Add new array element to JSON object in Node-Postgres - node.js

Question

I have a json field in a postgres database that looks something like this :
{
"first_name": "John",
"last_name": "Doe",
"email": "johndoe#example.org",
"reviews" :[
{
"comment": "John gave us great service! Love this guy!",
"last_name": "Mariana",
"first_name": "Brown"
}
]
}
Using node, I'm trying to add a new array element (a new review) to the reviews. I want to be able to do this dynamically. The query I'm using ads in a array at index 2. That is not dynamic. I did find helpful material here but all the answers don't tell you how to update(add) to second level keys like the one in my situation. How can I do this?
Query
var text ="UPDATE users SET info = JSONB_SET(info, '{reviews,2}', '"+review+"') WHERE id=$1 RETURNING*";//works but not dynamic
var values = [userid];
pool.query(text, values, (err, res) => {
if (err) {
//log errors
console.log(err.stack);
//return error
io.to(socketid).emit('review-sent',{valid:'false'});
} else {
//success
console.log(res.rows );
var json = res.rows;
//success
io.to(socketid).emit('review-sent',{valid:'true'});
}
});

Answer 1

You can use jsonb_insert() if that is given a negative index it counts from the end. Passing true as the third parameter will then insert the new value after that, so jsonb_insert(..., '{reviews, -1}', true) will append the new value at the end:
update users
set info = jsonb_insert(info,
'{reviews,-1}',
'{"comment": "...", "last_name": "...", "first_name": "..."}',
true)
where id = 1;