Is PostgreSQL array_to_json is a bad practice? - sql

Question

I have a habit of writing queries that returns JSON structures directly from the PostgreSQL query,
-- Something like this...
-- The function
CREATE OR REPLACE FUNCTION get_data(_team_id UUID) RETURNS JSON AS
$$
DECLARE
_output JSON;
BEGIN
SELECT ROW_TO_JSON(rec)
INTO _output
FROM (SELECT COUNT(*) AS total
FROM users,
(SELECT ARRAY_TO_JSON(ARRAY_AGG(ROW_TO_JSON(a))) AS data
FROM (SELECT id,
name,
(SELECT ARRAY_TO_JSON(ARRAY_AGG(ROW_TO_JSON(b))) AS emails
FROM (SELECT email
FROM emails
WHERE user_id = users.id) b)
FROM users
WHERE active IS TRUE
AND team_id = _team_id
ORDER BY name
LIMIT 5 OFFSET 0) a)
WHERE active IS TRUE
AND team_id = _team_id) rec;
RETURN _output;
END;
$$ LANGUAGE plpgsql;
-- The query
SELECT get_data('ee0a7ea0-3888-476b-810e-de93a58aa6f6') AS data;
This gives me the below structure for my JavaScript web application,
{
"total": 100,
"data": [
{ "id": 1, "name": "User 1", "emails": [{"email": "email1"}, {"email": "email2"}] },
{ "id": 2, "name": "User 2", "emails": [{"email": "email1"}, {"email": "email2"}] },
{ "id": 3, "name": "User 3", "emails": [{"email": "email1"}, {"email": "email2"}] },
{ "id": 4, "name": "User 4", "emails": [{"email": "email1"}, {"email": "email2"}] },
{ "id": 5, "name": "User 5", "emails": [{"email": "email1"}, {"email": "email2"}] }
]
}
Since I'm new to querying, I see that building the structure directly from the query saves a lot of time over building the view models from JavaScript.
But I have some hesitations. Is this the best way to approach it? Or not?
I searched through the internet and find nothing about this.

Answer 1

The best approach is to generate the SQL queries not by hand but let an ORM like TypeORM (Typescript) or JPA (Java, implemented by Hibernate and Eclipselink) or Eloquent (PHP) do this for you.
With TypeORM and a matching entity model, your code would be:
const users = await entityManager.getRepository(User)
.createQueryBuilder('user')
.where('user.active = true')
.andWhere('user.team_id = :teamId', {teamId: 1})
.getManyAndCount();
This is much cleaner than the SQL query you have written and it allows for code reuse.
That way, if you e.g. change the type of a column or if you want a custom mapping (Postgres dates, ...) or whatever, you can use the ORM for that and don't have to copy+paste the code into every query.