Postgresql, how to SELECT json object without duplicated rows - postgresql

Question

I'm trying to find out how to get JSON object results of selected rows, and not to show duplicated rows.
My current query:
SELECT DISTINCT ON (vp.id) jsonb_agg(jsonb_build_object('affiliate',a.*)) as affiliates, jsonb_agg(jsonb_build_object('vendor',vp.*)) as vendors FROM
affiliates a
INNER JOIN related_affiliates ra ON a.id = ra.affiliate_id
INNER JOIN related_vendors rv ON ra.product_id = rv.product_id
INNER JOIN vendor_partners vp ON rv.vendor_partner_id = vp.id
WHERE ra.product_id = 79 AND a.is_active = true
GROUP BY vp.id
The results that I receive from this is:
[
affiliates: {
affiliate: affiliate1
affiliate: affiliate2
},
vendors: {
vendor: vendor1,
vendor: vendor1,
}
As you can see in the second record, vendor is still vendor1 because there are no more results, so I'd like to also know if there's a way to remove duplicates.
Thanks.

Answer 1

First point : the result you display here above doesn't conform the json type : the keys are not double-quoted, the string values are not double-quoted, having dupplicated keys in the same json object ('{"affiliate": "affiliate1", "affiliate": "affiliate2"}' :: json) is not be accepted with the jsonb type (but it is with the json type).
Second point : you can try to add the DISTINCT key word directly in the jsonb_agg function :
jsonb_agg(DISTINCT jsonb_build_object('vendor',vp.*))
and remove the DISTINCT ON (vp.id) clause.
You can also add an ORDER BY clause directly in any aggregate function. For more information, see the manual.

Answer 2

You could aggregate first, then join on the results of the aggregates:
SELECT a.affiliates, v.vendors
FROM (
select af.id, jsonb_agg(jsonb_build_object('affiliate',af.*)) as affiliates
from affiliates af
group by af.id
) a
JOIN related_affiliates ra ON a.id = ra.affiliate_id
JOIN related_vendors rv ON ra.product_id = rv.product_id
JOIN (
select vp.id, jsonb_agg(jsonb_build_object('vendor',vp.*)) as vendors
from vendor_partners vp
group by vp.id
) v ON rv.vendor_partner_id = v.id
WHERE ra.product_id = 79
AND a.is_active = true