How to get an associative array of rows from a subquery with postgres - postgresql

Question

I'm new to postgres and trying out some things before I take the leap over from mySQL.
What I'm trying to do is get an array of associative arrays into a single query.
It has to do with users that can select multiple contact types like phone, email and Facebook and I would like to retrieve those into the column 'contact'.
For a visualisation:
{
"first_name": "This",
"last_name": "is me",
"likes": [],
"city": null
}
And I would like to get something like this:
{
"first_name": "This",
"last_name": "Is me",
"likes": [],
"city": null,
"contact":
[
{"type":1, "value":"myemail#gmail.com", "privacy_rule":1},
{"type":4, "value":"myfacebook", "privacy_rule":1},
{"type":9, "value":"mylinkedin", "privacy_rule":1}
]
}
So the main query would be:
SELECT u.first_name, u.last_name, u.about, ARRAY(SELECT like_id FROM users_likes l WHERE l.user_id = u.user_id), u.city FROM users u WHERE user_id = {id}
The subquery would be:
SELECT c.type, c.value, c.privacy_rule FROM users_contact c WHERE c.user_id = u.user_id
But how do I integrate it in the main query to return the array of result rows?
Is it even possible?
Thanks in advance!
Ron

Answer 1

Ah, after some more filling about, here is the answer.
use json_build_object:
SELECT u.first_name, u.last_name,
ARRAY(SELECT like_id FROM users_likes l WHERE l.user_id = u.user_id) as likes,
ARRAY(SELECT json_build_object("contact_id", c.contact_id,
"value", c.value, "privacy",c.privacy)
FROM users_contact c WHERE c.user_id = u.user_id) as contact
FROM users_basic u WHERE user_id = {id}
This gives:
"first_name": "This",
"last_name": "Is Me",
"about": null,
"likes": [],
"city": null,
"contact": [
{
"contact_id": 1,
"value": "bbla",
"privacy": 2,
"type": "Phone"
},
{
"contact_id": 3,
"value": "blabla",
"privacy": 2,
"type": "Company Email"
},
{
"contact_id": 4,
"value": "blablabla",
"privacy": 2,
"type": "Telegram Id"
}
]
Hope it helps someone