json - 从golang中的嵌套动态键json获取数据

Question

我是新来的，我正在尝试从 json 结构中提取特定的 key ，如下所示。

{
    "cluster_name": "escluster",
    "nodes": {
        "Sd2AvEXsswjTn6ErRYjg": {
            "timestamp": 1460624696217,
            "name": "master1",
            "transport_address": "10.0.0.1:9300",
            "host": "10.0.0.1:9300",
            "ip": [
                "10.0.0.1:9300",
                "NONE"
            ],
            "attributes": {
                "data": "false",
                "master": "true"
            },
            "os": {
                "timestamp": 1460624696217,
                "cpu_percent": 0,
                "load_average": 0,
                "mem": {
                    "total_in_bytes": 163987664,
                    "free_in_bytes": 136357264,
                    "used_in_bytes": 26629400,
                    "free_percent": 84,
                    "used_percent": 16
                },
                "swap": {
                    "total_in_bytes": 0,
                    "free_in_bytes": 0,
                    "used_in_bytes": 0
                }
            }
        },
        "yzabB-OaTfOqvgAELIMq1Q": {
            "timestamp": 1460624938213,
            "name": "data_1",
            "transport_address": "10.0.0.2:9300",
            "host": "10.0.0.2",
            "ip": [
                "10.0.0.2:9300",
                "NONE"
            ],
            "attributes": {
                "master": "false"
            },
            "os": {
                "timestamp": 1460624938213,
                "cpu_percent": 0,
                "load_average": 0.29,
                "mem": {
                    "total_in_bytes": 623840000,
                    "free_in_bytes": 4127648,
                    "used_in_bytes": 666012352,
                    "free_percent": 1,
                    "used_percent": 99
                },
                "swap": {
                    "total_in_bytes": 0,
                    "free_in_bytes": 0,
                    "used_in_bytes": 0
                }
            }
        },
        "q5CdgUF2TRewujr-0RPMgQ": {
            "timestamp": 1460624934417,
            "name": "master_0",
            "transport_address": "10.0.0.3:9300",
            "host": "10.0.0.2",
            "ip": [
                "10.0.0.3:9300",
                "NONE"
            ],
            "attributes": {
                "data": "false",
                "master": "true"
            },
            "os": {
                "timestamp": 1460624934417,
                "cpu_percent": 0,
                "load_average": 0,
                "mem": {
                    "total_in_bytes": 163898764,
                    "free_in_bytes": 139705616,
                    "used_in_bytes": 24194588,
                    "free_percent": 85,
                    "used_percent": 15
                },
                "swap": {
                    "total_in_bytes": 0,
                    "free_in_bytes": 0,
                    "used_in_bytes": 0
                }
            }
        }
    }
}      

由于节点名称是动态的，我想为每个节点检索 mem。我找到了 this检索数据但不是动态 key 。我们如何在 go 中执行此操作。

Answer 1

学习如何在 Go 中处理数据的一个很好的引用:http://blog.golang.org/json-and-go

关于你的问题，在我看来你的数据结构相对良好......我在以下 Playground 示例中设置了一个提取每个节点的 mem 部分的示例:

http://play.golang.org/p/0O5U-3N_tA

它的要点是任何强指定都可以编码为struct。什么是动态的(例如你的节点名称)可以被编码为 map 。两者可以任意混合，因此:

type Node struct {
    Timestamp        uint64            `json:timestamp`
    Name             string            `json:name`
    TransportAddress string            `json:transport_address`
    Host             string            `json:host`
    Ip               []string          `json:ip`
    Attributes       map[string]string `json:attributes`
    Os               *OsInfo           `json:os`
}

type Payload struct {
    Name  string           `json:cluster_name`
    Nodes map[string]*Node `json:nodes`
}

可以捕获节点的一般结构(通过其 struct 定义)和它们被动态索引的事实(通过节点本身存储在动态 map 中的事实) 。

一旦解码，处理数据以提取内存信息就变得微不足道了:它只是众所周知的结构并一直向下映射:

var p Payload
if err := json.Unmarshal([]byte(payload), &p); err != nil {
    log.Fatal(err)
}
for k, node := range p.Nodes {
    fmt.Printf("%s: %s\n", k, node.Os.Mem)
}

预期的输出:

Sd2AvEXsswjTn6ErRYjg: map[total_in_bytes:%!s(uint64=163987664) free_in_bytes:%!s(uint64=136357264) used_in_bytes:%!s(uint64=26629400) free_percent:%!s(uint64=84) used_percent:%!s(uint64=16)]
yzabB-OaTfOqvgAELIMq1Q: map[used_percent:%!s(uint64=99) total_in_bytes:%!s(uint64=623840000) free_in_bytes:%!s(uint64=4127648) used_in_bytes:%!s(uint64=666012352) free_percent:%!s(uint64=1)]
q5CdgUF2TRewujr-0RPMgQ: map[total_in_bytes:%!s(uint64=163898764) free_in_bytes:%!s(uint64=139705616) used_in_bytes:%!s(uint64=24194588) free_percent:%!s(uint64=85) used_percent:%!s(uint64=15)]

(您当然可以先提取/重新格式化您的数据，并在完成后立即丢弃 Payload 对象)