Hi there,
I quite often find that when using queryset.values() I would like to be
able to define myself the values of the keys, especially when they span
models:
e.g.
my_query_set.values('foo__bar__baz', 'quux',
'another__long__field__name')
Then I end up with dictionaries with unnecessarily long keys. What I'd
like to be able to do is something like:
my_query_set.values('quux', baz='foo__bar__baz',
name='another__long__field__name')
Executing this would yield dictionaries of the type:
{'quux': 2, 'baz': 'type 2', 'name': 'Frobulon'}
I've had a quick look at the ValuesQuerySet class and there seems to be a
simple enough way to get this feature. I'm presenting it in the form of a
new ValuesQuerySet subclass and a monkey patch to the parent QuerySet.
It's not unlikely that it will break some things as this is my first peek
into the QuerySet class. I'd like to know if this is something that other
people feel the need for and if it is worth pushing for inclusion of such a
feature into django.
Cheers,
Arnaud
----------------
from django.db.models.query import QuerySet, ValuesQuerySet
class ValuesDictQuerySet(ValuesQuerySet):
def iterator(self):
# Purge any extra columns that haven't been explicitly asked for
extra_names = list(self.query.extra_select)
field_map = self.field_map
field_names = [field_map.get(fname, fname) for fname in
self.field_names]
aggregate_names = list(self.query.aggregate_select)
names = extra_names + field_names + aggregate_names
for row in self.query.get_compiler(self.db).results_iter():
yield dict(zip(names, row))
def _clone(self, klass=None, setup=False, **kwargs):
c = super(ValuesDictQuerySet, self)._clone(klass, **kwargs)
c.field_map = self.field_map
return c
def QuerySet_values_dict(self, *field_list, **field_dict):
fields = list(field_list)
fields.extend(field_dict.values())
field_map = dict(zip(field_dict.values(), field_dict.keys()))
return self._clone(klass=ValuesDictQuerySet, setup=True,
_fields=fields, field_map=field_map)
# Now we monkey-patch QuerySet with the new method
QuerySet.values_dict = QuerySet_values_dict
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