#36129: Geodjango migrations ignore change of dimension in MultiPointField
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Reporter: Paweł Kotiuk | Owner: (none)
Type: Bug | Status: closed
Component: GIS | Version: dev
Severity: Normal | Resolution: invalid
Keywords: migrations | 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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Changes (by Natalia Bidart):
* cc: Claude Paroz (added)
* keywords: => migrations
* resolution: => invalid
* status: new => closed
* type: Uncategorized => Bug
* version: 5.1 => dev
Comment:
Hello Pawel, thank you for this report. I agree this is similar to the
tickets you linked and also to #23902. Can you specify what backend are
you using?
Based on the previous tickets, and following the comments from Claude, it
seems quite challenging to generate a migration that makes sense for the
backend, in that how the added dimension would work with respect to the
existing values in the DB? For your reproducer specifically, my
understanding is that your last step works because the test DB is created
with a single and "clean" migration where the `dim=3` since the start.
Having said that, I have tried this in a test project and using the admin
to create a point when `dim=2`. Then I changed to `dim=3` and the point
was migrated in the DB as follows (this is PostGIS): `SRID=4326;MULTIPOINT
Z ((-0.0051498413085937 0.0168228146996821 0))`. But I can't add new
points because of the chosen default, which does not have the third
dimension:
{{{
Exception Type: DataError at /admin/geodjangoapp/multipointtester/add/
Exception Value: Column has Z dimension but geometry does not
}}}
So, I ''think'' that this specific report is about the default being
incorrect for a 3-dimension multipoint (which would consitute an user
error), and not so much about migration generation failure, but I'm not a
GIS expert. I was going to propose for you to reach our in the forum, but
I see you have already [https://forum.djangoproject.com/t/bug-geodjango-
migrations-ignore-change-of-dimension-in-multipointfield/38169/2 done so].
Because of my local testing, I'll be closing this ticket as invalid
following the
[https://docs.djangoproject.com/en/dev/internals/contributing/triaging-
tickets/#closing-tickets ticket triaging process], but feel free to reopen
if you find more specific information detailing that Django is at fault in
this specific case, specifically once you remove the potentially incorrect
default in place.
Thanks again!
--
Ticket URL: <https://code.djangoproject.com/ticket/36129#comment:2>
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