Creating a Django object with field values from a SELECT equivalent - django

Question

I am trying to figure out how to reproduce the following using Django - anyone help?
INSERT INTO table1 (table2_id, a_field)
SELECT table2.id as table2_id, table3.a_field
FROM table2
INNER JOIN table3 ON
table3.table2_id == table2.id
WHERE table2.id = 123
If I've got this correct (not my original query ;-) ), this is doing the following:
Creating an entry in table1 where...
a field named table2_id will match the id of a row in table2 and
a field named a_field will match the same named field in a_field in a row of table3 and
the table2/table3 objects from which these values are read are identified by a shared table2.id/table3.table_id2 relationship and also the table2 id being 123.
I don't see how such "calculated" field values can be passed to a create() or get_or_create() style command. It this perhaps possible using Q() objects?

Answer 1

Django model is an ORM framework.
In ORM way, you need
get table2Entity
construct a new table1Entity with table2Entity and related table3Entity values
save the table1Entity
def batch_save_entity2():
entity2 = Table2Entity.objects.get('123')
entity1 = Table1Entity()
entity1.table2_id = entity2.id
entity1.a_field = entity2.entity3.a_field
entity1.save()
or just execute sql directly without ORM
from django.db import connection
def my_custom_sql(self):
with connection.cursor() as cursor:
cursor.execute('''
INSERT INTO table1 (table2_id, a_field)
SELECT table2.id as table2_id, table3.a_field
FROM table2
INNER JOIN table3 ON
table3.table2_id == table2.id
WHERE table2.id = 123''')