Postgres/JSON - update all array elements

Question

Given the following json:

{
  \"foo\": [
    {
      \"bar\": true
    },
    {
      \"bar\": true
    }
  ]
}

How can I select the follow

Answer 1

There is no standard function to update json array elements by key. A custom function is probably the simplest way to solve the problem:

create or replace function update_array_elements(arr jsonb, key text, value jsonb)
returns jsonb language sql as $$
    select jsonb_agg(jsonb_build_object(k, case when k <> key then v else value end))
    from jsonb_array_elements(arr) e(e), 
    lateral jsonb_each(e) p(k, v)
$$;

select update_array_elements('[{"bar":true},{"bar":true}]'::jsonb, 'bar', 'false');

      update_array_elements
----------------------------------
 [{"bar": false}, {"bar": false}]
(1 row)

Your query may look like this:

with a_data(js) as (
values(
    '{
        "foo": [
          {
            "bar": true
          },
          {
            "bar": true
          }
        ]
    }'::jsonb)
)
select
    jsonb_set(js, '{foo}', update_array_elements(js->'foo', 'bar', 'false'))
    from a_data;

                 jsonb_set                 
-------------------------------------------
 {"foo": [{"bar": false}, {"bar": false}]}
(1 row)