PostgreSQL transform value from jsonb column to other column - postgresql

Question

I have a PostgreSQL database v10 with the following data:
CREATE TABLE test (
id INT,
custom_fields jsonb not null default '{}'::jsonb,
guest_profile_id character varying(100)
);
INSERT INTO test (id, custom_fields) VALUES (1, '[{"protelSurname": "Smith", "servicio_tags": ["protel-info"], "protelUniqueID": "[{\"ID\":\"Test1-ID\",\"Type\":\"21\",\"ID_Context\":\"GHA\"}{\"ID\":\"4842148\",\"Type\":\"1\",\"ID_Context\":\"protelIO\"}]", "protelGivenName": "Seth"}, {"value": "Test", "display_name": "Traces", "servicio_tags": ["trace"]}, {...}]');
INSERT INTO test (id, custom_fields) VALUES (2, '[{"protelSurname": "Smith", "servicio_tags": ["protel-info"], "protelUniqueID": "[{\"ID\":\"Test2-ID\",\"Type\":\"21\",\"ID_Context\":\"GHA\"},{\"ID\":\"4842148\",\"Type\":\"1\",\"ID_Context\":\"protelIO\"}]", "protelGivenName": "Seth"}, {"value": "Test2", "display_name": "Traces", "servicio_tags": ["trace"]}, {...}]');
INSERT INTO test (id, custom_fields) VALUES (3, '[{"value": "Test3-ID", "display_name": "Test", "servicio_tags": ["person-name"]}, {...}]');
INSERT INTO test (id, custom_fields) VALUES (4, '[{"value": "Test4-ID", "display_name": "Test", "servicio_tags": ["profile-id"]}, {...}]');
There are way more records in the real table.
Goal: I want to transfer the TestX-ID values into the column guest_profile_id in the same row. And only those values not the other JSONB objects or values etc.
My try:
do $$
declare
colvar varchar;
begin
select x ->> 'ID' from (select jsonb_array_elements(f) from (
select (field ->>'protelUniqueID')::jsonb f
FROM guest_group gg,
lateral jsonb_array_elements(custom_fields) AS field
WHERE value #> '{"servicio_tags": ["protel-info"]}'::jsonb
) d(f)) dd(x)
where x->>'ID_Context'='protelIO'
into colvar;
raise notice 'colvar: %', colvar;
end
$$;
execute format('UPDATE guest_group SET guest_profile_id = %s, colvar);
My Result: It only takes Test1-ID and stores it in all rows in the guest_profile_id column.
My Problem: I want to store each TestX-ID in the custom_fields column into the guest_profile_id column in the same row.
My assumption: I need to add a loop to this query. If the query up there does not find any value, the loop should try the next query: e.g.:
SELECT field ->>'value'
FROM guest_group gg
cross join lateral jsonb_array_elements(custom_fields) AS field
WHERE value #> '{"servicio_tags": ["profile-id"]}'::jsonb
And then the next:
SELECT field ->>'value'
FROM guest_group gg
cross join lateral jsonb_array_elements(custom_fields) AS field
WHERE value #> '{"servicio_tags": ["person-name"]}'::jsonb
When all TestX-ID values are copied into the guest_profile_id column in the same row, the goal is reached.
How can I put all this together? Thanks a lot for the help.

Answer 1

I want to store each TestX-ID in the custom_fields column into the guest_profile_id column in the same row.
No need for PL/PGSQL, loops or dynamic sql. Just use a single query of the form
UPDATE guest_group
SET guest_profile_id = (/* complex expression */);
In your case, with that complex expression it amounts to
UPDATE guest_group
SET guest_profile_id = (
SELECT x ->> 'ID'
FROM jsonb_array_elements(custom_fields) AS field,
jsonb_array_elements(field ->> 'protelUniqueID') AS dd(x)
WHERE value #> '{"servicio_tags": ["protel-info"]}'::jsonb
AND x->>'ID_Context' = 'protelIO'
);
If the query up there does not find any value, it should try the next query
You can use the COALESCE function for that, or add some OR conditions to your query, or even use a UNION. Alternatively, add a WHERE guest_profile_id IS NULL to the update statement to exclude those rows that already have a value, and do multiple successive updates.