Selecting for a Jsonb array contains regex match - regex

Question

Given a data structure as follows:
{"single":"someText", "many":["text1", text2"]}
I can query a regex on single with
WHERE JsonBColumn ->> 'single' ~ '^some.*'
And I can query a contains match on the Array with
WHERE JsonBColumn -> 'many' ? 'text2'
What I would like to do is to do a contains match with a regex on the JArray
WHERE JsonBColumn -> 'many' {Something} '.*2$'

Answer 1

I found that it is also possible to convert the entire JSONB array to a plain text string and simply perform the regular expression on that. A side effect though is that a search on something like
xt 1", "text
would end up matching.
This approach isn't as clean since it doesn't search each element individually but it gets the job done with a visually simpler statement.
WHERE JsonBColumn ->>'many' ~ 'text2'

Answer 2

Use jsonb_array_elements_text() in lateral join.
with the_data(id, jsonbcolumn) as (
values
(1, '{"single":"someText", "many": ["text1", "text2"]}'::jsonb)
)
select distinct on (id) d.*
from
the_data d,
jsonb_array_elements_text(jsonbcolumn->'many') many(elem)
where elem ~ '^text.*';
id | jsonbcolumn
----+----------------------------------------------------
1 | {"many": ["text1", "text2"], "single": "someText"}
(1 row)
See also this answer.
If the feature is used frequently, you may want to write your own function:
create or replace function jsonb_array_regex_like(json_array jsonb, pattern text)
returns boolean language sql as $$
select bool_or(elem ~ pattern)
from jsonb_array_elements_text(json_array) arr(elem)
$$;
The function definitely simplifies the code:
with the_data(id, jsonbcolumn) as (
values
(1, '{"single":"someText", "many": ["text1", "text2"]}'::jsonb)
)
select *
from the_data
where jsonb_array_regex_like(jsonbcolumn->'many', '^text.*');