#26634: Add the ability to do subselects for querying versioned data
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Reporter: dhobbs | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 1.8
Severity: Normal | Keywords: QuerySet.extra
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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I have versioned data of the form:
id (autogenerate)
ref (uuid)
version (integer)
Each 'save' inserts a new version with the same ref and (version+1)
version number.
I'd like an easy way to say 'give me the latest versions' (ie. distinct on
refs, with max(version)).
The SQL looks like this:
select * from myapp_project where
id in (SELECT id from myapp_project p WHERE p.version = (SELECT
max(version) FROM myapp_project p1 WHERE p1.ref = p.ref))
I had to use extra(where=[maxids]) to achieve this*.
*Where maxids = "id in (SELECT id from myapp_project p WHERE p.version =
(SELECT max(version) FROM myapp_project p1 WHERE p1.ref = p.ref))"
Stackoverflow discussion here:
http://stackoverflow.com/questions/37303010/what-is-the-django-way-of-
doing-a-subselect
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Ticket URL: <https://code.djangoproject.com/ticket/26634>
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