django complicated agregate in three tables - sql

Question

I have a three tables with one main (Transaction) and two dependant(TransactionDialogMessages, TransactionDialogLastAccess).
class Transaction(models.Model):
status = models.CharField(max_length = 3, default = 'NEW')
user1 = models.ForeignKey(User, related_name='user1', blank=True, null=True, on_delete=models.SET_NULL)
user2 = models.ForeignKey(User, related_name='user2', blank=True, null=True, on_delete=models.SET_NULL)
some_info = models.DateTextField()
class TransactionDialogMessages(models.Model):
transaction = models.ForeignKey(Transaction)
user = models.ForeignKey(User, blank=True, null=True, on_delete=models.SET_NULL)
message = models.TextField()
create_datetime = models.DateTimeField(auto_now = True)
class TransactionDialogLastAccess(models.Model):
transaction = models.ForeignKey(Transaction)
user = models.ForeignKey(User, blank=True, null=True, on_delete=models.SET_NULL)
access_time = models.DateTimeField()
I want to create one query with complex agregation on this three tables, and result in hash (or queryset) with such structure:
{'transaction_id', 'status', 'user1', 'user2', 'some_info', 'count_of_new_messages'}
where count_of_new_messages is agregation field, which computed as
count (TransactionDialogMessages(transaction = transaction_id, user = request.user, create_datetime > TransactionDialogLastAccess(transaction = transaction_id, user = request.user).access_time))
Is it real?
Updated:
I created SQL query, which serves my purpose:
SELECT a.id, a.status, ... , b.COUNT_OF_NEW_MESSAGES FROM transaction a
LEFT JOIN (SELECT b.transaction_id, COUNT(b.transaction_id) AS COUNT_OF_NEW_MESSAGES
FROM transactiondialogmessages b
LEFT JOIN transactiondialoglastaccess c
ON b.transaction_id = c.transaction_id
WHERE b.create_datetime > c.access_time OR c.access_time IS NULL
GROUP BY b.transaction_id ) b
ON a.id = b.transaction_id;
But how it's realize on django orm (without raw)?