从 mongodb 的 2 个集合中的 find 生成一个 json

Question

你能帮我从两个集合中生成一个 json：

用户 [user_id, user_name, city_id]

[
    {
        "name": "Anton",
        "user_id": 1,
        "city_id": 1
    },
    {
        "name": "Vasiliy",
        "user_id": 2,
        "city_id": 2
    }
]

城市 [ city_id, city_name ]

[
    {
        "name": "Kharkov",
        "city_id": 1
    },
    {
        "name": "Kiev",
        "city_id": 2
    }
]

JSON 像这样：

[
        {
            "user_name": "Anton",
            "city_name": "Kharkov",
            "user_id": 1,
        },
        {
            "user_name": "Vasiliy",
            "city_name": "Kiev",
            "user_id": 2,
        }
]

Answer 1

您需要在应用层中进行连接，无法在 MongoDB 中连接数据。每当您在两个集合中有数据时，您都必须发出两个查询。