On Sep 10, Tim Uckun modulated:
> I am trying to get the child elements of a one to many table to be
> rolled up into a json field in the parent table. The query I am running
> is...
The problem is aggregating over the results of the left-outer join,
which introduces NULLs. You can try pushing that down into a sub-query
to create one image row per observation prior to joining:
SELECT
ob.id,
im.images
FROM observations ob
LEFT OUTER JOIN (
SELECT
observation_id,
json_agg(row_to_json(im.*)) AS images
FROM images im
GROUP BY observation_id
) im ON (ob.id = im.observation_id) ;
you might use COALESCE in the top-level SELECT if you want to replace
any NULL im.images with a different empty value constant...
Karl
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