How to get SQL query for query with Subquery?

Question

I have a query

q = Product.objects \
    .annotate(t=Subquery(Purchase.objects.filter(user=user)))

and when I do print(q.query) I get the following exception:

{FieldError} Cannot resolve expression type, unknown output_field

What to do and why they can't resolve the expression type?

Horatiu Jeflea · Accepted Answer · 2020-06-30 12:45:46Z

1

You need to use .values, to select the field you want to annotate from user

q = Product.objects.annotate(t=Subquery(Purchase.objects.filter(user=user).values('pk')))

answered Jun 30, 2020 at 12:45

Horatiu Jeflea

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