查询MongoDB文档中的特定对象并仅检索该对象

Question

如何查询MongoDB文档中的特定对象并仅检索该对象

文献：

{
    "_id" : "mac_table",
    "00:50:56:84:c8:1b" : {
        "switch_port" : "ethernet1/37",
        "mac_ip_routed_by" : "or1-befw02",
        "mac_switch" : "adsfasfd",
        "mac_ip" : "ddsfa",
        "switch_port_description" : "asdfsafsfda",
        "mac_ip_dns" : "asdfsafd",
        "switch_port_mode" : "trunk",
        "mac_vlan:" : "3362"
    },
    "00:50:56:84:c8:1f" : {
        "switch_port" : "ethernet1/13",
        "mac_ip_routed_by" : "asdf",
        "mac_switch" : "dfdsfd",
        "mac_ip" : "asdfasdf",
        "switch_port_description" : "adsfasdf",
        "mac_ip_dns" : "asdfasfd",
        "switch_port_mode" : "trunk",
        "mac_vlan:" : "3201"
    },
    "00:50:56:a5:64:f0" : {
        "switch_port" : "",
        "mac_ip_routed_by" : "adsfdfsa",
        "mac_switch" : "",
        "mac_vlan" : "",
        "mac_ip" : "adsfasdf",
        "switch_port_description" : "",
        "mac_ip_dns" : "adadfsadf",
        "switch_port_mode" : "asdsadf"
    },
    "18:a9:05:65:43:12" : {
        "switch_port" : "ethernet116/1/6",
        "mac_ip_routed_by" : "nvvvvvv",
        "mac_switch" : "aaana",
        "mac_ip" : "10.40.77.60",
        "switch_port_description" : "test",
        "mac_ip_dns" : "test",
        "switch_port_mode" : "access",
        "mac_vlan:" : "76"
    }
}

我只想检索：

"00:50:56:84:c8:1b" : {
        "switch_port" : "ethernet1/37",
        "mac_ip_routed_by" : "or1-befw02",
        "mac_switch" : "adsfasfd",
        "mac_ip" : "ddsfa",
        "switch_port_description" : "asdfsafsfda",
        "mac_ip_dns" : "asdfsafd",
        "switch_port_mode" : "trunk",
        "mac_vlan:" : "3362"
    }

对于我尝试的每个查询，它返回整个文档，我在这个单个文档中有大约30K个对象。如果我错误地构造数据，请告知如何更好地构建数据以获得我需要的查询。我担心添加30K文档和1个带有30k对象的文档。

Answer 1

你应该能够像这样简单地使用projection：

db.collection.find({}, { "00:50:56:84:c8:1b": 1 })