Concatenate multiple json objects into json array - json

Question

I'm trying to build JSON objects in a loop and store those objects in a JSON array.
I tried to use array_append, json_agg, json_object_agg, but I couldn't get the expected result. Please find the code snippets below.
RETURNS json
as
$$
DECLARE
x text;
obj json;
result json;
y text;
nums json;
BEGIN
FOREACH x IN ARRAY arr
loop
-- doing some id conversion for x
obj = json_build_object('id',x);
result = json_build_array(obj,result);
END LOOP;
return result;
end;
$$
LANGUAGE plpgsql;
The expected output here is :
[
{"id" : "596339663235613739646562"},
{"id" : "506130306666363361633763"},
{"id" : "526362363532646435613438"},
{"id" : "543639333134353433393631"}]
But the actual output I get :
[[[[null, {"id" : "596339663235613739646562"}],
{"id" : "506130306666363361633763"}],
{"id" : "526362363532646435613438"}],
{"id" : "543639333134353433393631"}]
A sample input for function is :
{596339663235613739646562,506130306666363361633763,526362363532646435613438,543639333134353433393631}
Any help is greatly appreciated. Thanks.

Answer 1

Try this :
SELECT jsonb_agg(jsonb_build_object('id', a :: text))
FROM unnest('{596339663235613739646562,506130306666363361633763,526362363532646435613438,543639333134353433393631}' :: text[]) AS a
and an attemp to implement your function favoritesArray in sql (but with no guarantee, you have to adapt this suggestion to your exact need, or provide more info about your database schema and the expected result of your function) :
CREATE OR REPLACE FUNCTION favoritesArray(arr text[])
RETURNS json LANGUAGE sql as $$
SELECT json_agg(json_build_object('id', lpad(x , 32, '0') :: text, 'logicalPath', t1.name || t2.path))
FROM unnest(arr) AS x
INNER JOIN schema.table2 AS t2
ON t2.key = x
INNER JOIN schema.table1 AS t1
ON t1.key = t2.source ;
$$ ;
see dbfiddle