postgres change jsonb[] to jsonb

Question

I use postgres9.4, and there exists relation \"Patients\" has column \"contact\" with type jsonb[], how to transfer type jsonb[] to

Answer 1

If only the first element of jsonb array is used then the issue is simple:

alter table "Patients" alter column contact type jsonb using contact[1]::jsonb;

else you can use the following function:

create or replace function jsonb_array_to_jsonb(jsonb[])
returns jsonb language sql as $$
    select jsonb_object_agg(key, value)
    from unnest($1), jsonb_each(unnest)
$$;

alter table "Patients" alter column contact type jsonb using jsonb_array_to_jsonb(contact);