postgresql – Postgres SQL: View with a nested table

I have 2 tables users & groups:

user_id | title         group_id | title  
----------------        ------------------
U_1     | User 1        G_1      | Group 1
U_2     | User 2        G_2      | Group 2
                        G_3      | Group 3

I have a mapping table between users and groups (a many to many relationship):

members

group_id | user_id | user_type
------------------------------
G_1      | U_1     | admin    
G_1      | U_2     | member   
G_2      | U_1     | admin    
G_3      | U_2     | admin    

I’m looking to create a materialized view with nested tables as follows

user_id | title  | groups            
----------------------------------------
U_1     | User 1 | group_id | user_type
        |        |----------------------
        |        | G_1      | admin    
        |        | G_2      | admin    
----------------------------------------
U_2     | User 2 | group_id | user_type
        |        |----------------------
        |        | G_1      | member   
        |        | G_3      | admin    

In my node.js app, I’m basically expecting the following

(
{
    "user_id": "U_1",
    "title": "User 1",
    "groups": ({"group_id": "G_1","user_type": "admin"},{"group_id": "G_2","user_type": "admin"})
},
{
    "user_id": "U_2",
    "title": "User 2",
    "groups": ({"group_id": "G_1","user_type": "member"},{"group_id": "G_3","user_type": "admin"})
},
)

This was easy to achieve using MySQL (cast multiset), but I’m having trouble with postgres… Plz help…