#33304: Window(order_by) should allow usage of descending string syntax to be
used
-------------------------------------+-------------------------------------
Reporter: Simon Charette | Owner: Simon
Type: | Charette
Cleanup/optimization | Status: assigned
Component: Database layer | Version: dev
(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
-------------------------------------+-------------------------------------
Description changed by Simon Charette:
Old description:
> The `QuerySet.order_by` and
> [https://github.com/django/django/blob/a7e7043c8746933dafce652507d3b821801cdc7d/django/contrib/postgres/aggregates/mixins.py#L11-L14
> some aggregates ordering kwarg] allows for the leading dash syntax to be
> used but `Window.order_by` doesn't as it solely wraps the provided
> `order_by` in `ExpressionList(expressions=order_by)`.
>
> This makes for an inconsistent API so I suggest we reuse the logic in
> `OrderableAggMixin.__init__` in `Window.__init__`
>
> As a related note it seems most of the logic of `OrderableAggMixin` could
> be simplified by using `ExpressionList`.
>
> It's a shame that we used `ordering` and not `order_by` as a kwarg for
> `OrderableAggMixin` as it's now inconsistent. Also not sure how much of a
> ''public'' API the `OrderBy` expression is but I wish it was initially
> named `Sort` (or `Ordering`?) so that we could define
>
> {{{#!python
> class OrderBy(ExpressionList):
> template = 'ORDER BY %(expressions)'
>
> def __init__(self, *expressions, *extra):
> expressions = [
> (Sort(F(o[1:]), descending=True) if isinstance(o, str) and
> o[0] == '-' else o)
> for o in expressions
> ]
> super().__init__(*expressions, **extra)
> }}}
>
> And then simply use this abstraction in `Window` and Postgres orderable
> aggregates.
>
> Assigning to myself as I plan to have a look at this in next few days.
New description:
The `QuerySet.order_by` and
[https://github.com/django/django/blob/a7e7043c8746933dafce652507d3b821801cdc7d/django/contrib/postgres/aggregates/mixins.py#L11-L14
some aggregates ordering kwarg] allows for the leading dash syntax to be
used but `Window.order_by` doesn't as it solely wraps the provided
`order_by` in `ExpressionList(expressions=order_by)`.
This makes for an inconsistent API so I suggest we reuse the logic in
`OrderableAggMixin.__init__` in `Window.__init__`
As a related note it seems most of the logic of `OrderableAggMixin` could
be simplified by using `ExpressionList`.
It's a shame that we used `ordering` and not `order_by` as a kwarg for
`OrderableAggMixin` as it's now inconsistent. Also not sure how much of a
''public'' API the `OrderBy` expression is but I wish it was initially
named `Sort` (or `Ordering`?) so that we could define
{{{#!python
class OrderBy(ExpressionList):
template = 'ORDER BY %(expressions)s'
def __init__(self, *expressions, *extra):
expressions = [
(Sort(F(expr[1:]), descending=True) if isinstance(expr, str)
and expr[0] == '-' else expr)
for expr in expressions
]
super().__init__(*expressions, **extra)
}}}
And then simply use this abstraction in `Window` and Postgres orderable
aggregates.
Assigning to myself as I plan to have a look at this in next few days.
--
--
Ticket URL: <https://code.djangoproject.com/ticket/33304#comment:2>
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