#15648: [Feature request] NamedTupleQuerySet
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Reporter: pbagwl | Owner: nobody
Status: new | Milestone: 1.4
Component: Database layer (models, ORM) | Version: SVN
Keywords: namedtuple, tuple, queryset | Triage Stage: Unreviewed
Has patch: 1 |
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Python 2.6 supports named tuples. Information about field names is stored
in the tuple class, so there's no overhead like in dictionaries.
I propose to use them in querysets instead of values() / values_list().
{{{#!python
qs = Items.objects.filter(...).namedtuples('title', 'amount', 'price')
for item in qs:
print item.title, item.amount
total += item.amount * item.price
}}}
Patch:
{{{#!python
from itertools import imap
from collections import namedtuple
# python 2.5 doesn't support named tuples, so we can use this
http://code.activestate.com/recipes/500261/
from django.db.models.query import ValuesQuerySet
class NamedTuplesQuerySet(ValuesQuerySet):
def iterator(self):
# get field names
extra_names = self.query.extra_select.keys()
field_names = self.field_names
aggregate_names = self.query.aggregate_select.keys()
names = extra_names + field_names + aggregate_names
# create named tuple class
tuple_cls = namedtuple('%sTuple' % self.model.__name__, names)
results_iter = self.query.get_compiler(self.db).results_iter()
# wrap every string with our named tuple
return imap(tuple_cls._make, results_iter)
}}}
{{{#!python
from django.db.models.query import QuerySet
def namedtuples(self, *fields):
return self._clone(klass=NamedTuplesQuerySet, setup=True,
_fields=fields)
QuerySet.namedtuples = namedtuples
}}}
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Ticket URL: <http://code.djangoproject.com/ticket/15648>
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