Django ORM call to obtain multiple fk values? - django

Question

models.py (derived from existing db)
class IceCreamComponent(models.Model):
name = models.CharField
#can be 'flavor', 'nut', etc
class IceCream(models.Model):
name = models.CharField
component = models.ForeignKey(IceCreamComponent)
value = models.CharField #will correspond to the component
The context behind this database is that 'IceCream' reports will come in from someone who's only purpose is to report back on a certain component (i.e. my 'extras' reporter will report the name of the ice cream and the extra it contained). It is assumed that all needed reports are in the db when queried so that something like:
IceCreams = IceCream.objects.values('name', 'component__name', 'value')
will return something akin to:
[
{'name': 'Rocky road', 'component__name': 'ice cream flavor', 'value':'chocolate'},
{'name': 'Rocky road', 'component__name': 'nut', 'value':'almond'},
{'name': 'Rocky road', 'component__name': 'extra', 'value':'marshmallow'},
{'name': 'Vanilla Bean', 'component__name': 'ice cream flavor', 'value':'vanilla'},
{'name': 'Vanilla Bean', 'component__name': 'extra', 'value':'ground vanilla bean'},
]
However, as you can imagine something like:
[
{'name': 'Rocky Road', 'ice cream flavor': 'chocolate', 'nut': 'almond', 'extra':'marshmallow' },
{'name': 'Vanilla Bean', 'ice cream flavor': 'vanilla', 'extra':'ground vanilla bean'}
]
is much more usable (especially considering I'd like to use this in a ListView).
Is there a better way to query the data or will I need to loop through the ValuesQuerySet to achieve the desired output?

Answer 1

Can't you reconstruct the list from the original result?
results = []
for row in vqueryset:
converted_row = {}
converted_row[row['component__name']] = row['value']
converted_row['name'] = row['name']
results.append(converted_row)
Of course you would want to paginate the original result before evaluating it (turning it into a list).
oh, you asked if there's a better way. I'm doing it this way because I couldn't find a better way anyway.

Answer 2

Here is the solution I came up with.
processing = None
output = []
base_dict = {}
for item in IceCreams:
# Detect change current site code from ordered list
if item['name'] != processing:
processing = item['name']
# If base_dict is not empty add it to our output (only first one)
# TODO see if there's a better way to do first one
if base_dict:
output.append(base_dict)
base_dict = {}
base_dict['name'] = item['name']
base_dict[item['component__name']] = item['value']