Postgres: create a new jsonb object with matched values - postgresql

Question

So I have this table questions that have a settings jsonb column:
{
id: 'question-id-1',
settings: {
foo1: true,
foo2: true,
bar: false
}
},
{
id: 'question-id-2',
settings: {
bar: true
}
}
now I want to make a postgres db update migration script that results to:
{
id: 'question-id-1',
settings: {
foo1: true,
foo2: true,
bar: false,
opts: ['foo1', 'foo2']
}
},
{
id: 'question-id-2',
settings: {
bar: true,
opts: ['bar']
}
}
so only those that has values true is added to a new opts array inside settings.
This is for Postgres 9.5.
Thank you in advanced.

Answer 1

Create a function to update the column:
create or replace function add_opts(jsonb)
returns jsonb language sql as $$
select $1 || jsonb_build_object('opts', jsonb_agg(key))
from jsonb_each_text($1)
where value::bool;
$$;
Test:
with questions(settings) as (
values
('{
"foo1": true,
"foo2": true,
"bar": false
}'::jsonb)
)
select add_opts(settings)
from questions;
add_opts
----------------------------------------------------------------------
{"bar": false, "foo1": true, "foo2": true, "opts": ["foo1", "foo2"]}
(1 row)
Your update query should look like this:
update questions
set settings = add_opts(settings);
The variant which eliminates the opts array when there are no set options:
create or replace function add_opts(jsonb)
returns jsonb language sql as $$
select case
when jsonb_agg(key) is null then $1
else $1 || jsonb_build_object('opts', jsonb_agg(key))
end
from jsonb_each_text($1)
where value::bool;
$$;