How to join one to many relationship using db.select api and get nested array in result

[shellking4]

So let's suppose I have tables users and posts where a user owns many posts
How to retrieve a user with his posts using db.select and get back a result like
[
{ userId: "sjvhbdsh", posts: [ {"postId": "sdbdjvbsjbv"} ] }
]
And this without any js transformatio, just with specifying fields in the select method

[sbscan]

I could not succeed and plan to change from mariadb to mysql just to be able to user query syntax to get this nested object. It's very convenient for JS devs.