在Go中合并动态数据结构

Question

我有传入的有效负载，无法更改。

{
"source": "some random source",
"table": "hosts_table",
"data": [
    ["address", "id", "services_with_info"],
    ["0.0.0.1", 1111, [
            ["service_3", "is very cool", 1],
            ["service_4", "is very cool", 2]
        ]
    ],
    ["0.0.0.2", 2222, [
            ["service_3", "is very cool", 3],
            ["service_4", "is very cool", 4]
        ]
    ]
]}

我需要获取“数据”的第一个索引并创建一个新的JSON对象，如下所示…

"data": [{
"address": "0.0.0.1", 
"id": 1111, 
"services_with_info":[
    {
        "service_name": "service_1", 
        "service_message": "is very cool", 
        "service_id": 1
    }, 
    {...}
]}, 
{...}]

然后[]Host从中构建一个，其数据结构的长度为5k个“主机”。我能够将其映射到结构，但需要首先将其转换为这种格式。我了解如何解组JSON，但前提是可以将有效负载转换为上述格式。

Answer 1

我不确定我是否了解您的需求。

可能是这样的事情？可能需要做一些工作，例如使指向结构的指针切片而不是结构的切片以防止分配和复制，错误处理，更多自定义逻辑来转换值，匿名化/封装转换中间使用的私有结构，向其中添加json标签这些结构等

我在IncomingPaylod上为Data字段创建了自定义的Unmarshaller：解析期望的数据，将其转换为[]
MyData并使用它更新Data字段。

我为Expected_data和Expected_services_with_info创建了自定义Unmarshallers，因为我们希望它作为值数组（3个值：字符串，整数和[字符串数组，整数（？），整数]），但是我想将其转换为漂亮的结构。如果您不喜欢它，可以将其删除，将所需的数据解组到[]
interface {}，并像[] interface {} {string，int，[] interface {}
{string，int，int}}一样使用它。容易出错，因此我更喜欢结构，它更易于阅读，维护和重构（我认为您的应用程序中包含更多字段）。

https://play.golang.org/p/xHTvyhecra

package main

import (
    "encoding/json"
    "fmt"
    "strconv"
)

type IncomingPayload struct {
    Source string      `json:"source"`
    Table  string      `json:"table"`
    Data   MyDataSlice `json:"data"`
}
type MyDataSlice []MyData

type MyData struct {
    Address            string              `json:"address"`
    ID                 string              `json:"id"`
    Services_with_info []MyServiceWithInfo `json:"services_with_info"`
}

type MyServiceWithInfo struct {
    ServiceName    string `json:"service_name"`
    ServiceMessage string `json:"service_message"`
    ServiceID      int    `json:"service_id"`
}

type expected_data struct {
    IP   string
    ID   int
    Info []expected_services_with_info
}

type expected_services_with_info struct {
    Name string
    Desc string
    ID   int
}

func (ed *expected_data) UnmarshalJSON(buf []byte) error {
    tmp := []interface{}{&ed.IP, &ed.ID, &ed.Info}
    // converts ["address", "id", "services_with_info"] into a struct
    // will unmarshall "services_with_info" (ed.Info) with *expected_services_with_info.UnmarshalJSON
    json.Unmarshal(buf, &tmp)
    return nil
}

func (es *expected_services_with_info) UnmarshalJSON(buf []byte) error {
    tmp := []interface{}{&es.Name, &es.Desc, &es.ID}
    // converts ["service_3", "is very cool", 1] into a struct
    json.Unmarshal(buf, &tmp)
    return nil
}

func (md *MyDataSlice) UnmarshalJSON(p []byte) error {
    var incoming_data_slice []expected_data
    json.Unmarshal(p, &incoming_data_slice)
    //fmt.Println("incoming", incoming_data_slice)

    //transform incoming_data_slice to your needs using your data type
    for i := range incoming_data_slice {
        my_data := MyData{
            Address: incoming_data_slice[i].IP,               //copy
            ID:      strconv.Itoa(incoming_data_slice[i].ID), //some transformation
            //nil slice is totally fine, but if you wish you can do
            //Data: make(MyDataSlice, len(incoming_data_slice)),

        }

        //not sure what would be best: "i := range data" or "_, v := range data" (second one makes a copy? and causes allocation)
        for j := range incoming_data_slice[i].Info {
            tmp := MyServiceWithInfo{
                ServiceName: incoming_data_slice[i].Info[j].Name,
                ServiceMessage: incoming_data_slice[i].Info[j].Desc,
                ServiceID: incoming_data_slice[i].Info[j].ID,
            }
            my_data.Services_with_info = append(my_data.Services_with_info, tmp)
        }

        //and populate
        *md = append(*md, my_data)
    }

    return nil
}

func main() {

    test_json := `{
"source": "some random source",
"table": "hosts_table",
"data": [
    ["address", "id", "services_with_info"],
    ["0.0.0.1", 1111, [
            ["service_3", "is very cool", 1],
            ["service_4", "is very cool", 2]
        ]
    ],
    ["0.0.0.2", 2222, [
            ["service_3", "is very cool", 3],
            ["service_4", "is very cool", 4]
        ]
    ]
]}`

    var payload IncomingPayload
    json.Unmarshal([]byte(test_json), &payload)
    fmt.Println("payload", payload)

    buf, _ := json.MarshalIndent(payload, "", "\t")
    fmt.Println(string(buf))

}