group by in django aggregate function? - sql

Question

I have problem writing group by sql into django app. Can any of you django users help me how to write this sql into django-friendly code? This is my model:
class Stock(models.Model):
name = models.CharField("Stock's name", max_length=200)
symbol = models.CharField("Stock's symbol", max_length=20)
class Dividend(models.Model):
amount = models.FloatField(default=0)
date = models.DateField('pay date')
stock = models.ForeignKey(Stock)
class UserStock(models.Model):
amount = models.FloatField('amount', default=0)
date = models.DateField('buy date')
price = models.FloatField('price', default=0)
user = models.ForeignKey(User)
stock = models.ForeignKey(Stock)
And this is sql code I want to write in django:
select stock_id, sum(price), sum(amount) as price from stocks_userstock group by stock_id;
I was trying to write something like this.
my_stock = UserStock.objects.filter(user=request.user)\
.annotate(sum_price = sum('price'), sum_amount = sum('amount'))
Thanks in advance, I hope it won't be a problem for some of you.

Answer 1

I believe just adding a values call will do that
my_stock = UserStock.objects.get(user=request.user)\
.values('stock_id').annotate(sum_price = sum('price'), sum_amount = sum('amount'))
and you will get back a list of dicts similar to
[
{'stock_id': 0, 'sum_price': 10, 'sum_amount': 25},
...
]
see here for more info

Answer 2

stock = Stock.objects.all().annotate(sum_price = Sum('user_stock__price'), sum_amount = Sum('user_stock__amount'))
It should work.
I've removed the User filter in my snippet to simplify but you can add it of course.