Filtering JSONB data in Postgres

filter-data.sql

-- Postgres: How to find a matching element in a JSON array
-- 
-- Definitions:
-- - animal_size_in_mm: int = 50
-- - var_animal_type: string = "fish"
-- 
-- Data example:
-- 
-- [
--   { "animal_type": "fish", "name": "Bob", "animal_size": 48 },
--   { "animal_type": "fish", "name": "Simon", "animal_size": 54 },
--   { "animal_type": "spider", "name": "Mark", "animal_size": 28 },
--   { "animal_type": "spider", "name": "Chonk", "animal_size": 62 },
-- ]
-- 

(jsonb_path_query_first(
  some_query_alias.some_jsonb_field,
  '$[*] ? (@.animal_type == $animal_type_var)',
  jsonb_build_object(
    'animal_type_var', var_animal_type
  )
)->>'animal_size')::int <= animal_size_in_mm::int

-- 
-- Will return the following results:
-- { "animal_type": "fish", "name": "Bob", "animal_size": 48 }
-- { "animal_type": "spider", "name": "Mark", "animal_size": 28 }
-- 
-- This is because both these entries have an animal_size <= 50