Let's say I have the following models:
class Conversation(Model):
...
class Message(Model):
conversation = models.ForeignKey(Conversation)
The following code counts the number of messages for each conversation:
Conversation.objects \
.filter(...) \
.annotate(size=Count("message")) \
.values("size")
and returns a query set of {'size': 0}, {'size': 1}, {'size': 0}, {'size': 0} etc.
But how do I aggregate over the conversation sizes? That is, obtaining a result something like this: (0, 3), (1, 1), where the first element in each pair is the conversation size and the second element is the number of conversations of this size?
