我有如下表结构的postgresql：

CREATE TABLE "objs"("number" Integer,"name" Text NOT NULL,  "price" Text NOT NULL );
CREATE TABLE "users"("name" Text NOT NULL,"obj_number" Text NOT NULL );

INSERT INTO "objs" ("number","name","price") VALUES ( 1,'Small Red Apples','30' );
INSERT INTO "objs" ("number","name","price") VALUES ( 1,'Big Apples','50' );
INSERT INTO "objs" ("number","name","price") VALUES ( 2,'Small Bottle','24' );
INSERT INTO "objs" ("number","name","price") VALUES ( 2,'Big Bottle','60' );
INSERT INTO "objs" ("number","name","price") VALUES ( 1,'Small green Apples','45' );

INSERT INTO "users" ("name","obj_number") VALUES ( 'Mike','1' );
INSERT INTO "users" ("name","obj_number") VALUES ( 'Jow','2' );
INSERT INTO "users" ("name","obj_number") VALUES ( 'Piter','3' );

我需要以json格式返回select结果：

[
{
        "id": "1",
        "name": "Mike",
        "objs": 
        [
            {
                "number": 1,
                "name": "Small Red Apples",
                "price": "30"
            },
            {
                "number": 1,
                "name": "Small green Apples",
                "price": "45"
            },
            {
                "number": 1,
                "name": "Big Apples",
                "price": "50"
            }
        ]
    },
    {
        "id": 2,
        "name": "Jow",
        "objs": [{
                "number": 1,
                "name": "Small Bottle",
                "price": "50"
            },
            {
                "number": 1,
                "name": "Small Bottle",
                "price": "24"
            }
        ]
    },
    {
        "id": 2,
        "name": "Jow",
        "objs": []
    }
]

似乎我需要混合左加入和分组，但我不知道怎么做：

SELECT
    u."name",
    u."obj_number",
    o."name",
    o."price"
FROM "users" u 

LEFT JOIN objs o ON u.obj_number = o."number" 

-- GROUP BY u."name"