Django ORM with Key/Value Table structure - django

Question

I'm trying to get the django orm to replicate a call on a database for my current table structure:
Tables:
ServiceItems {Id, name, user, date_created}
ServiceItemsProps {fk_to_ServiceItems Item_id, Id, key, value}
I'm trying to select items from the ServiceItem table with multiple keys from the ServiceItemsProps table as columns.
I can accomplish this with a query like the following:
> select tbl1.value as bouncebacks, tbl2.value as assignees from
> service_items join service_item_props as tbl1 on tbl1.item_id =
> service_items.id join service_item_props as tbl2 on tbl2.item_id =
> service_items.id where service_items.item_type='CARD' and
> tbl1.key='bouncebacks' and tbl2.key='assignees'
But I'm not able to figure out how to reproduce this in Django's ORM. I would like to not inject raw SQL into the statements here, because codebase portability is important.
Section of models.py
class ServiceItems(models.Model):
class Meta:
db_table = 'service_items'
unique_together = ('service', 'item_type', 'item_id')
service = models.ForeignKey(Service, blank=False, db_column='service_id', on_delete=models.CASCADE)
item_type = models.CharField(max_length=255, blank=False)
url = models.TextField(blank=True, null=True)
item_id = models.TextField(blank=True, null=True)
item_creation_user = models.TextField(blank=True, null=True)
item_creation_date = models.DateTimeField(blank=True, null=True)
created_at = models.DateTimeField(auto_now_add=True)
updated_at = models.DateTimeField(auto_now=True)
class ServiceItemProps(models.Model):
class Meta:
db_table = 'service_item_props'
item = models.ForeignKey(ServiceItems, blank=False, db_column='item_id', on_delete=models.CASCADE)
prop_id = models.TextField(blank=True, null=True)
key = models.CharField(max_length=255, blank=False)
value = models.TextField(blank=True, null=True)

Answer 1

# change one line to make it easier to query
item = models.ForeignKey(ServiceItems, blank=False, db_column='item_id', on_delete=models.CASCADE, related_name='item_props')
Query should become:
ServiceItem.objects.filter(Q(item_type='CARD') & (Q(item_props__key='bouncebacks') | Q(item_props__key='assignees'))
==============================================================
I think I misunderstood your query.
I believe this is a good case to use .raw() .
Try this one instead:
qs = ServiceItemProps.objects.raw('''
SELECT sip1.*, sip2.value as other_value
FROM {item_table} as service_items
INNER JOIN {props_table} as sip1 on sip1.item_id = service_items.id
INNER JOIN {props_table} as sip2 on sip2.item_id = service_items.id
WHERE service_items.item_type='CARD' and sip1.key='bouncebacks' and sip2.key='assignees'
'''.format(item_table=ServiceItems._meta.db_table, props_table=ServiceItemProps._meta.db_table)
for itemprop in qs:
print(qs.value, qs.other_value)