[Django] #24592: order_by HStore Key/Value Pair
Django
------------------------------+--------------------------------------------
Reporter: DavidMuller | Owner:
Type: | Status: new
Uncategorized |
Component: | Version: 1.8
contrib.postgres |
Severity: Normal | Keywords: hstore postgres order_by value
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
------------------------------+--------------------------------------------
I am currently trying out Django 1.8's HStore implementation, but am
having trouble using the ORM's order_by function.
Say I have HStore dictionaries stored in my database like
{{{
{'key': 'value', 'en-US': 'english'}
}}}
and would like to order a queryset by the strings pointed to by one
particular key.
I run into 2 distinct errors trying to 'order_by' either key ('key' or
'en-US'):
1.
{{{
MyModel.objects.order_by('name__key')
/usr/local/etc/virtualenvs/gears/local/lib/python2.7/site-
packages/django/db/models/sql/query.py in names_to_path(self, names, opts,
allow_many, fail_on_missing)
1427 raise FieldError(
1428 "Cannot resolve keyword %r into field.
Join on '%s'"
-> 1429 " not permitted." % (names[pos + 1],
name))
1430 break
1431 return path, final_field, targets, names[pos + 1:]
FieldError: Cannot resolve keyword 'key' into field. Join on 'name' not
permitted.
}}}
2.
{{{
MyModel.objects.order_by('name__en-US')
/usr/local/etc/virtualenvs/gears/local/lib/python2.7/site-
packages/django/db/models/sql/query.py in add_ordering(self, *ordering)
1717 errors.append(item)
1718 if errors:
-> 1719 raise FieldError('Invalid order_by arguments: %s' %
errors)
1720 if ordering:
1721 self.order_by.extend(ordering)
FieldError: Invalid order_by arguments: ['name__en-US']
}}}
Is ordering by a particular key/value pair not something the ORM supports
(or plans on supporting)?
--
Ticket URL: <https://code.djangoproject.com/ticket/24592>
Django <https://code.djangoproject.com/>
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Django
Reporter: DavidMuller | Owner:
Type: Uncategorized | Status: new
Component: contrib.postgres | Version: 1.8
Severity: Normal | Resolution:
Keywords: hstore postgres | Triage Stage: Accepted
order_by value |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
Changes (by jarshwah):
* needs_better_patch: => 0
* stage: Unreviewed => Accepted
* needs_tests: => 0
* needs_docs: => 0
Comment:
This is definitely something we'd like to support, but I'm not sure if
we're there just yet. To elaborate, I don't think we have support for
Transforms in either `order_by` or `values`. To a user that might not mean
much (since we're conceptually just spanning relationships using the
double underscore `__` notation), but I'm not sure the implementation was
very aware of transforms when we updated order_by.
There are possibly two ways to fix this situation.
1. Make all Transforms into Expressions. That is, we need to consolidate
the very close APIs of Transforms/Lookups and Expressions. We have and we
are discussing this elsewhere (though I can't find where just at the
moment). This is the most likely solution we'll converge on.
2. Make .values and .order_by understand the transformation/lookup API.
We'll probably steer clear of this as it helps to widen the gap between
transforms/expressions.
You can work around this in user code by implementing an `Expression` that
emulates the `KeyTransform` transformation. Something like:
{{{
# UNTESTED!
class KeyAccessor(Func):
function = ''
arg_joiner = ' -> '
output_field = TextField()
def __init__(self, lookup, **extra):
key = lookup.split('__')[-1]
field = lookup.rstrip('__' + key)
super(KeyAccessor, self).__init__(F(field), Value(key), **extra)
Model.objects.order_by(KeyAccessor('related__hstore__keyname').desc())
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/24592#comment:1>
Django
Reporter: DavidMuller | Owner:
Type: Uncategorized | Status: new
Component: contrib.postgres | Version: 1.8
Severity: Normal | Resolution:
Keywords: hstore postgres | Triage Stage: Accepted
order_by value |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by DavidMuller):
Thanks for the very helpful reply @jarshaw. Looking forward to seeing
support in a later Django release
--
Ticket URL: <https://code.djangoproject.com/ticket/24592#comment:2>
Django
Reporter: DavidMuller | Owner:
Type: New feature | Status: new
Component: contrib.postgres | Version: master
Severity: Normal | Resolution:
Keywords: hstore postgres | Triage Stage: Accepted
order_by value |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by timgraham):
* version: 1.8 => master
* type: Uncategorized => New feature
--
Ticket URL: <https://code.djangoproject.com/ticket/24592#comment:3>
Django
Reporter: DavidMuller | Owner:
Type: New feature | Status: new
Component: contrib.postgres | Version: master
Severity: Normal | Resolution:
Keywords: hstore postgres | Triage Stage: Accepted
order_by value |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Comment (by mjtamlyn):
This is heavily related to #23709
--
Ticket URL: <https://code.djangoproject.com/ticket/24592#comment:4>
Django
Reporter: DavidMuller | Owner:
Type: New feature | Status: closed
Component: contrib.postgres | Version: master
Severity: Normal | Resolution: duplicate
Keywords: hstore postgres | Triage Stage: Accepted
order_by value |
Has patch: 0 | Needs documentation: 0
Easy pickings: 0 | UI/UX: 0
Changes (by jarshwah):
* status: new => closed
* resolution: => duplicate
Comment:
Closing as a duplicate of https://code.djangoproject.com/ticket/24747
--
Ticket URL: <https://code.djangoproject.com/ticket/24592#comment:5>