#26192: Cannot order query by constant value
-------------------------------------+-------------------------------------
Reporter: srkunze | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.8
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | 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 srkunze):
* status: closed => new
* resolution: invalid =>
Comment:
> I don't see what the use of ordering by a constant string value is.
Reducing code complexity (e.g. fewer ifs).
The code overview from #26192:
{{{
# 1 create complex queryset
... more code
# 2 annotate and add extra where
... more code
# 3 add order (maybe referring to the extra column)
... more code
# 4 wrap paginator around queryset
... more code
# 5 create values_list of paged queryset
... more code
# 6 evaluate <<<< crash
}}}
The code above spread over several files and few thousand lines builds up
a quite complex query.
Each point contribute to the final queryset (actually more than one
queryset). In order to reduce coupling and code complexity, adding a
constant column make things straightforward (otherwise we would need to
check if the column was added).
> it looks like this is a database limitation.
Are you sure? From what I know of SQL, it's possible to order by column
name (a string) or by column index (a number). Django just creates invalid
SQL.
Why does Django not refer the column order_by by name (or index) and
instead inserts a value?
--
Ticket URL: <https://code.djangoproject.com/ticket/26192#comment:4>
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