and +1 for posting the compatibility table link here for future search reference.